Surgery GIT Flashcards

Question

Discuss the advantages and disadvantages of different imaging modalities for veiwing abnormalities of the ureters ?

Answer 1

Imaging modalities of the ureters (normal ureter diameter 1.3-2.7mm dog but dilates 17x with diuresis.) Ultrasound (the most sensitive modality) - sensitivity 100% dogs, 77% cats - can detect all stone types and soft tissue damage - identify hydroureters - hydronephrosis, may take days to develop (>10mm likely complete obstruction). Radiography - only detects radio opaque stones (but covers most stones) - lateral x2 and ventrodorsal - stone size, number, and location Fluroscope imaging - good quality modality to detect urethral obstructions or uretal rupture - antegrade pyelography (Invasive) - retrograde pyelography Imaging CT - IV contrast - associated risk of nephron damage - can differentiate partial / or complete obstruction

Answer 2

Obstructed ureter Medical treatment obstructed ureter - Mannitol - attempt diurese (increase urine volume) in an attempt to flush the ureters 1-4 days prior to commiting to surgery - induce relaxation of uretal smooth muscle (dilation) Indications for surgery to correct an obstructed ureter (remember your goal is to maintain kidney function) - unsuccessful medical treatment - pain in patient + inability to urinate - the benifits of avoiding surgery must be weighed against the risk of increasing renal damage secondary to obstruction.

Answer 3

Uretal obstruction Presentation and clinical signs - usually a young animal - asymetric kidney on palpation - renal pain - haematuria - crystalluria - urine is positive on culture Diagnosis - A ureteral obstruction must be identified on ultrasound, retrograde pyelograph or CT Treatment - ureterotomy - uteretal stent - subcutaneous urethral bypass (SUBS) - extracorporal shockwave therapy.

Answer 4

Treatment options for an obstructed ureter The length of the obstruction is usually unknown - therefore prognosis is difficult to predict - most cats have a degree of nephritis post treatment. - if azotaemic cat bilateral renal disease and MR 20% Medical = mannitol Surgery Old techniques Ureterotomy - removal of obstruction (dilation occurs proximal to the site of the obstruction) - nephrostomy - renal transplantation - uretal resection New techniques - Uretal stent - Subs (subcutaneous urethral bypass) + easier sampling via the bypass - extracorporeal shockwave lithrotripsy

Answer 5

Surgical correction uretal obstruction Old techniques - ureterostomy - uretal transection + anastomosis - nepthrostomy - neoureterocystostomy - ureteronephrectomy New techniques - uretal stent - SUBS subcutaneous urethral stent - shockwave lithrotripsy (nephroliths <10mm, ureteroliths <5mm) The advantage of the newer surgical techniques is the overcome the complication of post operative urethral stricture.

Answer 6

Ectopic ureter This is a congenital abnormality, caused by abnormal differentiation of the mesonephric duct - often in conjunction with other congenital abnormalities Intramural dogs - within bladder but directed ventrally Extramural cats - completely bypasses the bladder to the urethra, vagina - distal termination of the ureter is located distal to the end of the bladder Ectopic ureters clinical signs - Most common young female dogs - - predisposed breeds lab, goldie - uncommon in cats - continuous or intermittent incontinence - young fails to house train - urine scalding - normal voiding patterns - partial response to USMI medication - frequent licking of vulva

Answer 7

Diagnoses ectopic ureters (Observation of a ureter that travels distal to the trigone region of the bladder is considered diagnostic of an ectopic ureter). CBC, biochemistry - should be normal (unless infection present). Gold standard Cystoscopy + IVP - not possible in cats - ureters located in the same track as their biological origin Intravenous pyelogram IVP - series of X rays of kidney, ureter and bladder - injection contrast - can be difficult to detect intramural ureter - loss of J shape = straight ureter - help determine concurrent renal abnormalities - 76% accurate for ectopic ureters, and only 66% accurate for determining the location of the opening. Ultrasound - loss of jet flow from ureters at the trigone - ultrasound and radiograpghs equally sensitive for ectopic ureters

Answer 8

Ectopic ureters treatment options 1. Medical management often used in conjunction with surgery - Alpha adrenergic agonist = Phenylpropanolamine - usually trial medical management, and reccomend surgery is unsuccessful. 2. Surgery - Neoureterocystostomy - reimplant the ureter into the bladder

Answer 9

Classification of ectopic ureters (Based on their migration pathway) Extramural - ureter runs outside the bladder and opens directly into the vesicourethral junction, urethra, vagina or vestibule. - bypass the trigone completely Intramural ectopic ureter - ureter runs into the erosal surface of the bladder at a normal position, but fails to terminate and opens into the bladder at the tip of the trigone - disruption of the smooth muscle at the proximal urethral sphincter mechanism submucosal ureteral tunnel.

Answer 10

Ectopic ureters Signalment - most common young female dogs - less common in cats - predominate in labs and goldies Clinical signs - young pup which fails to house train - continuous or intermittent incontinence - incontenance is often worse in recumbancy - urine scolding - usually have a normal voiding pattern - frequent licking of vulva or preputial area (vulvovaginitis) - partial response to USMI medication.

Answer 11

Anatomy ureters Blood supply - cranially renal artery - caudally prostatic / vaginal artery Nerve supply - celiac and pelvic flexures Normal ureter diameter canine 1.3-2.7mm feline 1mm dilates upto 17x with diuresis

Answer 12

Pathogenesis of hip dysplasia Multifactorial aetiology - Genetic factors - Dietary factors - Conformational factors - Hip laxity Three mechanisms which lead to laxity, which then lead to remodelling of the joint and stretching of the ligament. 1. Lack of muscle to dynamically constrain passive constraints 2. Late ossification of bones means they are softer 3. Increased weight contributes to increased rim force 4. This is followed by micro-fracturing 5. Acetabular femoral remodelling 6. Stretching of the capsule and ligament 7. Increasing joint fluid

Answer 13

Hip dysplasia There are two clinical presentations - 6-9 months associated with hip laxity / synovitis - Mature dog associated with osteoarthritis Presenting signs - Gait abnormality / lameness - Difficulty rising - Reluctance to exercise - Crying in pain - Inability to jump Diagnoses Thorough history recording and general physical exam - Lameness examination - with patient standing assess muscle atrophy, stance - In lateral recumbency palpate for range of movement and pain - Palpation for hip joint laxity - Radiographic evaluation Ortolani sign - Assessment of hip laxity and angle of the acetabulum (open vrs closed) - Can be performed in dorsal and lateral recumbency - Requires deep sedation - Angle of reduction - Angle of subluxation - Thumb greater trochanter, rotate the stifle upwards until a clunk is felt (Ortonloni +ve) - Characteristics of “clunk” help assess damage to the acetabular rim (soft, hard, small vrs big clunk) Hip lift / Bardens test - positive result is trochanter can be elevated more than 6mm. Radiograpghs Standard extended VD view Much critism - Non-functional position - May artificially reduce hip laxity (screw in effect) - Lack of progress and early detection for breeding programs PennHIP (extended, compression and distraction) - Stress radiographic diagnostic method - Database / registry - International network of hip evaluation centres - Assessment on three different vies, extended compression and distraction - PennHIP at 4 months allows for early diagnosis and the ability to select within breeding programs - Does not mandate surgical treatment in absence of clinical signs

Answer 14

Surgical intervention must be weighed against relatively favourable results of conservative management. Conservative management / young dogs - Triple pelvic osteotomy (TPO) - Juvenile symphysiodesis (JPS) - Femoral head excision (FHO) Mature dogs - Conservative management - Total hip replacement (THR) - Femoral head ostectomy (FHO) - Capsular denervation

Answer 15

Conservative management The aim is to improve blood flow, relax muscles, improve mobility and relieve pain - Strict confinement and controlled exercise - Specific exercises / heat / massage / stretching - Dietary management / weight loss - Pain management /NSAIDS Metacam - NSAID side effects gastro irritation, impairment of renal function and platelet dysfunction. - Physical therapy - Ultra glucosamine / nutraceuticals

Answer 16

Triple / double pelvic osteotomy (TPO) Aim to rotate the acetabular segment of the pelvis to provide better femoral head coverage - Young dogs - Select animals with significant CS and no radiographic signs of hip OA - Significant hip laxity on palpation

Answer 17

Juvenile pubic symphysiodesis (JPS) - Requires early detection - Young dogs (3-5) months before disease has present clinically - Prophylactic surgery

Answer 18

Femoral head Ostectomy - Early surgery before severe atrophy - Craniolateral approach - Remove neck including the caudal shelf - Palpate excision site thoroughly Hip dysplasia / Total hip replacement - Specialist area - Definitive treatment for mature dog with sever pain due to OA - Provides excellent functional results - Surgical complications significant - Cemented and uncemented techniques - Unresponsive to medical treatment and unable to perform normal function in a mature dog - No other orthopaedic / neurological disease

Answer 19

Femoral head necrosis Pathology - Legg Calve Perthes disease - Trauma Aetiology - Mostly toy breeds (terriers_ - Genetic - Transient loss of blood supply - Femoral head becomes necrotic - As removal of dead bone occurs femoral head may collapse Clinical signs - Most cases present after femoral head collapse - Significant pain Diagnoses - Frog leg view for comparing affected and unaffected side - Bone lysis loss of definition Treatment Excision arthroplasty - Restores pain free function - THR is an alternative

Answer 20

Grading of patellar luxation Grades 1 to 4 – mild to most severe ( Grading one to four depending on the tendency of patella to luxate and ease of manual reduction). - The higher the grade number, the more severe the bony changes - Accurate assessment is critical to choosing the correct surgical treatment. Grade one - A knee-cap that can be luxated with manual pressure, but returns to the groove on its own. - Dose not require specific treatment but should be monitored Grade two - The knne cap dislocates spontaneously when the joint is flexed or extended, but returns to the groove when the joint is extended and lateral pressure is applied. - Often associated with a skipping lameness Grade three - The kneecap is permanently dislocated but can be manually returned to the groove. - Often associated with consistent lameness and limb deformities Grade four - The kneecap is permanently dislocated and can not be manually returned to the groove - Usually associated with severe lameness and limb deformities.

Answer 21

Abdominal hernia Any full thickness defect or weakness in the abdominal wall that may allow protrusion of abdominal contents. True defect - congenital weakness in the abdominal wall - mesothelium membrane (peritoneum) covering the contents. False defect - caused by blunt trauma - no sac (peritoneum) is present covering the hernia - this causes an increased risk of adhesions - can develop peritonealization over time. Acquired defect - iatrogenic (caused via incorrect surgery) - traumatic hernia - no peritonium sac so increased risk of adhesions Note; problematic hernias are usually just large enough to entrap viscera - very large hernias do not usually cause a problem.

