Small Animal Surgery - Residency (my own cards) Flashcards

Question

What is a delayed union?

Answer 1

Fractures that heal more slowly than anticipated. Most long bones have signs of bone bridging by week 12 - but with delayed union this might not be the case. Delayed unions maintain evidence of activity on sequential radiographs - and boen union is anticipated but not ensured.

Answer 2

As long as implants are sound; continued strict rest should suffice. Cancellous bone autografts may be addedd to speed healing before implant failure occurs. Loose or migrating implants should be explanted.

Answer 3

Factors contributing to delayed union: - systemic status of patient (ie malnutrition or aneamia) - nature of original trauma / soft tissue disruption - local host post-injury response (ie inadequate cellular response for bone healing) - infection - fracture management (ie poor decision making, large fracture gaps [ gaps >1.5x width of bone], unstable implants, implants that are too rigid, radiation therapy) - pharmacological (eg steroids, NSAIDs)

Answer 4

VIABLE NONUNION Characterised by variable degress of proliferative bone reaction - with interposed cartillage and fibous tissue. Three subtypes: - **Hypetrophic** ('elephant foot') - **Slightly hypertrophic** ('horse hoof') - **Oligotrophic** Viable non-unions will progress to union with rigid stabilisation while oligotrophic nonunion will benefit from opening medullary caity and bone grafting

Answer 5

NON-VIABLE NONUNION Poor bloody supply or none at all. Four subtypes: - **Dystrophic** - **Necrotic** - **Defect** = >1x width of bone defect - **Atrophic** Non-viable nonunions benefit from debridement of necrotic soft tissue and bone, opening medullary cavity at fracture ends, rigid fixation and cancellous bone grafting

Answer 6

A Fracture that has healed in an abnormal position causing various degrees of functional impairment of the limb Usually results from untreated or improperly treatede fractures functional impairments seen: - limb shortening (usually if >30%) - angulation or rotation - uneven weight distribution over a jont surface - restriciton of adjacent joint movement

Answer 7

1. Over-riding 2. Angular 3. Rotational 4. Intra-articular - where there is malalignmenet of articular surfaces

Answer 8

1. **Haematogenous** - rare in cats & dogs , occuring most commonly at the metaphyses of long bones in young animals. Bone biopsy for histo and culture & senstivity. Radiographic evidence may be absent for up to 7 days. 2. **Acute** - complication of open frcatures or open reduction of closed fractures, but occasionally due to bite wounds. Clinical signs occur within 5-7 days after repair. Most often culture = gram-positives like staph (most common), or strep. Occasinally G-ves like E.coli, proteus, klebsiella, pseudomona (enterobactericiae) are cultured. Surgical prep of skina nd FNA of fractrue site will help aide antibiotic therapy. Prolonged antibiotic course (6wks) after which a sedon culture should be performed 3-5days after antibiotic course finished. 3. **Chronic** - bacteria have cell membrane receptors that bind to fibronectin on implants. Bacteria also produce a glycocalyx which shields them from body's immune system. This biofilm can also induce some bacteria to transform into more virulent forms. Common clniical signs include chronic draining tract, lameness and disuse muscle atrophy. Aggresive intervention required which may include removal of loose implants, additional rigid fixation and improving the biology by addition of cancellous bone graft. All implants will eventually need to be removed to achieve complete resolution of infection. ## Footnote Rigid fixation is key - clnical union will usually be achieved despite infection, as long as there is absolute stability.

Answer 9

DOGS: - Adenocarcinoma (70-80% of gastric neoplasia) - Leiomyosarcoma - Other malignant tumours: lymphosarcoma, mast cell tumour, extramedullary plasmacytoma - leiomyoma = most common benign tumour CATS: - lymphosarcoma is the most common gastric tumour type ## Footnote Gastric adenocarcionmas behave aggreisvely and frequently metastasis to regional lymph nodes, liver and lung. Thorough pre-op staging is indicated. Surgical excision (Bill roth I or II) is most effective treatment, although majority of patients do not survive longer than 6 months

Answer 10

longitudinal incision is made along ventral aspect of pylorus, through serosal layer, muscularis and submucosal layer - leaving only the mucosal layer bulging out of the incision at the end of the procedure.

Answer 11

Similairly located incision to the Fredet-Ramstedt procedure - longitudinal incision of ventral pylrus is made, but full thickness incision incision. Stay sutures used to draw the longitudinal incision into a transveres one. Single layer closure then performed.

Answer 12

Similair again to the Heineke-Mikulicz procedure, but the pyloric incision is then extended into a 'V' shaped incision at the cranial margin of the incision extending into the antrum of the stomach. This is the closed as per standard single layer closure with the antrum flap advanced into the pylorus - once closed effectively widening the lumen. ## Footnote This widens the pylorus significantly, with a risk of entero-gastric reflux possibly occuring

Answer 13

Pyloric stenosis can be either congenital (typically seen in brachycephalic dogs), or acquired. Both terms describe obstruction f the pyuloric canal caused by hypertrophy of the pyloric smooth muscle, mucosal hyperplasia or both.