Answer 22

Anatomy of the linea alba Linea alba = the convergence of the internal oblique, external oblique and transverse abdominal muscles. - widest in the cranial abdomen - attachment via the **pre pubic tendon** to the pubis

Answer 23

Locations of hernias 1. Cranial ventral midline of the abdomen - umbilical hernia - substernal hernia 2. Lateral hernias - paracostal defects - dorsal lateral hernias 3. Caudal hernias ventral midline - congenital scrotal - inguinal hernias 4. Traumatic hernias - pre pubic hernia - femoral hernia

Answer 24

**Pathophysiology of hernias** It is imperative for prognosis to manage the sequelae of organ herniation. **Space occupying defects "Loss of domain"** - the abdominal wall tightens over time - as it becomes accustomed to a smaller volume due to organ displacement. - manual reduction of organs becomes difficult - may result in tension during closue + poor organ perfusion (abdominal compartment syndrome). **Incarceration** Luminal obstruction of hollow organs (uterus, bladder, intestine) - high mortality with intestinal incarceration, especially when hernia is similar in size to intestinal lumen (may cause strngulation within hours) - less concern with uterine incarceration **Strangulation** Herniated contents are incarcerated and undergoing devitalisation - early venous obstruction - reversible organ enlargement - later arterial obstruction - irreversible organ necrosis - organ rupture Note; Traumatic hernias may have delayed incarceration and strangulation.

Answer 25

The four aims of hernia 1. Return contents (ensure viability) 2. Close hernia ring to prevent recurrance 3. obliterate redundant tissue eg, excessive peritoneal tissue 4. Provide a tension free and secure closure + use patient own tissue where ever possible.

Answer 26

Abdominal hernias Clinical signs - may be asymptomatic - may present with vomiting - swelling - abdominal pain There are three main presenting groups of abdominal hernias. Young dogs (scrotal hernia) - mostly male (narrow inguinal canal) - high incidence of strangulation (small intestine) - dark swelling on caudal aspect of scrotum - strangulation causes pain and inflammation Mature female dogs - mostly female dogs (wider shorter inguinal canal) - obesity and hormonal factors can widen the inguinal ring - low incidence of strangulation - usually soft painless swelling in inguinal region - unilateral or bilateral. Traumatic

Answer 27

Caudalabdominal hernias are either direct or indirect ? Indirect - more common - viscera enter the cavity of the vaginal process - scrotal hernias usually cause organ dysfunction due to the narrowing of the vaginal process at the relatively inelastic inguinal ring. Direct - less common - organs pass through inguinal rings adjacent to the evagination of the vaginal process - large hernias which do not usually result in strangulation or incarceration.

Answer 28

Incisional hernia - surgical error usually Management 1. Avoid debridement if possible 2. Any tissue which is devitalised or grossly contaminated must be removed 3. early aggressive supportive therapy 4. use sterile banadges to reduce further contamination and tissue damage 5. Elizabethan collar 6. Sterile flush is superficial contamination 7. deep contamination - open peritoneal drainage 8. monofilament prolonged absorbable sutures Aftercare - reduce exercise for a minimum of two weeks - poor prognosis = high lactate - good prognosis in the absence of shock and peritonitis.

Answer 29

Rational plan for abdominal hernias (always reccomend a neuter as there is a genetic predisposition). Conservative treatment - <2-3 mm in size in a young animal - spontaneous closure < 6months of age Surgical treatment - always address surgically at the time of diagnosis if hernia is approximately the width of a finger / small intestine/ - Scrotal hernia = surgical emergency - high risk of strangulation / incarceration as the vaginal process narrows.

Answer 30

Bladder Anatomy - The bladder is attached to the abdominal wall by the **ventral median ligament.** - ventral median ligmament contains the urachus - often transected during cystotomy - lateral ligaments contains the distal portion of the ureters and the umbilical artery Histopathology - distensible organ made of transitional epithelium - detrusor muscle (smooth muscle) surrounds the bladder.

Answer 31

Vascular supply to the bladder The vascular supply enters the bladder dorsally. main supply caudal vesicular artery - arising from the uterine or prostatic artery Cranial vesicular - terminal ending of the umbilical artery. Take home message - avoid dissection dorsal to the bladder where possible.

Answer 32

Physiology of micturition **Storage of urine = sympathetic control** hypogastric nerve - alpha adrenergic stimulation = contraction of the internal urethral sphincter - beta adrenergic stimulation = relaxation of the detrusor muscle **Voiding of urine = parasympathetic control** Pelvic nerve - bladder becomes fill which innervates sensory fibres within the detrusor muscle - motor portion of the pelvic nerve causes contraction of the detrusor muscle. **Pudendal nerve = voluntary control** - voiding is inhibited by contraction of striated muscle distal to the bladder

Answer 33

Healing of the bladder Healing - bladder mucosal defects heal within five days - full thickness defects heal to 100% strength within 14-21 days layers of the bladder - Four layers; mucosa (transitional epithelium), submucosa connective tissue, muscular layer and serosa. - holding layer = submucosa

Answer 34

Closure of the bladder post cystotomy The holding layer is the submucosa - avoid suture penetrating the lumen (nidus for urolith formation) - serosal patching should be considered in a diseased bladder - glentle tissue handling is paramount (use debakey forceps) - can use interupted or continuous - ventral incision is easier as the vasculiture is dorsal polydioxanone PDS or polyglyconate (maxon)

Answer 35

Cystotomy We usually do not require antibiotics - not required as urine is sterile (clean contaminated - infection rate is around 5% and this can not be reduced with the use of antibiotics In complicated or prolonged surgery consider antibiotics - amoxycillin + clauvulanic acid or third generation cephlasporin - E.coli, Staphylococcus, proteus

Answer 36

Biochemical testing to confirm a uroabdomen Abdominocentesis Atleast two of the following criteria must be met 1. The effusion creatine is >4x the serum creatine 2. The effusion ; serum creatine ratio >2 3. The effusion: serum potassium ratio > 1.4 We do not use urea as it freely diffuses

Answer 37

Cystostomy Making a hole in the bladder to remove fluid or place a tube. 1. Determine if the penis is inside or outside of the surgical field (douche the prepuce and surgically prepare). 2. Empty the bladder (syringe and needle) 3. Gentle tissue handling (mucosa becomesodematous) - ice water to prevent swelling - avoid diathermy - appropriate instruments debakery forceps atraumatic + metzenbaum - incision unbilicus to caudal pubis - prevent contamination - isolate the bladder from the abdomen - stay sutures and assistant to elevate the bladder - lap sponges keep tissue moist + prevent spill into abdomen - remove stones autoclaved teaspoon - pressure test prior to closure

Answer 38

Diagnostic test - ruture of urinary tract. Ultrasound - wall thickness, lesions, uroliths - free fluid within the abdomen Abdominocentesis (@@-24 guage needle) Atleast two of the following criteria must be met 1. effusion creatine 4x that of serum creatine 2. ratio of effusion : serum creatine >2 3. the ratio of effusion: serum potassium >1.4 Antegrade + retrorade pyelography - allows for the identification of the site of rupture.

Answer 39

Comparative anatomy of the urethra cat vrs dog. Male dog urethra is divided into three parts **The pre- prostatic urethra** - lies within the pelvic canal - closely associated with the bladder neck - transitional epithelium **Membranous urethra** - from the prostate to the bulb of the penis **Cavernous urethra (penile urethra)** - epithelium changes to stratified squamous epithelium near the external urethral sphincter. The male cat urethra is divided into two parts. **Pelvic urethra** - pre-prostatic - contains three layers of smooth muscle (circular + long) that contribute to a relatively long internal urethral spinchter - prostatic and and post prostatic **Penile urethra** - transitional epithelium gradually changes to stratified epithelium in the caudal 1/4 of the urethra - the feline urethra narrows as it enters the penis, predisposing males to urinary obstructions

Answer 40

Female dogs and cats urethra - not divided into areas - transitional and stratified squamous epithelium - cranial 2/3 is smooth muscle / internal urethral sphincter - caudal 1/3 is striated muscle, the external urethral sphincter.

Answer 41

Placing a catheter in a bitch Materials - Foley catheter - sterile gloves - sterile - soluble lubricant - antiseptic solution (diluted on guaze squres- no scrup) - 12ml syringe with diluted chlorhexidine solution for vulva flush Methjod 1. Douche aseptic solution preparation of the vaginal vault and outside area is vital prior to catheter placement. 2. position patient in ventral recumbency with hind legs off the edge of the table 3. use finger (sterile gloves) to palpate papillae or urethral opening - to serve as a guide for the catheter to follow 4. after placement use a closed collection system, and proper aseptic care of the catheter and lines.

Answer 42

Healing of the urethra Urethral mucosa can regenerate quickly within 7 days - seven days are required for epithelial repair - 21 days required for the return of submucosal supporting factors - no clinical signs of stricture until there is a 60% reduction in lumen diameter. Factors which negatively affect healing - Mucosal continuity and urine extravasation are the main factors that influence healing - if a urethral strip remains and urine is diverted then healing may occur.

Answer 43

Urethrostomies Dogs = urolithiasis, cats FLUTD continued urine production in the face of obstruction leads to increased pressure in the ureters, renal pelvis and renal collecting system. Normal 0-10mmhg abnormal = 50mmhg - can result in renal damage Urethrostomies A incision is made in the urethra to allow removal of urolithis 1. scrotal urethrostomy (most reccomended) - the urethra in the scrotal region is relatively superficial and wide 2. Pre-pubic urethrostomies 3. pubic urethrostomies 4. Perineal urethrostomie (rare cats) 5. Penile urethrostomie Note the urethra contracts 1/3 to 1/2 during healing.

Answer 44

The different types of uroliths primarliy organic or inorganic crystalloid and a much smaller amount of organic matrix. **1. Calcium oxalate** - colourless octahedral - now the most common type of urolith encountered **2. Struvite uroliths ** - colourless coffins **3. Ammonium biurate** - PSS, or dalmations **4. Silica** **5. Calcium phosphate** **6. Cysteine (less soluble in acidc urine)** **7. Ammonium urate **

Answer 45

**Risk factor for the development of uroliths** **Calcium oxalate pathophysiology** - prevalence is increasing - may be due to Mg decreased in commercial foods - uteroliths most likely CaOX in cats, older neutered males - independant of PH - hypercalciuria - hyperoxaluria - increased concentration - decreased volume and urine retention **Struvite (as pictured below) risk factors** - decresaing over time with commercial diets - alkaline urine - females more than males - neutered and younger - increased Mg - concentrated urine

Answer 46

**Know the radiodensity of each stone** Consider likely stone and adjust your diagnostics accordingly Radio opaque stone - calcium oxulate - calcium phosphate - struvite - silica Less radio opaque - systine - ammonium biurate - uric acid - I can not see u

Answer 47

Surgical options for uroliths Indications - obstruction - renal pain - recurrent infections - progressive enlargement Renal urolith - extracoporeal shock wave therapy - nephrotomy - percutaneous nephrolithotomy Ureteral uroliths - subs - stents - extracororeal shockwave therapy - ureterolithotomy - neoureterocystomy Bladder and urethral uroliths - urethral hydropulsion - cystotomy - lithrotripsie - urethrostomies - basket retrieval

Answer 48

Indications for urolith surgery - obstruction - recurrent infections - renal pain - progressive enlargement

Answer 49

The pathophysiology of a perineal hernia Perineal hernia develops due to weakness and seperation of the pelvic diaphragm components. This leads to dilations of the rectum and caudal protrusion of organs; prostate, bladder, omentum, jejunum or paraprostatic cyst. The cause of PH is still unclear, but potentiall aetiologies include; 1. Congenital predisposition 2. rectal abnormalities 3. hormonal imbalance - relaxin, testosterone 4. structural weakness of the pelvic diaphragm (short tailed breeds) with underdeveloped levator ani and coccygeus muscles. 5. chronic straining due to various causes. 6. prostatic enlargment. Any factor precipitating straining to defaecate, against a weakened pelvic diaphragm may precipitate development of a perineal hernia.