Answer 14

- Increasing adult body size and age - Breed (Great dane, Weimeraner, St Bernard, Gordon Setter & Irish Setter) - Thoracic conformation (deep chested animals) - once daily feeding - Gender (male) - Feeding a single food type - Recent kenneling or car ride - Nervous temperament (repeatedly been shown to be highly associated) - eating rapidly (associated with temperament somewhat) - If oil or fat was one of the primary ingredients being fed - Post-prandial activity - If a first relative has had a GDV (significant association) - Being fed from elevated bowl These factors may assist in recommendation regarding prophylactic gastropexy Post-splenectomy? controversial - and little evidence that supports the need to routinely perform pexy after splenectomy - unless there are significant other risk factors present for GDV

Answer 15

- Restlessness - pain - abdominal tympany - wretching - salivation Single RIGHT lateral abdo radiograph. Distinctive 'double-bubble', 'smurf-hat' or 'biceps' appearance of stomach caused by Dorsal displacement of the pylorus

Answer 16

Dilatation only gives rise to volvulus if the pylorus is already malpositioned. Meaning not all dilatations will result in a volvulus. Gas analysis of the stomach of GDV dogs has shown that the gas is predominantly a result of aerophagia rathert than gastric fermentation Majority of cases the stomach rotates in a **clockwise** direction as viewed cranially with the dog in dorsal recumbency - with the pylorus moving ventrally and cranially to the rest of the stgomach. To rectify the volvulus once decompressed the pylorus located on the dog's left side now, is grasped and drawn ventrally (toward the surgeon) back into the normal anatomical positione, with the rest fo the stomach (obscured by omentum usually) pushed dorsally and displaced from the aniaml's right, back to its normal position on the dog's left. [(see video)](https://www.youtube.com/watch?v=JaAN-6FrPTM)

Answer 17

Gastric dilatation **→** compression of portal vein and caudal vena cava **→** congestion of blood in abdominal organs and caudal skeletal vascular beds **→** tissue hypoxia and lactic acidosis **→** Decreased venous return **→** decreased cardiac output **→** poor tissue perfusion and arterial hypotension **→** Eventual hypoxia in all organ systems **→** with the heart suffering focal myocardial ischaemia **→** cardiac arrhythmias seen with this condition. Acid/base and electrolyte changes, autonomic imbalances or myocardial depressant factor produced by the ischaemic pancreas spleen and other organs, may also contribute to arrhythmias ** STOMACH:** intramural pressre and decreased venous drainage causes oedematous mucosa, with localised hypoxia, haemorrhage and eventually ischaemic necrosis. Short gastric artery branches of the splenic artery disruption/avulsion may also result from severe gastric , with haemorrhage fromt ehse vessels presenting as an additional risk. Necrosis of the stomach at the fundic region may also develop as a result which may lead to subsequent perforation, sepsis and possibly lead to shock. **Plasma lactate >6mmol/L** was considered reasonably sensitive but not specific indicator of gastric necrosis (de Papp et al 1999). In this study; 66% of dogs with gastric necrosis survived, compared with 98% without **SPLEEN:** Splenic enlargement from engorgement from reduced venocu drainage may also occur. **SMALL INTESTINE: **Loss of mucosal integrity, which may lead to absorption of bacteria and endotoxins. This may lead to endotoxaemia and dissminated intravascular coagulation. **Additional negative prognostic indicators: ** - clinical signs >6hrs - systemic hypotension (at any time during treatment - peritonitis - ECG abnormalities - sepsis - DIC - needing to perform a splenectom or partial gastrectomy are not negative risk factors but are associated with risk of peritonitis

Answer 18

Non-inflammatory. aseptic necrosis of the femoral head - occuring in young patients prior to capital physeal closure. This disease results in collapse of the femoral epiphysis because of an interruption of blood flow. Cause for loss of blood flow is unknown but several theories include; - hormonal influence - hereditary factors (links to an autosomal recessive gene) - anatomic conformation - intracapsular pressure - infarction of the femoral head Vascular supply to epiphysis in young dogs comes solely from epiphyseal vessels; metaphyseal vessels do not cross the physsi to contribute to femoral head vascularity. Epiphyseal vessels crouse extraosseously along surface of the femoral neck - cross the growth plate and penetrate bone to supply nourishment to femoral epiphysis. Synovitis or sustained abnormal limb position can collapse delicate veins and inhibti blood flow. Bone substance consequently is weakened and during repair phase the weakened epiphysis undergoes collapse during normal weight bearing. Consequently incongruence between femoral head and acetabulum forms resulting in DJD. Fragmentation or the femoral epiphysis and osteoarthrosis cause pain and resulting lameness

Answer 19

SIGNALMENT - small-breed dogs (<10kg) - peak incidence of onset 6-7months (range of 3-13months) - equal gender predisposition - occurs bilaterally in 10-20% of cases HISTORY - usually present with slow onset weight bearing lameness that worsens over 6- to 8-week period - lameness progressess to non-weight bearing eventually - some clients report acute osnet lameness - this may be in association with epiphyseal collapse event & initialy mild lameness may have been missed by them - other signs include irritability, hyporrhexia, chewing at area over hip PHYSICAL EXAM FINDINGS - pain on extension of hip / manipulation of joint - muscle atrophy - crepitus (in advanced disease) DIAGNOSTIC IMAGING FINDINGS - Radiographs show deformity of the femoral head, shortening and/or lysis of the femoral neck - - the femoral head may appear moth-eaten and misshapen - A CT scan may become necessar to identify lysis or cavitation witin an affected feoral head that maintains a relatively normal shape TREATMENT - Non-painful condition in early phases prior to epiphyseal collapse, with diagnosis often made only after collapse and fragmentation have resulted in joint incongruity and DJD - medical management (anti-inflammatories, and leash-limited or non-weight bearing excercise such as swimming, may provide pain relief in small percentage (with weight-bearing limintation attempting to prevent epiphyseal collapse), however most require surgery - Surgery: THR or FHNE

Answer 20

CT reflex is tested by pinching the dorsal skin adjacent to the dorsal spinous processes, and tested on btoh left and right sides. Pinching of the skin using a haemostat is performed starting from the cranial margins of the ilium, and moving cranially one vertebral space at a time. **Sensory nerve** = *dorsal nerve roots* (usually traversing approx 2 vertebrae cranial to where the pinch is being sensed) **Motor nerve** = *lateral thoracic nerve* - eminating from *C8-T2* spinal segments

Answer 21

*In regards to intranasal massess, which type of 'faced' animals (ie brahcycephalic or dolichocephalic breeds) is more predisposed to nasal tumours?* **Dolichocephalic breeds** are particularly susceptible to tumours of the nasal cavity, as are older male dogs *What is the median age of onset for nasal tumours*? **Median age** of dogs presenting with clinical signs is **10yrs** old *What sex is more diagnosed with nasal tumours?* **Males** are TWICE as likley to present with nasal tumour cf. females *If a young animal presents with a nasal mass, what is the most likely diagnosis?* **Aspergillus** is mroe prevalent in younger animals cf. older animal

Answer 22

Aim to address two factors: 1. shock therapy 2. gastric decompression SHOCK THERAPY - Large bore IVC - most ideally placed in jugular vein - large volume fluid resusscitation - up to 80mL/kg in first hour and then maintained at 10-20ml/kg/hr - correction of acid/base imbalances best done on blood gas analsis as both acidosis and alkalosis may occur, however most commonly see mild metabolic acidosis and hypokalaemia - Alkalosis can result from outpouring of GIT fluids (H+) into the dilated stomach which thus may counteract the metabolic acidosis GASTRIC DECOMPRESSION - best done by stomach tubing - lubricate the tube end and ensure you don't roughly insert into stomach which may perforate thinned/necrotic gastric walls - if this is unsuccesful, gastrocentesis using a long wide-bore needle, catheter or trocar can be fone - inserted into left flank - percussion of abdominal wall is done to prevent inadvertent penetration of malpositioned engorged spleen - Gastrocentesis aims to remove gas only within the lumen, with small reduction in gas distension, signficant decrease in wall pressure and imporvement in perfusion SURGICAL - decompression and surgical derotation is subsequently indicated - splenectomy and gastropexy are subsequently performed POST-OPERATIVE CONSIDERATIONS - cardiac arrhythmias commonly occur during anaesthesia and for 48-2hours post-op - ECG monitoring during this time is indicated - Paroxysmal ventricular depolarisation & ventricular tachycardias are most common - idl arrhytmiasusually don't need intervention - V-tach or VPCs which subsequently negatively effect blood pressure should be treated (typically using lignocaine CRI)

Answer 23

All gastropexy techniques rely on direct contact between gastric muscularis layer and the abdominal musculature beneath the peritoneum to predictably result in strong adhesion between the two layers. Mesothelial cells of the peritoneal lining have capsacity to produce plasminogen activators, which lyse newly formed fibrin polymers, thus incision on both visceral and parietal surfaces is required. i) **Incisional gastropexy (suture gastropexy)** The standard gastropexy performed whereby the pylorus is incised, as is the abdominal wall just caudal to the last rib (transverse abdominus muscle) - and the two sutured together. ii) **Tube gastropexy** An 18-24F foley catheter is forced through a stab incision in abdominal wall just right of ventral midline, and 4 cm caudal to last rib. The tube penetrates the greater omentum and enters the stomach via a stab incision placed in the pyloric antrum. The bulb is inflated using saline and pre-stab incision placed purse string in pyloric antrum is then tightened to create a seal. 3-4 simple interrupted sutures using 2-0 monfilament suture aims to secure the antrum to the abominal wall. The tube is then secured externally using roman sandal suture. This is simlair to a gastric feeding tube, except feeding tubes tend to utilise mushroom tipped catheter. *The tube must remain in place for 7-10 days to allow adhesions to adequately develop* . This is a lesser favoured techinuqe due to the required aftercare and recurrence rate of dilatation and volvulus. iii) **Gastrocolopexy** iv) **Circumcostal gastropexy** Utilises a msucular flap to anchor the sotmach to the last rib. Easy and quick, producing a very strong adhesion, stronger than tube or incisional. It is more difficult to perform and a rib fracture or pneumothorax are possible complications v) **Belt-loop gastropexy** This is a modification of the circumcostal - incision into the abdominal wall (transverse abdominus) is amde which creates a loop of muscle centred 3-4cm caudal to the coastal arch and approx one third from the ventral to dorsal midline. A belt of muscle (a flap) of seromuscularis of the pylorus is created - ideally centered on a branch of the right gastroepiploic artery. This belt of muscle is then passed cranil to caudal, or caudal to cranial (in deep chested dogs usuallyt he latter) and resutured into place on the pylorus using simple interrupted suture. vi) **Laprascopic assisted gastropexy**

Answer 24

- Intestinal adenocarcinoma - leiomyosarcoma - gastrointestinal stromal tumours (GIST) *Leiomyosarcomas and gastrointestinal tumors most commonly effect the caecum*

Answer 25

- Lymphosarcoma is the most common Oher differentials include; - gastrointestinal mast cell tumour - intestinal adenocarcinoma

Answer 26

Types of ESF: 1. Linear ESFs 2. Circular ESFs 3. Free-form ESFs = pins & cold-set epoxy/epoxy putty (knead-it) 4. Hybrid ESFs = combination of linear and circular Linear ESFs are classified by **the number of planes occupied by the frame** and **the number of sides from which the fram protrudes from the bone** - **Unilateral-uniplanar = Type Ia** - **Unilateral-biplanar = Type Ib** - **Bilateral-uniplanar = Type II** (divided into maximal (**Type IIa** and minimal (**Type IIb - aka Type II modified**) types - depending on whether <2 or >2 bars cross pins connect the two longitudinal frame bars) - **Tie-in ESF** - classified on it's own - but typically is done with a single bar and an IM pin - can be thought of as modification of Type Ia in this configuration - **Bilateral-biplanar = Type III**