Answer 50

Anatomy of the pelvic diaphragm Muscles 1. levator ani muscles 2. coccygeus muscle 3. external anal sphincter 4. internal obturator muscle Innervation caudal rectal nerve - sole innervation to the external anal sphincter. Function - to provide support for rectum and other structures as they transverse the pelvic canal - to maintain abdominal contents within the abdomen, not the pelvic canal.

Answer 51

Categorize perineal hernias based on their location. Perineal hernia 1. Caudal - between the levator ani, external anal sphincter and internal obturator. 2. Ventral 3. Lateral 4. Dorso lateral

Answer 52

Perineal hernia The Levator ani is the most common muscle atrophied / absent. Most common location = caudal perineal hernia - between the levator ani, external anal sphincter and internal obturator.

Answer 53

Upon clinical examination Upon identification of the clinical signs - perineal swelling - signs of constipation / urinary obstruction the clinician should carry out a rectal exam of their patient. To diagnose a perneal herniation: rectal exam - lack of rectal support - finger can pass laterally just inside the anus - check both sides - diagnostic To identify the cause - ultrasound, prostate and hernial contents - abdominal rad - size of prostate, megacolon, bladder position - barium meal assess hernia contents.

Answer 54

1. Perineal repair - Traditional herniorraphy **Standard technique Re-appose muscles of the pelvic diaphragm** and castrate - various suture materials used - preplace all sutures before tying 1. coccygeus muscle 2. levator ani muscle 3. internal obturator muscle 4. external anal sphincter - position in sternal recumbancy - preserve pudendal nerve (overlies the internal obturator muscle) - adhesions can be severe - gentle, aseptic technique - repair both sides if nessary 2. Why should we consider alternative techniques - problem - muscle weakness poor suture holding power - absence of muscle to suture = tension - these issues often lead to dehesiance of the surgical site.

Answer 55

Surgical correction of a perineal hernia Pre-surgical - bloods + urinalysis (a retro flexed bladder is a medical emergency) - enemas are contraindicated causes soft faeces - periop antibiotics - remove faecal material + empty anal sacs and pack rectum with gauze +/1 urinary catheeter - purse string suture Surgical consideration surgery site is in close proximity to a number of vital anatomical structures - sciatic nerve - pudendal nerve (overlies the internal obturator muscle) - caudal rectal nerve (sole innervation to the external anal sphincter) - retroflexed bladder = medical emergency post surgical consideration - painful procedure ensure pain relief is covered - remove purse string suture - digital rectal exam to check for adequate rectal support - use medication to reduce straining - low residual diet - +/- antimicrobial treatment

Answer 56

Innervation of the external anal sphincter. Caudal rectal nerve Sole innervation to the external anal sphincter incompetance.

Answer 57

Perineal repair = traditional heriorrhapy weakened perineal diaphragmatic muscles makes the surgical site likely to break down. Alternative surgical techniques 1. transposition of the internal obturator muscle 2. prosthetic mesh repair / non autogenous 3. transplantation of the semitendinosus Good prognosis if done early and by an experienced surgeon.

Answer 58

When correcting a perineal hernia castration is essential. 2.7x the risk of reccurrance in an entire male

Answer 59

Post operative complications 1. wound infection 2. faecal incontinence 3. urinary tract malfunction 4. tenesmus 5. sciatic nerve paralysis 6. recurrance of hernia (reduced through castration) 7. rectal prolapse

Answer 60

Diaphragmatic anatomy Musculotendinous partition that seperates the abdominal and thoracic cavity. composed of muscles; - pars sternalis - pars costalis - and paired lumbar muscles Apertures and what passes through them. Caval foramen - vena cava Oesophageal hiatus - oesophagus and its blood supply - dorsal and ventral vagal trunks Aortic hiatus - aorta - azygous - hemiazygous vein - lumbar cistern thoracic duct

Answer 61

**Surgical approaches** Surgery carried out at the earliest opportunity in a stable patient. Early surgery for acute diaphragmatic herniation is associated with a good prognosis. **Lateral thoracotomy** - mandatory to perform incision on the side of the 'hernia' - can not be used for bilaterally sided hernias - contraindicated for peritoneopericardial hernia **Median sternotomy** - allows extension of a midline coeliotomy - adhesions can be visualised and trasected **Midline coeliotomy** - Indicated for most traumatic peritoneopericardial hernias - less important to know the exact position of the diaphragmatic repair Problems - difficult to breakdown intrathoracic adhesions - difficult to suture on a concave surface ** Recommended surgical approach ** midline coeliotomy - provides the greatest visualistaion - if there are significant adhesions may extend the surgical incision into a median sternotomy.

Answer 62

Diaphragmatic hernia Pathology - usually a result from trauma (85%) - direct - indirect thought to occur to a sudden increase in intraabdominal pressure with the glottis open. Leads to herniation of the viscera into the peritoneal to pleural pressure gradient. - rupture of the diaphragmatic costal muscles are more common than the central tendon - dog radial 40%, cats circumcostal 59% Clinical signs (dyspnea is the most common clinical sign). **Apex beat absent on the side of the hernia.** -cardiorespiratory - incarceration - strangulation (creation of bands and adhesions). - obstruction Diagnoses - ultrasound - radiographs - CT, MRI (radiograph all trauma patients = partial loss of the line of the diaphragm).

Answer 63

**Diaphragmatic hernia** Upon surgery one lung may remain partially or completely collapsed - Do not rapidly reinflate. **Rapid reinflation** - causes massive mechanical stress on the lung - this can lead to oedema, haemorrhage or pneumothorax - inflammatory response - increased capillary permeability in lungs - cells of herniated organs switch aerobic to anaerobic metabolism - organs are returned to abdomen rapidly reperfused - creation of superoxide free radicals - cell death results = poor prognosis **How do we prevent rapid reinflation** - leave a small amount of air in the thorax - intermittent suction drainage with a syringe - allow lung to gradually inflate over 8-12 hours - thracostomy tube placement **(intra abdominal pressure 3-5mmhg)**

Answer 64

**Congenital peritoneopericardial hernia **Pathogenesis** - common congenital abnormality of dogs, not inherited embryological mistake. - abnormal development of the transverse septum - thin or absent ventral diaphragm - present at birth and often goes undiagnosed for years. - no direct involvement with the pleural space - organs involved; liver, falciform, omentum, spleen, SI, spleen and rarely the stomache - cardiac tamponade Clinical signs - often asymptomatic - respiratory insufficiency from indirect pulmonary compression - incarceration, obstruction and strangulation of intestinal organs - weight loss, abdominal pain, ascites - muffled heart sounds, cardiac murmurs abnormally positioned heart sounds Diagnosis Rads - enlarged cardiac silhouette Ultrasounds - most useful ECG - low amplitude complexes and electrical alterans

Answer 65

USMI Primary sphincter mechanism incompetance - larger dogs / adult spayed female Clinical signs Incontenance that only occurs when lying down, any other time of incontenance eg walking excludes this as a diagnosis. - incontenance when laying down - Pu/PD - perivulval dermititis - vaginitis Diagnosis - signalment and history - retrograde pyelograph; position of bladder, to rule out ectopic ureters - cystoscopy - ultrasound specialist diagnostics

Answer 66

The three main causes of USMI **1. Hormonal** - oestrogen deficiency - evidence based on oestrogen therapy - early neutering causes a reduction in circulating hormones oestrogen, which healp to maintain the sensitivity of adrenergic receptors (sympathetic nervous system - catecholamines epinephrine) - oestrogen receptors in the urethra increase sensitivity to catecholamines - catecholamines increase urethral tone - early neutering may cause USMI / conflicting information. **2. Structural** - shorter urethra +/- bladder neck position - - bladder is positioned more caudal compared to continent dogs - urethral length is shorter - less of the urethra functios as a sphincter - urethral pressure profilometry - difference in closing pressure ** Functional ** - Lower closing pressure - urethral tone = smooth and skeletal muscle - connective tissue differences - less collagen and muscle volumes - oestrogen deficiency may reduce smooth muscle tone, and may also affect urethralis (reduce type one, two muscle fibres)

Answer 67

How urinary continence is maintained in the bitch. 1. External sphincter = urethral striated muscle tone 2. Internal sphincter = urethral smooth muscle tone 3. Natural elasticity of te urethral wall 4. Physical properties of the urethra = length and diameter 5. degree of engorgment of the suburethelial venous plexus.