Answer 27

Type IIb (aka modified Type II, aka minimal Type II)

Answer 28

Type IIa (aka maximal Type II)

Answer 29

**Advantages** - Can be applied in 'closed' manner limiting disruption to soft tissues (true MIPO) - Adaptable, with infinite combination of fram and pin configs - very versatile (using epoxy or tubing/epoxy frames increases adaptability infinitely) - Well suited when reconstruction of fracture is not primary goal - Ideal for open frcatures (this is more debatable as some argue ORIF is still suitable) - Do not involve permanent implants prone to delayed implant infection - Can be combined with other implant techniques as is done with tie-in ESFs - Adjustable post-operatively if alignment is suboptimal in post-op rads - allow fixaiton of uxta-articular fractures where bone stock is less than what is required for plate fixation - Relatively inexpensive hardware - is largely reusable - Can more easily dynamize compared to plate constructs **Disadvantages** - pin tract infections, discharge from pin tracts and septic loosening of pins is common - ESFs are unsuitable for fractures with a high FAS - ie those that are predicted to heal at a slower rate - as the chance of complications is higher the longer the ESF is in-place - ESFs can become entangled/caught on environmental objects - possibly causing further trauma or disruption to healing ('Chip' for example) - Not possible to axially compress fractures and therefore no load sharing is possible

Answer 30

1. Aim for 4 pins per bone fragment (2 pins per fragment as absolute minimum) - increasing the number of pins per fragment reduces the pin-bone interface stress of each pin - but little benefit beyond 4 pins per fragment 2. use the *Far-near-near-far* principle - same as locking plates - thus reducing the working length of the ESF bar 3. The minimum distance between ESF pin and end of bone/fracture line = HALF the bone diameter (similair concept to cerclage wire) 4. Space pins as far from one-another as possible (increases bending stifness of the entire construct) 5. Use threaded pins where possible (have 10x resistance to pull-out as smooth pins), & if using smooth pins - they should be placed at angles >70degree to one another to adequately resist pull-out (see figure below) 6. Pin diameter should be 20-25% bone diameter - with thread diameter (+ve profile pins) should not exceed 30% bone diameter) 7. Reduce pin working length as much as possible - shorter the pin working length the stiffer the construct *Placing the connection bar ~1cm from the skin (finger width) is optimal combination of alowing soft tissue clearance whilst keeping the ESF as stiff as possible*

Answer 31

- Pre-drill before inserting positive-profile pins - Increase pin numbers (up to 4 pins per bone segment) - Increase pin size (up to 25% bone diameter) - Place pins near the joints and near the fractures - Decrease the distance between the bone and the pin/clamp interface - Increase the diameter of the connecting bar or use double bars/augmentation plates - Increase the number and planes of connecting bars - Tie the intramedullary pin into the fixator frame

Answer 32

**Hansen Type I:** The nucleus pulposus undergoes progressive loss of proteoglycans, becoming dehydrated and mineralized (chondroid degeneration). This leads to loss of ability to distribute pressure and causes secondary degeneration and rupture of the annulus fibrosus. This usually culminates in the expelling of nucleus contents towards the dorsally located spinal cord (thinnest part of the annulus) during an episode of mechanical stress. This is know as Intervertebral Disk *Extrusion*. The resulting injury leads to various degrees of contusion and compression. **Hansen Type II: ** Chronic chondroid metaplasia - used to be thought of as fibroid metaplasia but recently journal publications by hansen et al 201 journal of veterinary pathology showed that Hansen type II is histologically mroe similair to type I than previously thought. This chronic chondroid metaplasai causes a gradual transfer of stress to the annulus, which eventually degenerates over a period of months to years. The degeneration typically leads to dorsal *protrusion* of disk material and compression of the spinal cord. The clinical signs associated with these conditions can be similar since both cause various degrees of spinal cord compression. *The main differences pertain to the acuteness and severity of the resulting clinical syndrome. Type I is typically associated with acute or peracute clinical signs caused by severe contusion or even laceration of the Dura Mater and spinal cord in severe cases. Type II usually leads to more insidious clinical signs secondary to inflammatory changes at the site of compression. Signalment is also different between Type I and II.*

Answer 33

Healing of intestine progresses through the same 4 stages of healing as other tissues: Inflammation, debridement, proliferation and maturation Inflammation & debridement phase - often grouped as a 'lag' phase or a delay in the gain in wound strength Depending on the condition of the bowel, the lag phase generally lasts from 0-4 days after wounding and it is during this time that intestinal wound is at the weakest/most prone to dehisence. If clinical deterioration occurs within the first 4-days post op (usually after 3 days as fibrin lug can degrade after 3 days); suspicion of dehisence should be had. During this lag phase, the wound is most reliant on the suture integrity to prevent leakage After lag phase surpassess, the fibroblast numbers in the wund increase substantially and the amount of collagen in the woundincreases wound strength at a rapid rate

Answer 34

Aims of surgery are: - source ontrol (stop source of contamination) - remove foreing and purulent material from peritoneal space - provide drainage (only if adequate source control cannot be performed) **Source control** - either by RNA or by performing a serosal patch (RNA is more reliable if area of perforation is identified) **Removal of foreing and/or purulent material** - usually by peritoneal laavge with warmed isotonic saline - lavage should be repeated until the fluid is clear (usually several litres) - helps remove bacteria, as wlel as necrotic tissue, clots, fat droplets, toxins and inflammatory mediators **Drainage** - closed suction drainage is indicated onyif inadequate source control is achieved

Answer 35

**70-80%** of liver parenchyma can eb removed and it will regenerate within 6 weeks

Answer 36

AFFERFENT: 1. Hepatic arteries - arise from celiac artery and provide *20%* of the total blood volume entering the liver 2. Portal veins - *80%* of the blood supply Ligation of the hepqatic artery is *non-fatal* - as long as antibiotics are prescribed to prevent anaerobic bacterial colonisation due to decreased poxygen tension within the liver. **Efferent**: Hepatic veins; 6-8 and variable in location

Answer 37

1. **finger fracture technique** The liver parenchyma has proportionally less collagen compared to the larger hepatic vessels within - blunt frcature of the parenchyma with fingers or tissue forceps (after sharp incision of the hepatic capsule) tends to disrupt the hepatic parenchyma whilst preserving vasculature. Exposed vessels and biliary ductules are then ligated using haemoclips or suture. 2. **hepatic lobar dissection technique** 3. **TA stapler technique** Self explanatory. Typically staplers with 60-90mm long cartiridges are used, with 3.5mm staples. Most surgeons prefer the V3(white) over the TA for extra assurance (additional line of staples) but the V3 typically isn't longer than 30mm, and the staples are not as thick. Hypoglycemia may occur after substantial hepatecomty; IV isotonic dextrose at 10ml/kg/hr can help lessen the severity of this. ## Footnote Cartridges come in 4 lengths: - 30mm (V3) - 45mm - 60mm - 90mm Staple sizes: 2.5/1.0mm WHITE (vascular staples have 3 rows) 3.5/1.5mm BLUE 4.8/2.0mm GREEN

Answer 38

- Caudate - Right lateral - Right medial - Quadrate - Left medial - Left lateral

Answer 39

1. Hepatocellular 2. Biliary 3. Neuroendocrine 4. Mesenchymal Of the Hepatocellular tumours, the morphologic forms are; - *massive* - metastatic rate is 0-37% - *nodular* - metastatic rate is 93-100% - *diffuse* - metastatic rate is 93-100% The solitary mass form (massive) is very amenable to surgery alone, and survival times in one study >1460days, irrespective of whether chemotherapy was performed or not. So the best prognosis one could hope for. Prognosis for other histological liver tumour types & for nodular and diffuse forms of hepatocellular type are poor as they are either not amenable to surgical excision or due to metastatic disease.

Answer 40

OCD begins with a failure of endochondral ossification in either the physis or the articular epiphyseal complex that is responsible for long bone epiphyseal formation. Cause of OCD is unknown but is considered multifactorial, with management, genetic and nutritional factors contirbuting to the disease development in young dogs. Osteochondritis dissecans is a sequlae of osteochondrosis, in which a cartillage flap lifts off from the subchondral bone due to a retained cartillage core - with cartillage flaps sometimes becoming detached and mineralising within the joint (termed joint mice when seen on radiographs) OCD commonly occurs in the shoulders, elbows, stifles and hocks. Is commonly bilateral, and as so the contralateral limb should be radiographed even if only unilateral clinical signs are present. SIGNALMENT: large- and giant- breed dogs are commonly affected. Rarely diagnosed in cats or small dogs. Males more commonly affected than females. Clinical signs often develop between 4 and 8 months of age, however some dogs may not be presented for evaluation until they are mature or middle-aged HISTORY: Affected animals usually are seen with unilateral forlimb lameness - gradual onset of lameness that impoves after rest and worsens after excercise. PHYSICAL EXAM: Usually pain localisable to the joint, with msucle atrophy is all that is seen. DIAGNOSIS: Lateral projection radiograph or CT

Answer 41

**PASSIVE** - ***medial and lateral glenohumeral ligaments*** - the medial ligament often appears as a "y" shape with cranal arm cousing caudally from origin at medial surface of supreglenoid tubercle. The caudal arm origin is the medial surface of the scapular neck and joints cranial arm to insert onto the humeral neck - ***surrounding joint capsule*** - ***joint coformation*** - ***synovial fluid cohesin*** **DYNAMIC ACTIVE** Dynamic active stabilisation is provided by contraction of the surrounding cuff muscles - inducing compressino across joint surface as well as increasing joint capsule tension - ***Biceps brachii muscle/tendon*** - ***subscapularis muscle*** - ***teres minor muscle*** - ***supraspinatous muscle*** - ***infraspinatous muscle*** Examination for shoulder instability should be done in an awake patient as well as under anaesthesia. flexion, extension, abduction and rotational stbaility should be assessed. Comparison of right to left shoulder joints should be done. Limb circumduction used to detect for subluxation. **Abduction test: ** - patient in lateral recumbency with forearm extended & shoulder joint in slight external rotation - Limb graudally raised with valgus maneuver - normal test is approx 25degress of valgus movement - abnormal >25degrees, and is often approx 43degrees - importance is determination of difference between contralateral shoulder - *An abnormal result does not always correlate to medial restraint injury - with cases of chronic forelimb lameness having been shown o correlate to an abnormal abduction test in the lame limb - presumably due to disuse atrophy and resultant laxity/loss of strength of the cuff muscles and ligaments*.