Answer 68

**Medical management of USMI** Most therapies only address one cause (hormonal, structural, functional) - thus there is only a 50% chance of a cure. Note 50% of juveniles will be continent after the first oestrus. Oestrogen - sensitizes the urethra to alpha adrenergics - urothelium more compliant - bone marrow suppression Alpha adrenergics (Phenylpropanolamine) (best option) - increased urethral tone - 85.7 response rate - only a 28 day follow up - profilometry found significant changes in pressure after treatment GNRH analogues - gonadotrophic releasing hormone - down regulate pituitary gonadotrophins - 50% of bitches are continent

Answer 69

Surgical options for USMI Surgery serves to address one of three things 1. Increase urethral resistance (slings, bulking agents, sphincters) 2. relocation of the bladder neck into a intra-abdominal position 3. increase urethral length **Colposuspension** - Based on short bladder neck therory - vagina 'partial thickness' is sutured to the prepubic tendon - relocate the bladder neck into the intra abdominal position - 50% success rate - lengthening of the urethra - more cranial position of the neck of the bladder. **Periurethral injections ** - cystoscopy and filler used to increase urethral resistance - endoscopic injection - increase urethral tone AUS Artificial urethral sphincter - Percutaneously contralled static hydraulic urethral sphincter - continence 70%

Answer 70

**Maintenance of continance in the bitch** - external urethral sphincter = urethral striated muscle - internal urethral sphincter = urethral smooth muscle tone - natural elasticity of the urethral wall - physical properties of the urethra - length + diameter - degree of engorgment of the suburethral venous plexus How surgery enhances continenece - Colposuspension = increase urethral length by moving the bladder cranially Periurethral injections = increase urethral tone, requires ongoing treatment Urethropexy = increase urethral length Artificial urethral sphincter AUS = percutaneously controlled

Answer 71

**Anatomy of the prostate** Dog - bilobed structure completly encircling the proximal urethra Cat - partial encircling of the urethra Function - unknown but thought secretions produced to promote sperm mobility and viability. The prostate has a peritoneal covering Location - ventral to the prostate is the pelvic symphasis, lateral pelvic wall and laterally the ventral aspect of the rectum Blood supply - internal pudendal artery branching off is the prostatic artery. Innervation - pelvic nerve - vesical plexus (dorsal)

Answer 72

Why surgery of the prostate is seldom performed Surgery of the prostate is rarely performed; 1. Urinary incontenance - common complication, due to close proximity enclosing the urethra in dogs (high risk of damage. 2. Vesicular plexus (pelvic nerve) - high prostatic vascular plexus and pelvic nerve on the dorsal aspect of the prostate making access difficult. - haemorrhage - deinervation 3. Difficult to access (location) - ischium is ventral and the colon is located dorsally, making clear visualisation and access difficult. 4. Metastic rates of prostatic cancers are high - at the time of diagnoses, significant mets; making surgery rarely beneficial.

Answer 73

Differential list for the prostate - Benign prostatic hypertrophy (BPH) - prostatitis - Prostatic and paraprostatic cyst - prostatic neoplasis (usually malignant)

Answer 74

Benign prostatic hypertrophy (BPH) BPH prostate undergoes spontaneous androgen mediated enlargement - hypertrophy increase in cell size - >95% intact older males - dyschezia (difficulty to daefaecate) - penile discharge - pain on palpation of the abdomen - prevention = neutering Diagnosis - rectal palpation enlarged symetrical bi lobed prostate - no significant pain Unltrasound (best) - heterogenous increase in ethogenicity Rads - displacement of colon or bladder incisional biopsy Treatment Castration - causes 70% decrease in the size of the prostate - usually takes 7-14 days, but may take upto four months - stool softeners. - valuable breeding animal = finasteride

Answer 75

**Prostatitis ** Acute bacterial prostatitis may cause acute pain. - chronic prostatitis may be asymptomatic - recurrent UTIs - urethral discharge - prostatic abscessation is the sequelae to chronic prostatitis (cavities of purulent fluid found within the parenchyma). Diagnoses - rectal exam - ultrasound = highly chracteristic hyperechoic lobulated tissue - rads = emphasematous change - transurethral wash, cytology and microbiology. Treatment - castration and antibiotics - infections resolved more quickly in castrated dogs - surgical stroma drainage - enrofloxacin

Answer 76

prostatic cyst = fluid filled pockets within the prostate paraprostatic cyst = pockets of fluid adjacent to the prostate. The cyst often are associated with BPH and are formed when canaliculi become obstructed leading to the accumulation of prostatic fluid. Clinical signs - consistent with a caudal pelvic mass - strain to defaecate or urinate - abdominal distension - often patients are asymptomatic

Answer 77

Prostatic and paraprostatic cyst Diagnoses - patients are frequently asymptomatic or they have symptoms consistent with a caudal pelvic mass. - ultrasound = hyperechoic fluid pockets Management - drainage via ultrsound guidance and castration - paraprostatic cyst = resection of the cyst or partial resection of the cyst and omentalisation.

Answer 78

Prostatic neoplasia Clinical signs - generally uncommon in dogs, presenting in older animals - not prevented through castration - usually adenocarcinoma or transitional cell tumour Diagnoses - prostate enlargement palpated on rectal exam - sometimes elevated ALP and Ca - skeletal metatasis - rads minerlisation of the prostate is indicative. - 44% of dogs have mets - ultrasound = heterogenous hyperechogenic changes Treatment - partial or complete prostatectomy and radiation therapy - laser filleting technique will allow preservation of the urethra. - poor prognosis due to the aggressiveness of the tumour

Answer 79

Anatomy of the heart and pericardium. All but the most dorsal aspect of the heart is covered in pericardium - right side thin walled compared to the left - phrenic nerves transverse the pericardium (phrenic nerves can be severed and the patient will still ventilate). - heart located between the 3rd and 6th intercostal space. Pericardium is composed of two layers Fibrous pericardium - outer layer - Serous pericardium - inner layer of the pericardium

Answer 80

The functions of the pericardium 1. Maintains the heart in a normal position 2. Prevents overdistension - restrains cardiac filling (diastolic ventricular coupling) 3. balances the output of the right and left ventricles 4. protects againts atrial rupture 5. prevents the spread of neoplasia and infection 6. provides a gliding surface - for frictionless movement.

Answer 81

**Pericardial effusion **Indications for surgery -** cardiac tamponade - diminished heart sounds - distended jugular veins - ascites ** Surgical options** Approach left lateral thoracotomy through 4th -5th ICS 1. Periocardiocentesis - drain the fluid within the pericardium to stabilise patient 2. Percardial fillet - removal of a small section of the pericardium to allow it to drain 3. Subphrenic pericardectomy -nremove pericardium from the heart bilateral upto the level of the phrenic nerve to allow for constant drainage of benign pericardial effusion ** Complications** - recurrance - herniation - restrictive cardiopathy - ventricular fibrillation (no electrocautery) - death

Answer 82

Pericardial effusion Clinical findings - acute hypotension - lethargy, dyspnoea - weakness / collapse - muffled heart sounds - cardiac tamponade - can not pump enough blood constricted - distended jugular veins - Pulsus paradoxus = ausculated heart beat without a pulse upon inspiration (dropped pulse) - Ultrasound - ECG - reduction of the QRS complex Immediate treatment - pericardiocentesis - then follow by treating the underlying cause eg infection - stabilise patient with oxygen.

Answer 83

Patentent ductus arteriosus Presentation - young animal with shunted growth - water hammer pulses (excessive visable bounding) Diagnosis - age and water hammer pulses **radiograph** cardiomegaly + dilated pulmonary arteries - dorsal elevation of the trachea **Echocardiography** **ECG **- tall T waves Treatment - coil embolization - ligation

Answer 84

Patent ductus arteriosus blood flow Foetal ductus arteriosus - in the foetus blood is allowed to bypass the lungs - conduit between the main pulmonary artery and aorta - the conduit closes shortly after birth (48hrs to one month) Patent ductus arteriosus (left to rigjht shunt) - volume overload to the left side of the heart - dilation of pulmonary veins and arteries - left sided heart failure - reccomend surgery 70% mortality by one year of age Cyanotic PDA (right to left shunt) - is a reversal of the shunt - pulmonary pressure reverses the shunt - deoxygenated blood enters the aorta - cyanosis caudal (hindlimb cyanosis) - cyanotic PDA surgery no longer indicated.

Answer 85

Treatment options for a patent ductus arteriosus medical management = frusimide reccomend surgery 70% of patient die before one year of age - specialist Ligation - left thoracotomy in the 4th intercostal space - ligation of the patent vessel - successful surgery is usually curative. Coild embolization - can be passed up the femoral artery - slow occlusion of conduit

Answer 86

Anatomy physiology of the oral cavity and its consequences on surgery 1. Excellent blood supply - surgery can be associated with significant haemorrhage 2. Multiple bacterial species present (antibacterial nature of saliva aids in balance) 3. High tension on suture lines - high incidence of break down 4. Post surgery bypass feeding to protect the suture lines through a osteophagostomy. Nervous supply facial (7) and trigeminal (5) Blood supply lingual artery, a branch of the external carotid.

Answer 87

Muscles of the tongue - styloglossus - hyoglossus - genioglossus

Answer 88

Muscles of the soft palate levator veli tensor veli - enable the animal to elevate and tense the soft palate - these muscles are known to degenerate with brachy cephalic syndrome.

Answer 89

Sentinel lymph node mapping (methylene blue, iohexol) Lymph nodes of the mouth - mandibular - retropharngeal - superficial cervical Lymph node mapping The use of dyes and radioactive substances to identify lymph nodes that primarily drain a tumour (may contain cancer cells) - injection of a contrast agent into the area of interest (tumour) - the sentinel lymph node can be can be different **locoregional lymph node.** - locoregional lymph node is the lymph node expected to drain an area based on anatomy. - Sentinel lymph node the lymph node that actually drains the tumor site. - there can be multiple lymph nodes in a lymph centre and multiple sentinel lymph nodes - lymph may even cross the midline Identification of the sentinel lymph node is prognostic and its removal can be therapeutic. Imaging modalities - radiography lymphography - CT lymphography - contrast enhanced ultrasound

Answer 90

The major lymph nodes of the oral cavity 1. medial retropharyngeal 2. mandibular 3. parotid 4. all of these lymph nodes drain to the superficial cervical. (can have multiple glands at each site) The lymphatic drainage from the head = mandibular and medial retropharyngeal lymph nodes (occassionally parotid) - the lymphatics drain extravascular fluid back to the heart - transports white blood cells, fat from intestines - the lymph passess through nodes which produce immunoglobulins in response to disease.

Answer 91

Neoplasia of the tongue Common types - malignant melanoma - squamous cell carcinoma - fibrosarcoma - osteosarcoma - the neoplasias have an overall malignancy of 90% - the size of the tumour affects prognosis - often have metastatic spread to local lymph nodes and lungs Surgical options Glossectomy - tolerated well in dogs - cats are less willing to adapt to changes in their oral structure

Answer 92

Know the role of surgery in the management of the following oral cavity diseases; Pre operative preparation of the oral cavity, Surgical options - 1. Palate disease / defects - sliding flap technique - hinged pouch technique 2. oral neoplasia - unilateral or bilateral mandibulectomy - surgical margin oral cavity 2-3cm bone and 1 cm soft tissue - radiation therapy - chemotherapy 3. salivary gland disease Sialadenitis = phenobarbital medical management Sialococele = drainage via needle and removal of the mandibular and sublingual glands on the affected side is successful.

Answer 93

Hard palate defects Congenital defects = are present at birth due to genetic or environmental abnormality - 'hair lip' the lip and premaxilla - ' cleft palate' Aquired defect of the hard palate are due to trauma - oronasal fistula - acquired foreign body, stick injury - or dental associated oronasal fistula.

Answer 94

Surgical correction of the hard palate **Presurgical considerations** -can not achieve aseptic surgery - may rinse mouth with a diluted antiseptic - ensure ET tube is inflated - pahryngeal packing - palatine artery and mandibular palatine artery (alot of bleeding is expected) **Surgical principles** - aim for a multiple layer closure - suture through bone tunnels when possible - tension relieving incisions is crucial - preserve blood supply - major palantine artery - overlapping flaps when large bony defects are present. **Surgical approach x2** - Sliding flap technique - hinged pouch technique

Answer 95

**TMN = staging spread of the cancer** A system used to describe the amount and spread of cancer in a patients body. (tumour size, metastatic spread and node involvement) The stage depends on the tumour type and its location. TMN staging for a malignant malinoma (most oral tumours are highly malignant) **Stage one T1, NO, MO** - tumour is less than 2cm - no evidence of retropharyngeal lymph node involvement - no signs of mets - prognosis with surgery one year ** Stage two; T2, NO, MO** - tumour 2-4cm in size - no signs of lymph node involvement - no signs of mets - prognosis with surgery approximately six months **Stage three; T2, N1, MO or T3, N0,M0** - small tumour <2cm with lymph node involvement - large tumour >4cm but no lymph node involvement - no metatitisis - prognosis with surgery is approximately three months survival time **Stage four; antT, anyN and M1** - tumour any size - possible lymph node involvment - mets is present - with surgery approximate survival time of one month.

Answer 96

Standard approach to a tumour investigation Grade Type and aggressiveness of the tumour - cell type - mitotic index - requires a biopsy Stage - spread of the tumour The grade and stage changes treament and prognosis - TMN Removal of the tumour may occur prior to grading, if grading of the tumour is umlikely to change the treatment eg oral tumours.

Answer 97

Mandibular excisions: tumour removal Terms; - rostral hemimandibulectomy (unilateral) - rostral hemimandibulectomy (bilateral) - central hemimandibulectomy - caudal hemimandibulectomy - full mandibulectomy A similar classification scheme is used in the maxilla Know the surgical dose; The reccomended surgical dose, is the amount of surgery required to achieve a desired outcome - surgical dose remove tumour margins - 2-3 cm of bone and 1cm of soft tissue for treatment of oral tumours.

Answer 98

Dogs have four pairs of salivary glands; 1. Parotid 2. Zygomatic 3. Mandibular 4. Sublingual

Answer 99

Sialocoeles Sialocoeles - leakage of salive due to ruptue of glands / ducts. salivary mucocoele = leakage of saliva into the surrounding tissue Four common presentations of sialocoeles 1. exophthalmos (zygomatic sialocoele) 2. laboured breathing 3. dysphagia 4. cervical and intermandibular swelling - soft and painless Usually caused by leakage from the mandibular or sublingual salivary glands. Diagnose through aspirating saliva Surgical correction of an sialocoele - drain the mucocoele with aneedle and spirate - for most cases removal of the mandibular and sublingual salivary glands on the affected side side is successful.

Answer 100

The anatomy of the oesophagus The oesophagus is composed of four layers; 1. mucosa - stratified squamous epithelium 2. submucosa 3. muscularis 4. adventitia Lacks a serosa but mesothelial covering substitutes. Nervous supply - closely assciated with the vagus Blood supply - cervical cranial and caudal thyroid arteries - caudal oesophageal branches of the aorta + intercostal arteries - blood supply is segmental - rich submucosal anastosmosing network is present. The specific anatomy of the oesophagus causes high rates of post operative complcations **Five reasons for high rates of post operative complications.** 1 Lack of serosa (fibrin seal and pluripotent stem cells) 2. Segmental nature of blood supply - intramural blood supply and collateral segmental supply must be preserved, ligation of both the cervical and thoracic blood supply causes necrosis. 3. Lack of omentum or other vascular tissues which can be used for patching 4. Constant motion - caused by swallowing and respiration (gastric tube may be placed, food and water is withheld for 24 hrs to 7 days orally. 5. Tension at the surgical site. In the abdomen serosa assists with healing with elaboration of a fibrin seal by providing pluripotential mesothelial cells. In the thoracic cavity mesothelium may play a similar role.

Answer 101

Oesophageal obstruction (regurgitation) (mortality 5.4% with oesophageal strictures) - regurgitation, salivation and inapetance. - ulceration and oesophagitis. Common causes of oesophageal obstruction - most common chop bones (sharp) - dental chews in small dogs - the most common places to become lodged; thoracic inlet, heart base and caudal oesophagus Surgical management of oesophageal obstruction. Pull out vrs push down vrs surgery Pull out - endoscope and specialised grasper essential to remove foreign body - best option - not always possible due to reach and ability to grasp object Distal oesophagus - can attempt to push into stomach - large stomach tube eg equine If these options fail thoracotomy indicated Post operative considerations - carefully inspect oesophagus for signs of perforation or ulceration - gastrostomy tube to rest oesophagus - proton pump inhibitors worse prognosis in older animals, longer duration of obstruction or perforation.

Answer 102

PRAA Vascular ring anomaly Persistant right aortic arch Congenital abnormality of the major vessels at the heart base can result in compression of the oesophagus by vascular structures - most commonly is persistant right aortic arch (PRAA). Clinical signs - clinical signs develop soon after weaning - regurgitation of food and fluid - if left untreated, oesophagus becomes filled and dilated with food just cranial to the site of obstruction at the heart base.

Answer 103

PRAA persistent right aortic arch Clinical signs - young animal just after weaning - regurgitation of food and water - diagnosis rads and barium Surgical recommendation - hereditary condition must reccomend neutering - good results if treated early by 4th-5th ICS thoracotomy and transecting the ligamentum arteriosum. Prognosis - persistent regurgitation is common - aspiration pneumonia is a life long risk - 1/5 of dogs do not respond to surgery - 8% die intraoperatively, and 18% will die in the first two months post surgery.

Answer 104

Principle of surgery for the oesophagus approaches to the oesophagus Cervical oesophagus easily approached ventrally on the left of the trachea Thoracic approach varies depending on the area requiring access - cranial thorax left or right intercostal sternal - caudal thorax left ICS 7,8 or 9 Surgical principles (5) - gentle tissue handling - minimize contamination - accurate opposition of tissues - careful use of electrocautery - appropriate selection and use of suture materials Oesophageal suturing - submuscosa is the strength layer - 1 or two layers are acceptable (if two layers, mucosal layer knots within the lumen. - appositional suture patterns simple interupted

Answer 105

Higher complications associated with surgery of the oesophagus. 1. Lack of serosa (adventitia) - fibrin seal and pluripotent stem cells 2. Segmental nature of the blood supply - intraluminal blood supply and collateral segmental supply must be preserved, ligation of both thoracic and cervical blood supply will lead to necrosis. 3. Lack of omentum (or other easily accessable structures for suturing) 4. Constant motion - caused by swallowing and respiration - may use a G J tube placed and withhole food and water a minimum of 24 hrs and upto 7 days. 5. Tension at the surgical site - large amount of transverse stretch, but very little longitudinal.

Answer 106

Anatomical difference dogs and cats; oesophagus Dogs - striated muscle throughout - distant longitudinal folds Catschanges from striated to smooth muscle at the level of the heart base longitudinal folds change to transverse at the heart base. may give a herring bone appearance know this is not a pathology.

Answer 107

Anatomy of the stomach Anatomical structures - pylorus - fundus - body - cardiac ostium - oesophagus Blood supply - left and right gastric arteries - lesser curvature - left and right gastroepiploic - greater curvature arteries Cell types - parietal acid production - Chief pepsin - Endocrine - histomine and serotonin Anatomy of the stomach and its relevant effects on surgery 1. The stomach is highly vascular - expect haemorrhage 2. Clamp large vessels - avoid cautery 4. Expect the outer (serosa and muscularis) and inner (mucosa and submucosa) to seperate when incised.

Answer 108

Suturing principles within the stomach Gentle tissue handling - Debakey Suturing of the stomach - gentle tissue handling debakey tissue forceps - use polyglyconate, poliglecaprone - gastric wall readily divides into a inner (mucosa, submucosa) and out (muscularis, serosa layer) - the inner layer is incredible tough (holding layer) as it must withstand anything which is ingested. - Suture the two layers seperately (mucosa, submucosa) appositional suture pattern as it promotes accurate tissue opposition and rapid mucosal seal - appositional patterns, simple interupted, gambee - (serosa, muscularis) outer layer us a inverting pattern ( Connel, Cushing or Lembert) - inverting sutures are appropriate in the outer layer as the stomach lumen is large. - minimal adhesions due to serosal apposition and minimal exposed suture - security against leakage / serosal seal - rapid mucosal healing - minimal reduction in lumen diameter. Blood supply = approach Blood supply from the gastric and gastroepiploic vessels entering the lesser and greater curvature of the stomach. - additional supply gastrosplenic and short gastric arteries - The rapid turnover of gastric mucosa requires good blood supply for optimal healing - Place your incisions where the vessels are the smallest

Answer 109

How to assess for stomach viability Subjective criteria; 1. gastric wall thickness and texture via palpation 2. serosal surface colour (black, green not viable) 3. serosal capillary perfusion 4. presence of peristalsis The non viable wall is usually thinner than normal, and has a grey-green/black serosal colour. The seromuscular layer can be incised to evaluate for a blood supply. may also utilise flurosceine dye.

Answer 110

Female reproductive anatomy Three ligaments - the suspensory ligament - proper ligament - broad ligament Blood supply - ovarian artery arising directly from the aorta - left ovarian vein - drains through left renal artery - right ovarian vein drains straight into the vena cava - uterine artery and vein Ovarian pedicle = the suspensory ligament including its artery and vein. Mesosalpinx = a fold of the broad ligament which supports and wraps around the fallopian tube (oviduct), containing blood vessels, nerves and lymphatics essential to function. Vaginal process - pouch of peritoneum (inguinal canal) - where the round ligament inserts

Answer 111

Definitions Spaying ovariohysterectomy = surgical removal of the ovaries and the uterus Ovariectomy = surgical removal of the ovaries alone hysterectomy = (ovary sparing surgery) complete removal of the uterus while leaving the ovaries intact.

Answer 112

Ovariohysterectomy (Spay)

Answer 113

Complications of ovariohysterectomy Complication rate 19% dogs and 12% cats must counsil owners prior to surgery. (Not without risk) Immediate complications - haemorrhage from uterine or ovarian vessels - anaesthesia incidents - tissue reaction to suture material (leads to the formation of granulomas or fistulous tracts) - dehiscence or delayed healing Early complications post surgery - seroma formation (fluid accumulation in a dead space) - tracheobronchitis - oesophageal reflux (occurs in 20% of surgeries usually subclinical) - coughing - self trauma - damage to ureters Potential long term complications - recurrent oestrus (ovarian remnant) - stump pyometra - delayed haemorrhage - weight gain - urinary incontinence (decreased oestrogen USMI) - behaviour changes - fistulous tracts or stump granulomas - gossypiboma (foreign material left within surgical site)

Answer 114

Avoiding ovariohysterectomy complications. Owners can pre surgery - wash dog chlorohexidine two days prior Surgeons could - council owners regarding the risk of surgery - clip big prior to surgery = access - mental map procedure - be prepared electrocautery on standby - know your anatomy + practice suturing - pain and stress relief - discharge patient with instructions - follow up appointment to remove sutures + monitor

Answer 115

Reccomended care following routine desexing 1. provide written instructions to owner 2. provide a clean environment 3. check and claen wound regularly 4. Elizabethan collar 5. If over weight reduce caloric provision 6. book appointment to assess wound and remove stitches.