Answer 42

SINGLE: **76%** of portocaval shunts - extrahepatic (53%) or intrahepatic (23%) MULTIPLE: **24%** of portocaval shunts Single extrahepatic shunts occur more commonly in **small breed** - either the shunt leaves the portal vein and bypassess the liver, or a splachnic vessel bypasses the portal vein to pass directly to the cava or azygous vein. *Intrahepatic shunts* seen in large dogs (like Labradors). Can be persistent ductus venosus, portal-hepatic or portal-caval shunts. Most intrahepatic shunts are found in the left medial or left lateral lobe and drain into the left hepatic vein. *Acquired shunts* are multiple and occur in response to portal hypertension, but the doberman and german shepherd seem to be over-represented with this condition

Answer 43

Majority of bacteria are **anaerobes** (*Bacteroides and clostridium spp.*) Metronidazole is effective against anaerobes but must be administered at least two days prior to surgery to be effective Prophylactic IV gentamicin (less commonly done in small animal practice) or amoxicillin one hour before and immediatelyt after colorectal surgery is advised. Second generation cephalosporins are effctive against anaerobes and G-ve aerobes (cephazolin)

Answer 44

A = Transverse colon B = Caecum C = Descending colon D = Ileum (note the anti-mesenteric blood vessel indicating this to be ileum) E = Ascending colon F = Rectum G = Aorta H = Jejunal arteries I = Caudal mesenteric artery J = Left colic artery K = Cranial mesenteric artery L = Middle colic artery M = Caudal pancreatic duodenal artery N = Antimesenteric ileal artery (branch of the ileocolic artery) O = Right colic artery P = Cranial rectal artery

Answer 45

- Two-stage surgery with first stage being a ventral midline laparotomy, and stage 2 being perineal approach. STAGE 1 - Arteries supplying caudal colon are ligated (cranial rectal artery = branch of the caudal mesenteric artery) - rectum extending into pelvic canal is bluntly dissected from its attachment - as close a spossible to rectum to avoid damaging parasympathetic nerve fibres - colon is incised at the level of the pubic brim, and each of the bowel is oversewn with 2/0 monofilament in an inverting manner (cushing/connell or lembert suture) and tags left long - then the tags are tied together (from the orad and aborad sections of bowel now) - routine ventral abdominal closure STAGE 2 - Allis tissue forceps inserted into rectum and inverted edge of colon is grasped - Gentle caudal traction will evert the caudal rectum and drag cranial segment with it - incision is made through colon distal to the lesion dorsally through which the tag from the orad section of bowel is located - and careful anastamosis of the orad section of bowel is done to the rectum at the incision site.

Answer 46

**BENIGN** - *Adenomatous polyps* - by far the most common benign tumour in the rectum, may be single or multiple, raised or pedunculated and may be sessile in nature (fixed/immobile) - There is little evidence that adenomatous polyps represent a premalignant lesion in dogs - males and females equally represented - mean age of 6.9yrs at time of diagnosis - Collies seem to be predisposed - Clinically present with haematochezia and irritation/pain in rectum. sometimes are palpable on digital exam. - Polyps do not invade the muscularis - and as such can be excised via rectal eversion surgery using electrosurgery, however larger sessile or raised polyps usually require resectino and anastamosis **MALIGNANT** DOGS: 1. adenocarcinomas (most common) 2. leiomyosarcoma 3. fibrosarcoma CATS: 1. lymphosarcoma (most common) 2. adenocarcinomas 3. mast cell tumours ***Adenocarcinomas*** usually occur in older animals, typically infiltrative, ulcerative or proliferative FOUR histological subtypes recognised in dogs; - solid - acinar - pappillary - mucinous ALL 4 havve a similair biological behaviour Median survival time = 10 months ***Lymphosarcomas*** usually metastasise to the regional lymph nodes, kidneys and liver Prognosis is always poor for these tumours Median survival time = 7 months

Answer 47

1. gentle tissue handling 2. strict aseptic technique 3. meticulous haemostasis 4. elimination of dead space 5. minimising wound tension 6. preservation of vascularity 7. careful approximation of tissues + sharp anatomic dissection (not one of original principles but good to adhere to)

Answer 48

**Monocryl (Poliglecaprone25)** - *70-80%* of its tensile strength in *14 days* - completely absorbed in *90-120 days* **Monosyn (glyconate)** - *50%* loss of tensile strength after *14 days* - completely absorbed *60-80 days* **Polydiaxanone suture (PDS)** - *14%* loss of tensile strength after *14 days* - persists in tissues for *180days or more*

Answer 49

Manual evactuation of the bowels by performing an enema is then followed by; - stool softeners (lactulose) - laxatives - high fibre diets + repeat enemas (become less effective with time) - Prokinetic drugs (cisapride) may help prevent recurrence in some cases after evacuation - Surgery (subtotal colectomy) is a very succesful treatment option

Answer 50

- routine midline laparotomy - colon transected 2-4cm cranial to the pubis and then proximally a one of two levels: 1. immediately distal to ileocolic valve = colocolonic anastamosis 2. proximal to the ileocolic valve = enterocolonic anastamosis With second option above - position of this resection point has been ehavily debated - ileum is active in water and Vitamin B12 and bile salt absorption - ileocaecal valve reduces the access of colonic bacteria to the small intestine - Proximal colon absorbs water along an osmotic gradient and mixes the bowel contents by reverse peristaltic contractions - Distal colon is responsible for storage of faeces As such removal of colon may result in the passage of diarrhoea, which would be axacerbated by removal of the ileum and ileocaecal valve, due to resultant bacterial overgrowth, deconjugation of bile salts and steatorrhoea *Post-op diarrhoea* is only transient and usually* resolves within eight weeks* with most cats start passing soft but well formed faeces within a short time after surgery.