Answer 116

Reccomended method closure of the linea alba Closure of the linea alba = holding layer - know security is paramount / start and end with a surgeons knot 5 throws PDS - - add two throws at for the end of the continuous suture - continuous suture pattern - avoid the peritoneum as this increases the risk of adhesions - 5-7mm facial bites, and 3-4mm travel

Answer 117

Timming of desexing Dog > 25kg delayed neutering benefit Dog < 25 kg the timming of a spey has no effect As a clinician you must weigh up the relative risk, prevalnece and incidence of a developing disease. The overall benefits of spaying Overall gonadectomy increases the lifespan of animals - mammary tumours reduced 3-7x - transmisserable veneral tumour - cryptorchidism - ovarian cyst - BPH - uterine neoplasia - testicular tumours - pyometra / metritis - reduced roaming However desexing may predispose to - MCT - lymphoma - haemangiosarcoma - increased risk of CrCL rupture and elbow disease - may increase aggression in female dogs - USMI

Answer 118

Canine cryptorchidism Retained testicle Testes should be descended by 30-40 days approximately 4-5 weeks. However this process can take upto 6 months - only make a definitive diagnosis >6months - incidence 1-12% - canine cryptorchid has an increased risk of petella luxation, hip dysplasia, penile deviation and umbilical hernia - suspected to be hereditory - if bilateral cryptorchid the animal will be sterile due to inability to thermoregulate. Pathway of testicular descension - testicle starts dorsal abdominal wall adjacent to the kidney - travels through the inguinal ring pulled by the gabernaculum into the scrotum.

Answer 119

Anatomy of the stomach Portions of the stomach - pylorus, cardia, fundus and body Blood supply - right and left gastric arteries along the lesser curvature of the stomach - right and left gastroepiloic along the greater curvature of the stomach - between the greater and lesser curvature is avascular Cell types Parietal = acid Chief = pepsin The neck has mucous cells Endocrine = serotonin and histamine

Answer 120

Gastrostomy Indications - foreign bodie, biopsy, exploration and resection of masses Pre surgical considerations - 12 hours of fasting - rapid induction and intubation to avoid aspiration - oesophageal reflux 50% of cases - consider omeprazole prior to surgery H2 antagonist Surgical approach - Midline laparatomy ensure incision from xyphoid to pubis - isolate stomach Balfour retractors + stay sutures - pack with wet lap sponges ( avoid contamination) - stab incision avascular area (inbetween greater and lesser curvature of stomach). - **Pass Poole** is used for immediate suction and can be passed into the duodenum (prevents contamination) - the stomach is highly vascular expect haemorrhage (avoid electrocauter / clamp off) - expect the outer serosa and muscularis to seperate, from the inner mucosa and submuucosa Closure (change gloves for closure) - two layer closure; suturing the two layers seperately (serosa and muscularis and mucosa/submucosa) - appositional suture in mucosa/ submucosa as it promotes accurate apposition and rapid mucosal seal. - inverting sutures are appropriate fro the outer layer, as the lumen diameter is large. - reduce adhesions as sutures are turned inwards - use polyglyconate or poliglecaprone

Answer 121

Pass poole Can be used for immediate suction into the stomach and duodenum during surgery to prevent contamination.

Answer 122

Principles of GIT surgery The seven principles of GI surgery 1. Asepsis 2. Gentle tissue handling (debakey forceps, stay sutures). 3. Seperate instruments for clean vrs contaminated portions of the procedure 4. Change gloves for closure 5. Good exposure / exteriorise 6. maintain tissue hydration 7. avoid spilling of contents / pack off with lap sponges and use stay sutures Suturing principles - secure closure - prevent leakage (must test) - serosal apostion minimises adhesions - strength layer is the submucosa - single layer closure for SI to preserve lumen diameter - two layer closure when there is a large lumen diameter (suture like with like whenever possible) - polyglyconate, polyglecaprone Optimal GIT healing depends upon; - blood supply - accurate mucosal apposition - minimal surgical trauma

Answer 123

Gastropexy Permenant adhesion of the stomach to the adjacent body wall. Indication: to prevent GDV and hiatal hernia suture muscle (serosa + muscularis) to muscle 3.0 monofilament The various types; Incisional gastropexy - continous suture joins the stomach to the abdominal wall - ensure tension free Belt loop gastropexy - seromuscular flap is elevated from the pyloric antrum and passed and passed through two parallel incisions on the abdominal wall. - incororates a branch of the gastroepiploic artery Tube gastropexy - indicated for feeding when more rostral disease prevents normal alimentation - placed RHS for post op GDV decompression - mushroom tip catheter - must remain in situ 7-10 days to ensure good adhesion and seal around stoma Circumcostal gastropexy - similar to a belt loop gastropexy, but the loop arise from the lesser curvature and wraps around the 11th or 12th rib at the costochondral junction. - risk rib fracture or pneumothorax Grid approach to gastropexy - endoscopically assisted gastropexy - stomach inflated, and two stay sutures are placed from external pyloric wall through pyloric antrum - an incision is made down to the stomach and then a gastropexy is performed.

Answer 124

Gastric wall incision / suturing Post incision; the gastric wall readily divides into an inner layer (mucos + submucosa) and an outer layer (serosa + muscularis) Suture polyglyconate and poliglecaprone. Inner layer - increadible tough as it needs to withstand the onslaught of whatever is ingested. - submucosa is the holding layer - appositional suture patterin in submucosa as it promotes accurate tissue apposition and rapid healing mucosa. - Gambee, simple interupted Outer layer Inverting sutures are appropriate as the lumen diameter is large. - minimal adhesions due to serosal apposition and minimal exposure of suture. - security against leakage serosal seal - example, Connell, Lambert

Answer 125

Treatment of pyloric outflow obstruction. Various surgical procedures have been described to speed gastric emptying. **Y U Pyloroplasty** - Y shaped incision over the pylorus - tongue of proximal segment is inserted into the stem of the Y resulting in a U shaped suture line and wider pyloric outflow. **Heinke Miculcz pyloromyotomy** - a longitudinal incision from the distal antrum to the duodenum closed transversely Billroth type one and two - indicated when removal of the pylorus is indicated - lumen sizes to be anastomised are grossly different in diameter - involves varying degrees of removal and anastomosis with a poor prognosis.

Answer 126

Gastric outflow obstruction Aetiology - young dogs - benign hypertrophy of the pyloric mucosa and musculature - retards gastric emptying - causes chronic intermittent vomiting and pain - the CS and signalment are suggestive of a diagnoses Older dogs - usually caused by tumours of the pyloric area, pancreas or biliary tract

Answer 127

**Gastric obstruction** Clinical signs - vomiting - abdominal distension - abdominal pain - electrolyte and acid base abnormalities Electrolyte changes seen with gastric obstruction - hypochloraemia - metabolic alkalosis - hypokalamia sequested and vomiting - hyponatraemia sequested and vomiting - hyperlactatemia >2.4mmol/L (peritonitis, GDV)

Answer 128

GDV Gastric dilation and volvulus Aetiology - increased thoracic depth ratio - large dogs underweight + rapid eating predisposes - exercise immediately following a meal - once daily feeds - dry kibble Pathology Stomach fills with gas and then becomes rotated, potentially blocking the entrance and excit - most present with a tympanic membrane - gastric dilation - gastric volvulus (enlarged stomach and ischaemia). - can compress the caudal vena cava causing vascular compromise and shock - pressure in stomach causing ischaemia of the gastric wall - may cause a splenic infarction.

Answer 129

Clinical signs gastric dilation and volvulus - abdominal distension with tympany - unproductive vomiting or retching - compensatory shock (MM increased HR and weak pulses - splenomegaly - decompensatory shock reduced HR pale MM and decreased HR - depressed lethargic

Answer 130

GDV gastric dilation and volvulus Medical emergency requiring rapid decompression. Not a surgical emergency - prolonged medical stabilization will not change the outcome. - diagnosis RADS and measure lactate on admission (lactate can indicate perfusion) Medical management - shock therapy IV and fluids - decompress the stomach (Trocarisation RHS) - stomach tube sitting dog upright - GA and stomach tube Surgical management once stable - rapid induction to protect the airway - midline laparotomy - decompress stomach - derotate the stomach "left and left" - pylorus travels ventrally and then dorsally along the left abdominal wall - the stomach will be covered with omentum rotation 90-360 degrees Assess viability of gastric wall and spleen - allow adequate time for perfusion of stomach and spleen - de rotate and watch - the greater curvature is the area most affected by a GDV - remove necrotic devitalised tissue. Gastropexy (incisional) to prevent recurrance in the future. + lavage prior to closure - mortality 10-20%

Answer 131

The four-Ps of viability 1. Perfusion - lactate - can incise the seromuscular layer and assess for bleeding 2. Purple - serosal surface colur 3. Peristalsis 4. Palpation - a devitalsied stomach wall will palpate as very thin

Answer 132

Procedure for an incisonal gastropexy An incision is made in the stomach parallel to the abdominal wall (muscularis + serosa only) + a second incision through the transverse abdominis - continuous suture 2-0 monofilament absorbable suture - 4-5cm incision - continuous suture - ensure tension free through positioning of the stomach. (if needed move the stomach around until it sits comftably without tension.)