Answer 51

1. Levator ani muscle 2. coccygeaus musccle 3. obturator muscle 4. external anal sphincter muscle

Answer 52

- The cause of the disease remains unknown, however several predisposing factors exist - 97% if affected animals are **entire males** - this could be due to females having a greater strength, size and area of the rectal attachment of the levator ani muscle - age range = 4-17yrs with peak incidence of around eight years - Can occur in any breed but there is an increased ncidence in several breeds: Collies, Boston terriers, Pekes, Boxers, Corgies, old english sheepdogs - Atrophy of Levator ani is considered primary problem, with biopsies of the levator ani having shown histological signs consistent with neurogenic atrophy **Hormonal imbalance** - degenerative myopathy of the muscles of the pelvic diaphragm associated with sex hormones (however a direct link has not been established) - adrogens contibute to hyperplasia of prostate which then has resultant increase relaxin production **Relaxin effects** - a higher expression fo relaxin receptors have been found wthin muscles of diaphragm in dogs with perineal hernias - atrophy of these muscles may be attributable to increased relaxin production **Prostatic enlargement** - leads to constipation and tenesmus - about 43% of patients with perineal hernias have concurrent prostatic enlargement (although also expected in middle to older aged male entire dogs **Chronic consipation** - and straining may place pressure on pelvic diaphragm **Oestrogens** - from ageing testicles may also contribute to slackening of tissues in the pelvic area

Answer 53

- 60% of hernias are unilateral, of these 70% are **right sided** - Hernation is *usually between the external anal sphincter and the levator ani* muscles, and *occasionally between levator ani and cocygeus* muscles - Most hernias contain only pelvic and prostatic fat but sometimes *(~20%)* *may contain organs such as the bladder, intestines or prostate* - Bladder retroflexion is of major concern and should be investigated for as part of work-up (especially those animals who present in an emergent state) - *Rectal dilation* -90%% of cases examined have one wall of rectum dilated in direction of hernial sac - *Rectal deviation* - both walls are deviated into the hernia - *Rectal diverticulum* - muscular breakdown in the rectal wall allowing mucosa to protrude through the muscularis Conservative management: - faecal softeners and enemas will help alleviate clinical signs, but overall conservative management is not very succesful in achieving resolution - bladder retroflexion cases often cannot urinate and are emergent - IV fluids to start diuresis and decrease K+ (+/- insulin/dextrose/calcium gluconate if critically high levels of K+ causing bradyarrythmias) - catheterisation of bladder or paracentesis if required to achieve manual reduction of hernia - an epidural under sedation may help fascilitate reduction of hernia if animal is unable to undergoe GA - surgical correction as soon as animal is stable enough to undergo GA

Answer 54

1. An incision is made over the hernia from tail base to the level of ischium, with hernia contents usually exposed - replace hernia contents (usually mostly fat) 2. Suture placement using large gauge (2-0) polypropylene, nylone or a synthetic absorbable like PDS as follows (all pre-placed sta sutures and then tied at the end once satisfied) - from remnant of cocygeus or levator ani to external anal sphincter - from sacrotuberous ligament to the external anal sphincter - then elevate the internal obturator muscle off the ischial table, enough to reflect dorsally and place sutures to the external anal sphincter - **beware sciatic nerve behind the sacrotuberous ligament** (because of this - most people preger to take bite THROUGH the sacrotuberous ligament rather than around, to prevent sciatic nerve entrapment) - **beware gluteal vessels extending between ligament and sciatic nerve** - **beware as to not perforate rectal wall when placing sutures through external anal sphincter** - **beware pudendal nerve, artery and vein which courses dorsal to internal obturator muscle and ventral to external anal sphincter** - **beware with bilateral repairs not to overstretch the sphinter - these cases Giselle prefers to use polypropelene mesh due to this concern** Additional vasdeferopexy may be warranted if recurrent bladder retroflexion occurs, however it is usually done as a seperate procedure if required POST OP: - Castration is always stgrongly recommended, as risk of recurrence in non-castrated dogs has been 2.7 times greater than in castrated individuals - ensure anal purse string removed - post-op antibiotics is warranted - faecal softeners post-op - elizabethan collar - suture removal 10-14 day post-op

Answer 55

1. **Columnar zone** - contains the anal columns that form longitudinal folds and ridges. 2. **Intermediate zone** - a 1mm irregular scalloped fold between the mucous membrane and the skin 3. **Inner cutaneous hairless zone** - rich in glandular structures 4. **Outer cutaneous hair-bearing zone** - merges with surrounding skin

Answer 56

1. **circumanal glands** NOT IN CATS - *perianal or hepatoid glands* which surround the anus. are subcutaneous glands which are found within zone 3 of the anal canal (inner cutaneous hairless zone) 2. **anal glands** - modified apocrine sweat glands which occur throughout the columnar and intermediate zones (in zones I, II and III) 3. **glands of the anal sac** - lie within walls of anus and open into it. Sacs lie between the external and internal sphincters, opening into the intermediate zone through duct oenings at 5 & 7 oclock

Answer 57

1. perianal adenocarcinoma 2. anal furunculosis 3. pemphigus vulgaris 4. pruritus ani 5. Anal sac disease