Answer 133

Hiatal hernia Elements of the abdominal cavity (usually stomach) herniate into the mediastinum through the oesophageal hiatus. Pathology Type one; Sliding hernia most common - cranial movement of gastroeohageal junction - gastrooesophageal region = where the stomach meets the oesophagus. - congenital young animals (bulldog), 2-4months - can also be acquired due to a traumatic event - no demonstratable low oesophageal sphincter (just created by the physical properties of surrounding structures) Type two - portion of stomach moves into the caudal thorax through the hiatus adjacent to the oesophagus Type three - gastrooesophageal intussception

Answer 134

Sliding hiatal hernia type one most common Diagnosis - plain radiographs or positive contrast oesophagram - fluroscopy for dynamic sliding hernias Treatment Address the underlying air way disease first. - second treat the sliding hernia - oesophagopexy - phrenoplasty - left sided gastropexy

Answer 135

Hiatal hernia Clinical signs - regurgitataion, hypersalivation, vomiting - dysphagia - respiratory distress - anorexia and weight loss - congenitally usually begins at 2-4 months - may have secondary changes such aspiration pneumonia Common in french bull dogs and bull dogs (Brachy) type one sliding hernia. - due to negative intrathoracic pressure - risk of aspiration and worsening of respirtory signs

Answer 136

Anatomy of the small intestine Duodenum - short and relatively fixed Jejunum - ventrocaudal Ileum - terminal portion of small intestine Points of fixture - duodenal colic ligament - root of the mesentary Blood supply Nearly the entire vascular supply is through the cranial mesentary artery - arises beneath L1 Histological layers Mucosa Submucosa - strength holding layer Muscularis - circular and longitudinal Serosa

Answer 137

The fundamentals of small intestinal surgery. Presurgical considerations - Cut early, perform surgery once Dx confirmed (less complex and earlier discharge wit earlier surgery <6hrs) - antibiotic prophylaxis (gram +ve and gram -ve bacteria) controversial / first generation cephalosporin Goals of SI resection and anastomosis **1. Must maintain lumen diameter** - single layer closure - appositional sutures **2. Aim for end to end anastomosis** - various techniques to match lumen diameters - angled cuts **3. Choose site of resection to maximise blood supply to healing edges** - angled cuts - ensure mesenteric artery is close - place ligatures close to blood vessel - (do not cut the blood vessel). **4. Prevent abdominal contamination** - milk intestine away from transection site - exteriorise and pack with moist lapartomy sponges - Carmalt forceps to occlude the necrosed section of intestine - Doyen clamps to occlude the lumen diameter only. **5. omental patching or serosal tacking 6. Pressure testing** Upon resection expect the mucosa to roll out eversion. - ensure needle penetrates all layers for security but attempt to minimise the size of the mucosal bite. (rolled out mucosa may require resection). Post surgical considerations - feed upon recovery - beware vomiting post surgery suggest ileus or dehiscence - can consider tube feeding to rest ailimentary segment

Answer 138

Principles of healing in the small intestine. - secondary healing / impossible to obtain true opposition - most important phase fibrinolysis 3-4 days post op ** Lag phase 0-4 days** Characterised by local inflammation, starts immediately and lasts about four days. - fibrin clot formation - inflammation - epithelial mucosal migration - most dehiscence occurs during this phase - this phase may be prolonged through inflammation or infection - sutures provide the majority of strength during this phase. - end of this phase fibrinolysis **The proliferative phase 3-14 days** The wound strength approaches that of normal bowel - increase in collagen production from fibroblasts during this period - rapid increase in wound strength parallels the increase in collagen levels. ** The maturation phase days 10-180** At the begining of this phase wound has reached normal strength of the bowel - collagen cross linking results in a slow increase in wound strength.

Answer 139

Suture for the small intestine 1. Suture pattern sutures generally placed 2-4mm apart + small bite - continuous modified gambee = less eversion than simple interupted procedures + instrument contact with tissue - single layer, to avoid decrease in the size of the lumenal diameter 2. Place a stay suture at each end - stay suture acts to prevent luminal constriction or purse string effect - at each end tie the continuous sutures to stay sutures 3. Avoid tension - decreases perfusion and predisposes the wound to intestinal breakdown - purse string effect 4.. Suture type - monofilament synthetic absorbable (consider triclosan (antibacterial type suture) 5.. Taper or reverse taper needle - easier passage through the dense submucosa layer and reduce tearing of the serosa 6. Appositional is the technique of choice - accurate apposition of serosa - inevitable results in a small amount of eversion / true apposition is unlikly

Answer 140

Adjunctive therapy for small intestinal anastomosis Omentum Omental tacking to assist with healing by; - adding blood supply - increase lymphatic drainage (macrophages and immune functions) - attracted to sites of inflammation - can be exteriosied from the abdomen - helps to seal gastrointestinal lesions Serosal patching - a healthy loop of bowel is sutured over the damaged section - additional strength

Answer 141

``` Enteromtomy = incision into the intestine enterotomy = is removal of a segment of intestine 1. Maintain lumen diameter - stay sutures - single layer of sutures - appositional sutures 2. Aim for anastomosis - vary angles of incision to match the lumen diameter width 3. Choose site of resection to maximise blood supply - close to mesenteric artery 4. Prevent addominal contamination - pack with lap sponges - stay sutures - milk intestine away from the site of incision - Doyen clamps and Carmalt clamps

Answer 142

Small intestinal obstruction Cause - foreign body = dogs classically corn cob - linear foreign body is far more common in cats (often causing a partial obstruction) - assess material around the base of tongue - neoplasia - stricture / adhesion - intussusception - strangulation (eg inguinal hernia) The consequences of small intestinal obstruction pathophysiology - fluid continues to be excreted proximally to obstruction - malabsorption of water and solute - fluid, electrolyte and acid base disturbance - pressure may cause thining of intestinal wall and translocation of luminal bacteria Proximal obstruction - vomiting of HCL, Na+ and K+ leads to hypochloraemic metabolic alkalosis Distal obstruction - loss of intestinal alkaline fluid - metabolic acidosis

Answer 143

Small intestinal obstruction **Clinical signs** CS vary significantly with the location, material, duration and severity of obstruction. -vomiting, anorexia and depression abdominal pain possible diarrhea - proximal obstruction causes frequent profuse vomiting, while a distal obstruction causes less profuse sporadic vomiting - icterus (EHBDO) **Diagnoses** Radiographs - different populations of small intestine large and small - dogs 2x the height (thinnest part) of L5 in the lateral view - cats L2 x 3 - 30% of cases may not have radiographic signs Ultrasound 97% of cases definitive result Exploratory laparotomy - diagnostic step

Answer 144

Prognosis following surgery on the small intestine ? Overall dehiscence 6.6% Mortality with peritonitis = 50% Should always quote dehiscence rates to owners before surgery.

Answer 145

Preventing contamination during small intestinal anastomosis requires the use of; Carmalt forceps - apply tightly to crush the tissue - function to occlude the ends of damaged tissue that will be removed, to prevent leakage of contents - line of resection is on viable side of this clamp Doyen forceps - be very gentle - apply tightly function to occlude the bowel lumen only - prevent spillage of ingesta - must not damage this tissue as it is not removed - is available assistant fingers are a gentler approach

Answer 146

Staplers and their use in anastomosis Types of staplers - GIT gastronintestinal stapler - Thoracoabdominal stapler Benefits of using a stapler in anastomosis surgery - decresaed surgical manipulation - shorter surgical time - preservation of vascular supply - superior initial strength - consistant spatial arrangement - simultaneous firing of all staples under identical tension - easy anastomosis of bowel ends with luminal disparity Disadvanatges of surgical stapler use - cost - large size of GIA, not always suitable in small sized patients (may used endoscopic stapler)

Answer 147

Large intestine **Anatomy of the large intestine ** - ascending colon, transverse colon and descending colon - composed of four layers; mucosa, submocosa, muscularis and serosa. **The three main functions of the large intestine** 1. Storage of faecal material 2. Essential microbial system - - the large intestine has a higher bacterial load then the small intestine. 3. Maintaining fluid and elctrolyte balance - the colonic muscosa is reasonable for reabsorption of wtaer Na+, CL- short chain FAs - additionally secretion of K+, HCO3_ and mucous.

Answer 148

Large intestinal bllod supply and its relevance to surgery **Large intestine** Cranial mesenteric; middle right and ileocolic - the ascending and transverse colon Caudal mesenteric; cranial rectal and left colic - supplys the descending colon - reduced branching of the blood supply in the descending colon, makes surgery more risky - For example transection of the caudal mesenteric artery could cause icshaemia to a large portion of the colon. - reduced collateral circulation Surgical considerations - individual ligation of the individual vasa recta + left colic artery preferred over occlusion of the major vessels - greater preservation of blood supply

Answer 149

**Diagnostic options for the Large intestine** Most clinical signs of the large intestine relate to - inflammation or inflammation - surgery is indicated to relieve obstruction, biopsy or remove lesions causing irritation/ bleeding. **Always do a rectal exam** - unless the dog has no bum or you have no finger Radiography - size and position of the caecum and colon - pressence of extraluminal masses - stenosis - positive contrast is useful to assess colon size and luminal or intraluminal lesions. Ultrasound - gas and faeces can make UT challenging - Intraluminal lesions, intussuseption or masses - assess sublumber and iliac lymp node - US guided biopsies Endoscopy (gold standard) - allows for biopsy - entire length of LI can be examined with a flexible endoscope CT and MRI - CT pneumocolongraphy

Answer 150

Large intestinal surgery The large intestine has a higher bacterial load compared to the small intestine. Prophylaxis; **Antibiotics** - Gram -ves and anerobes - second generation cephalosporin / ampicillin - first generation cephalosporin and gentamycin - Metronidazole for anerobes - reccomend to start prophylaxis 24 hours preop ** Diet** - high residue low fat - avoid altering the normal diet too much as - aim for well formed stools - easier to keep from surgical site - avoid liquid faeces difficult to maintain clean contaminated surgical field. Most large intestinal procedures are elective, allowing for time to prepare the patient.

Answer 151

**Subtotal colectomy** - a distal transection of the bowel at the transection of the rectum and colon and ileocaecal valve is preserved. **Total colectomy** - a distal transection of the bowel at the transection of the rectum and colon and the ileocaecal valve is not preserved. **Surgical correct Feline idiopathic megacolon Subtotal colectomy ** - cat recurrent constipation and obstipation - colonic receptor do not respond normally causing decreased strength of muscle contraction **- RADS **colin width compared to length of L2 x 1.5 **Subtotal colectomy recommended ** - patients refractory to medical treatment. - resection of the entire colon, except two cm cranial to the pubis to allow anastomosis. - whole colon is affected histologically and recurrance is higher if less is removed - Leaving the ileocaecal valve if possible, studies indicate motions are firmer (reduced watery diarrhea)

Answer 152

**There is poorer healing in the LI compared to the SI** 1. reduced collateral circulation 2. higher intraluminal pressures / mechanical stress on the suture line with the passage of faeces -3. higher bacterial load - often more difficult to access and visualise - the danger period for leakage is 3-4 days post op as collagen lysis exceeds collagen production upto this point. - normal motility is not restored for 8 weeks post anastomosis, same time as restoration of cholinergic fibres across the anastomosis. ** What can we do as surgeons** - good mechanical cleansing of bowel preop - appropriate antimicrobial usage - ligate blood vessels at the vasa recta of the left colic and caudal mesenteric arteries - atraumatic surgical technique - choose a suture pattern that dose not strangulate or disturb blood flow to healing tissues - use of omentum / serosa patches - stappling devices (linear intestinal stappler / ened to end anastomosis stapler)

Answer 153

Surgical approach to the large intestine **Laparotomy** - only provides access to lesions cranial to the pubic brim - approach of choice for lesions accessable from the abdomen **Rectal mucosal eversion** - can be used fr mucosal lesions within 3-4 cm of the anus **Trancutaneous rectal pull through** - available for full thickness lesions in caudal 6cm of rectum **Pubic resection - pubic symphysiomtomy** - lesions with the pelvic cavity - must preserve the cranial rectal artery as it is the important blood supply to the intrapelvic rectum

Answer 154

Faecal continence depends on the anal sphincter and terinal rectum - last 3-5 cm inside the anus

Answer 155

Differential list for the large intstine, rectum and perineum ? **Large bowel** Functional obstruction / mechanical obstruction - dietary indiscretion; bones cooked - idiopathic megacolon in cats - prostatic disease - perineal hernia - pelvic fracture - neoplasia - stricture or abscess Anus and perineum - rectal prolpase (constipation) - prolapsed intusssusception - Anal sacculitis / abscess - perianal tumour, adenoma, adenocarcinoma and adenomatous polyp

Answer 156

The principles of anal sac surgery Anal sacculitis - bacteria proliferate in anal sac secretions - causing pain and scooting - eruption as an abscess onto the perineal skin Treatment options Irritated / infected anal sacs; - Flush and pack with local antibiotics Anal sac abscessation; - GA, flush and debride, treat as an open abscess - anal sac excision Anal sac excision - respect the anal sphincter - poor Sx can lead to post op faecal incontinence - Delay surgery until inflammatory disease is controlled - Open vrs closed technique - little difference in surgical outcome between open vrs closed excision - most important remove all the excretory epithelium - meticulous careful surgery - a greater rsik of incontenance with bilateral Sx - must protect and preseve the anal sphincter fibres and branches of the pudendal nerve (S2-S4). Complications - incontinance - removal of anal sphincter - infection - stricture formation caused be excessive tension

Answer 157

**Rectal prolapse Pathophysiology** - Partial anal prolapse - only mucosa protrudes through the anus - Complete rectal prolapse - full thickness rectum protrudes as a single mass - Anal prolapses (especially older animal) is usually a result of an underlying disease / predisposing factor causing straining (coilitis, prostatic disease, parasites, dystocia) **Treatment of a rectal prolapse** Urgent treatment required to prevent irreversible injury to the exposed bowel. - incarceration or strnagulation - Test bowels for viability, 4P (purple, perstalsis, perfusion and palpation) additionally response to osmotic challange In case of viable tissue - lubricate - reduce prolapse size with a hypertonic solution (NACL/sugar) - replace completely (completely reverse telescoping) - place a purse string suture In the case of unviable tissue - resect prolapsed tissue - anastomose in sections In the case of recuurance (recurrent viable prolapse) - laparotomy - reduce by traction from within the abdomen - check for underlying disease - colopexy of descending colon to the left internal surface of the abdomen.

Answer 158

Anal sac anatomy Location - 4oclock and 8oclock between the external anal sphincter and internal anal sphincter Surgical significance - high risk of incontenance post surgery - must preserve / protect the anal sphincter fibres and branches of the pudendal nerve (S2-S4).

Answer 159

How to distinguish between a rectal intussusception and a rectal prolpase They both appear the same visually, must be differentiated by passing a probe between the prolpase and rectal wall. - this is only possible in the case of an intussception.

Answer 160

Management pf neoplastic disorders affecting the perineum ( A biopsy is warranted) ** Perianal adenoma - excise and castration** - mostly entire males, testosterone dependant tumour - may ulcerate and bleed - not nasty but may progress - usually castration is curative (small and not ulcerated) - if ulcerated or rapidly grwoing wait 4-6 weeks when resction and castration will be easier - mucosal eversion include muscularis and submucosa ** Perianal adenocarcinoma - hyper Ca, nasty** - uncommon <20% grow fast and mestastasize - independant of testosterone - spread circumferentially or radially - obstruction occurs due to disruption of peristalsis and luminal compromise - the infiltrative form invades the rectal wall leading to fibrosis and stricture formation - poorer prognosis - surgical approach based on location and size - requires margins The key point we can not distinguish adenocarcinoma and adenoma visually always biopsy.

Answer 161

**AGASACA** (anal sac neoplasia in dogs) Apocrine galand anal sac adenocarcinoma - highly malignant tumour with high metastatic potential to regional lymph nodes - consider lymp node mapping - more common in older female dogs - hyper Ca with hypophosphataemia - due to a parathyroid like hormone secreted by the tumour Treatment - remove the primary mass - remove the contralateral gland - remove any enlarged abdominal lymph nodes - Adjunctive therapy rdaiation, chemotherapy - if recurrance repeat lymph node removal is advantageous Prognosis -2 years longer with chemo - do not treat if mets are present

Answer 162

Liver functions ** The liver has many crucial functions** 1. synthesis and clearance of plasma proteins 2. carbohydrate and lipid metabolism (always check glucose levels) 3. synthesis of coagulation factors and anticoagulanst 4. modifies immune function 5. GI health through bile and hormones ( emulsifies fat, biliribin, cholesterol, water bicarb) 6. Storage 7. Clearnace organ ** Liver disease and pre-operative considerations** 1. Haemorrhage - coagulation profile, blood typing, cross matching - pre treatment with vitamin K 2. Anaesthesia - aviod liver metabolised drugs where possible, consider ventilation for large massess due to diaphragm compression 3. Hypoglycaemia 4. Hypoalbuminaemia - fluid leaks from vessels to tissue, be prepared to provide plasma 5. Bacteria (antibiotics) - there are bacteria normally located withn the liver parenchyma removed by liver Kupffer cells - translocation of bacteria

Answer 163

Anatomy of the liver Know the lobes of the liver **Left lobes** - left lateral - left medial - caudate lobe **Right lobes** - right lateral - right medial - quadrate lobe Blood supply - each lobe of the liver is supplied by the hepatic artery and portal vein - drainage of the liver occurs through the vena cava

Answer 164

The liver is a parenchymal organ The liver capsule is much tougher than liver parenchyma + blood vessels and larger biliary ducts are much tougher than liver parenchyma. (never attempt to suture liver parenchyma friable tissue) Technique - anchor sutures in capsule to compress tissue (can use fat to help support suture if capsule fragile). - ligate ducts and vessels after blunt dissection of parenchyma - use flat hands to manipulate the liver - use large flap compression instruments to clamp liver, remember the liver is highly vascular and will always bleed

Answer 165

Cat vrs dog biliary tract anatomy The gall bladder reservoir is joined to the main biliary tree by the cystic duct - each liver lobe has its own hepatic duct - the cystic duct and hepatic ducts join to form the common bile duct which empties into the duodenum through the **major duodenal papilla** Cat In the cat the common bile duct and pancreatic duct join and subsequently enter the duodenal papilla as a common duct. Dogs In the dog the pancreatic duct empties immediately adjacent to the opening of the bile duct at the major duodenal papilla.

Answer 166

**Biopsy techniques of the liver** (to remove tumours excisional biopsy, or to take samples for histopath incisional biopsy). - diseased liver is much more friable, addition of fat can provide support. **1. FNA Fine needle aspirate** - can be performed percutaneously or at surgery. ** 2. Guillotine biopsy** - for smaller sections near pointed ends of the lobes - multiple or single sutures are placed through the liver and pulled through the parenchyma encircling vessels and bile ducts. - absorbable suture - the isolated tissue is then biopsied. **3. Suture compression wedge** - similar to the guilatine technique, useful for sites along the edges of lobes - V shaped suture lines isolate tissue to be removed - sutures lightly compress liver without cutting through - excise V shaped tissue with a scalpel or scissors **4. Tissue fracture technique** - best technique for large biopsies - blunt fracture of parenchyma with the scalpel handle or other similar instrument (fingers) - identify bile ducts and vessels left intact, clamp and ligate - transect distal to ligatures **5. Biopsy punch technique** - Disposable skin biopsy punch 2-6mm, pressed into the liver tissue - plug of tissue ready for gentle removal br fracturing base of plug using a sideways rocking motion - insert gelatin sponge plug for haemostasis - cover site with omentum **6. Ligasure** - seal of vessels and parencyma - 3mm of necrosis

Answer 167

**Portal systemic shunt** An abnormal connection between the portal vein and systemic circulation. - blood from the portal vein (intestines) bypasses the liver - two types congenital or acquired - can be intrahepatic or extraheptaic - congenital extraheptic are the easiest to treat **Clinical signs** The clinical signs result from the inability of the liver to remove waste products (neurological). - present 1 month to 2 years of age - small stature runt, mental dullness, lethargy - neurological signs = head pressing, staring at walls or random barking - cats pytalism - lower unrinary tract signs pollakiuria, polydipsia - anaesthetic intolerance - GI issues **Diagnoses** - non regenerative anemia and microcytosis - low albumin, BUN and glucose - mild to moderate increase in liver enzymes - amonium biurate calculi - liver function test = bile acid tolerance test. **Imaging** - radiographs microhepatica - ultrasound may see aberrant vessels - CT angiography (glod standard) - Scintigraphy

Answer 168

**Treatment Portal systemic shunt** **Medical management: required prior to surgery** - IVFT and electrolyte support - glucose in young pups - Enemas; warm water and lactulose(promotes acidification of colonic contents / entrapment of luminal ammonia + reduce colonial bacterial numbers) - Phenobarbitone anticonvulsent therapy - antibiotics metronidazole - nutritional managemnt protein restrictive diet (Soy) - protein pump inhibitors omeprazole - SAMe, vitamin E **Surgical treatment PSS** Gradual occlusion is preferred of single congenital PSS - multiple acquired PSS should be managed medically - sudden oclussion causes backwards pressure (microheptica reduced liver size) Ameroid constrictor - swells when in contact with water to slowly occlude the vessel Cellophane - causes an inflammatory response and granulation tissue which acts to slowly occlude the vessel.

Answer 169

**Biliary tract obstruction** (bile acts to emulsify fat - absorbed by the large intestine transported by the portal vein back to the liver). **Pathology** - ascending infection into gall bladder cholestasis - pancreatic and pyloric neoplasia - primary neoplasia of the biliary tract - obstruction from outside the duct (EHBO) pancreatitis, cholangitis - leakage of bile may remain contained as a mucocoele **Surgical corrective techniques** Start by identifying the site of leakage or obstruction. 1. Cholecystectomy 2. Cholecystoduodenostomy 3. Liver lobectomy

Answer 170

Definitions **Cholecystoduodenostomy** - suture over tube and reimplant into duodenum - diversion procedure for biliary tract obstruction **Choledochal stenting** - stent placed in the common bile duct - treatment for non neoplastic disease - better prognosis in dogs than cats **Cholecystectomy** - removal of the gall bladder

Surgery GIT Flashcards

(197 cards)