Answer 58

1. **Perianal adenoma (hepatoid gland adenomas)** = third most common tumour in dogs. Occurs in **dogs only** as cats do not have circumanal glands. Occur in nodular or diffuse form and are found in the skin under the tail base or around the anus occasionally on the preputial skin. 83% of these seen are in older entire male dogs. They are almost always benign and androgen dependent. *Treatment*: surgical excision + castration, pre-surgical cytoreduction using stillboeastrol can shrink the mass prior to surgery. Antiandrogens (eg delmadinon acetate [tardak] 1-2mg/kg SC, IM can also be used. Radiation; they are very radiosensitice but radiation can damage the nearby colon, resulting in stricture or proctitis. 2. **Adenocarcinomas**. Occur in equal freq male vs females. appear initally like hypertrophy of the anal area, but then rapidly develop into discrete swellings, often multiple, which may invade the pelvic canal and eventually ulcerate. Metastasis to sublumbar lymph nodes, then onto more distant sites thereafter. prognosis is guarded to poor with these - although a few may take some time to regrow or for metastases to develop, making surgery worthwhile. 3. **Anal sac adenocarcinomas** - Rare malignant neoplasms that arise from apocrine glands of the anal sacs. Seene specially in older female dogs. Hihly malignant as well as locally invasice and metastasise to sublumbar LNs also - usually in 90% of cases. Can prdocue hormonlly active substance (PTH-rp) which cand cause secondary pseudo-hyperparathyroidism = hypercalcemia, decrease serum phosphate, with polyuria and polydipsia secondary to renal damage crom hypercalciuria. *Treatment: surgical excision, LN extirpation and chemotherapy* Prognosis is more guarded for dogs with hypercalcaemia. Other tumours in perineal area: - squamous cell carcionma - malignant melanomas - fibrosarcomas - neurofibromyxomas - myxosarcomas - other connective tissue tumours (eg plasmacytoma)

Answer 59

**Indications for TECALBO:** - non-responsive chornic otits externa - failed lateral or vertical ear canal resection - neoplasia involving the horziontal ear canal - congenital or traumatic stenosis of the horizontal ear canal Surgical technique for TECALBO - similair approach as to lateral ear canal resection (T-shaped incision over vertical canal, with circumfrential incision made around *external auditory meatus*, and continued dissection down vertical canal, and along horizontal canal. - Dissect around horizontal canal until you reach *external acoustic meatus* - Be sure to remain close to the perichondrium and avoid the **Retroglenoid vein rostrally** and the **facial nerve caudoventrally** - small branches of the fascial nerve (internal auricular nerves) that penetrate the horizontal ear canal may have to be transected, but should not result in facial nerve paralysis - transect the horizontal ear canal attachment to external acoustic meatus - remove residual epithelium from rim of the external acoustic meatus - with ronguers, remove the ventrorostral portion of external acoustic meautus and extend the osteotomy into the lateral aspe of the osseous bulla - **collect sample of bulla lining/contents for C&S** - with currette; gently remove infected material/tissue from bulla folowed by gentle lavage with saline - **avoid curreting the dorsal and dorsal medial area of the tympanic cavity - to avoid damage to the cochlear and round windows**

Answer 60

- An inciions is made on ventral aspect of head, positioned directly over the palpable tympanic bulla - **Avoid transection of the large lingual and fascial veins (LV & FV) located either side ofr the bulla** - **Beware of hypoglossal nerve - often visualised and can be retracted medially** - Entry into the bulla through the ventral wall is made using a steinmann pin or a spinal burr, ensuring the pin or burr is directed laterally to avoid accidental penetration of the oval promontory/other vital structures on dorsum of tympanic membrane - Lempert ronguer is used to continue the bulla osteotomy via the initial hole, and then ronguers used to remove the septum (in cats only as dogs have an incomplete septum which does not impede access to the dorsolateral compartment (epitympanum). - **Care must be taken to not disturb the sympathetic nerve fibers that pass through the occiptotemporal fissue located on the dorsal caudomedial aspect of the bulla (yellow fibres in diagram below)** The most dorsal aspect of the septum may be left intact, thus protecting the sympathetic nerves as they apss in this region. - The presence of near complete septum dividing the hypotympanum/epitympanum in cats makes the traditional LBO more challenging and incomplete removal of bulla lining from the hypotympanum has been reported after LB in cats. - Polyps typically arise from within the eustachian tube (auditory tube) or the nasopharyngeal region and grow upward into the auditory tube. As such the dorsolateral compartment needs to be entered to allow for complete polyp removal as the round window is located within this compartment.

Answer 61

1. Mentation 2. Heart Rate (HR) 3. Pulse quality 4. Mucous membranes (colour and tackiness) 5. CRT 6. Extremity temperature

Answer 62

**1. Hypovolemic:** a decrease in circulating blood volume - Haemorrhage - Severe dehydration - Trauma **2. Cardiogenic:** a decrease in forward flow from the heart - Congestive heart failure - Cardiac arrhythmia - Cardiac tamponade - Drug overdose (eg. anaesthesia, beta-blockers, calcium channel blockers) **3. Distributive:** a marked decrease or increase in systemic vascular resistance or maldistribution of blood - Sepsis - Obstruction (heartworm disease, saddle thrombosis) - Anaphylaxis - Catecholamine excess (pheochromocytoma, extreme fear) - Gastric dilatation volvulus **4. Metabolic:** deranged cellular metbaolic machinery - Hypoglycemia - Cyanide toxicity - Mitochondrial dysfunction - Cytopathic hypoxia of sepsis **5. Hypoxemic:** decrease in oxygen content in arterial blood - Anaemia - Severe pulmonary disease/compromise - Carbon monoxide toxicity - Methemoglobinemia

Answer 63

Calcaneal tendon rupture **Type 1** * Complete disruption of the entire tendon usually as the result of trauma * Maximal flexion of hock seen with stifle extension * Separate tendon ends are palpable through skin **Type 2** * These injuries show a variable degree of increased hock flexion with stifle extension * Further subclassified into 2a, 2b and 2c **Type 2a** * Incomplete separation between gastrocnemius MUSCLE and tendon **Type 2b** * Where there is total disruption of the tendon with paratenon still intact **Type 2c** * SDFT intact – increase hock flexion with digit hyperflexion **Type 3** * Represents an earlier stage of Type 2c – whereby the distal end of the gastrocnemius tendon is ruptured

Small Animal Surgery - Residency (my own cards) Flashcards

(96 cards)