Equine urinary tract Flashcards
(74 cards)
1
Q
Describe the epidemiology of urolithiasis and obstructive disease in horses
A
- Adults: mean age ~10yo
- Foals: reported after bladder rupture repair
- Males, mainly geldings
- No breed predisposition
2
Q
Describe the location of uroliths in the horse
A
- 84% in bladder, 60% remain in bladder, 24% pass into urethra to cause obstruction
- 16% in renal pelvis, 12% within renal pelvis, 45 causing ureteral obstruction
3
Q
What is the most common composition of uroliths in horses and how do these form?
A
- Calcium carbonate more common than calcium phosphate
- Form from nidus of inflammation, infection or fibrosis
4
Q
Compare the nephroliths and ureteroliths in horses
A
- Nephro: usually within/adjacent to renal pelvis, small passed into bladder with no signs
- Uretero: probably nephro that moved into ureter, enlarge over time, lodge in distal ureter, may be palpated per rectum
5
Q
Describe the clinical signs of unilateral renal/ureteral calculi
A
- Mild clinical signs e.g. recurrent colic or none
- Azotaemia usually absent
- Intermittent/persistent gross haematuria
6
Q
Describe the clinical signs of bilateral renal/ureteral calculi
A
- Hx of NSAID use
- Usually CKD before presentation: weight loss, PU, poor performance, reduced appetite, lethargy
- Uncommon signs: obstructive disease leads to colic, haematuria, lumbar pain, HL lameness, chronic azotaemia (oral ulceration, excessive dental tartar, melaena)
7
Q
Describe the diagnosis of renal/ureteral calculi in the horse
A
- Often incidental at PM, esp. if UUT
- Rectal exam may show turgid ureter (not usually palpable - able to feel = abnormal) +/- ureterolith, increased renal size
- Blood biochem: azotaemia, isosthenuria in CKD, no azotaemia if unilateral
- Urinalysis: pigmentation/microscopic haematuria
- Bacterial culture: rule out UTI
- Ultrasonography transabdo: nephroliths, dilation of renal pelvis, fibrosis but may miss small stones <1cm
- Transrectally: ureteral dilation and lithiasis
8
Q
Describe the treatment of nephroliths in the horse
A
- Surgery: Nephrotomy/uretotomy
- Unilateral nephrectomy if no azotaemia
- Electro hydraulic lithotripsy for ureteroliths: electrical impulse causes shock waves to break stone, fragments flushed out
9
Q
What is the most common type of urolithiasis in the horse?
A
Cystic calculi
10
Q
Compare the gross appearance of calcium carbonate and calcium phosphate calculi
A
- Carbonate: singe, large spiculated stones, fragment
- Phosphate: smooth, grey-white stone, do not fragment
11
Q
List the risk factors for crystal precipitation in the horse
A
- Supersaturation of urine
- Prolonged urine retention
- Promotors of crystal growth
- Tissue damage
- Nidus present
- UTI
- Fluid therapy containing calcium
12
Q
Describe the clinical signs of cystic calculi in the horse
A
- Dysuria
- Stranguria
- Pollakiuria
- Haematuria esp. post exercise
- Restlessness, grunting, tenesmus during urination
13
Q
Outline the diagnosis of cystic calculi in the horse
A
- Rectal palp: firm oval mass in lumen, rare to get multiple calculi
- Transrectal ultrasonography
14
Q
Outline the treatment options for cystic calculi in male horses
A
- Standing or GA depending on site of calculus
- Standing: perineal urethrotomy, pararectal cystostomy (not recommended), electro hydraulic, shockwave or laser lithotripsy
- GA: laparoscystotomy via parapreputial or midline incision, laparaoscopic or laparoscopic assisted cystotomy, urethrotomy for distal urethral calculi)
15
Q
Outline the treatment options for cystic calculi in mares
A
- Manual extraction of calculi <10cm under standing sedation and epidural anaesthesia
- Fragmentation via electro hydraulic or laser lithotripsy
- Sphincterectomy or dorsal urethra for large stones
- Laparoscystotomy rarely required
16
Q
Where do urethral calculi commonly lodge in horses?
A
Ischial arch in males or distal urethra
17
Q
Compare the presentation of cystic and urethral calculi in horses
A
Urethral tend to cause a more acute problem
18
Q
Describe the diagnosis of urethral calculi in horses
A
- Clinical signs: colic, frequent attempts to urinate, blood at urethral orifice
- Palpable calulus in penis
- Rectal examination: turgid, full bladder
- Confirm by passing catheter and endoscope
19
Q
In the horse, what is a possible consequence of urethral calculi and how is this diagnosed?
A
- Bladder rupture if not recognised early
- Signs: depression, anorexia
- Clin path: electrolyte imbalances, azotaemia
- Peritoneal creatinine >2x serum creatinine
- Palpation of empty bladder on rectal exam
20
Q
Describe the treatment options for urethral calculi
A
- Ischial arch: standing, sedated, epidural perineal urethrotomy
- Lower urethral calculi: retrieval with endoscopic instruments e.g. Basket forceps
21
Q
Outline the prevention of calculi in horses
A
- Remove calculus, and debris
- Antimicrobials if UTI/recurrent cystitis after urolith removal
- Dietary management: reduce calcilum absorption, avoid calcium supps, avoid alfalfa, promote diuresis (add salt to concentrate ration, warm water in winter)
- Urinary acidification efficacy unproven, not really an option in horses
22
Q
What conditions does cystitic occur secondary to in the horse?
A
- Urolithiasis
- Bladder neoplasia
- Bladder paralysis
- Anatomical defect in bladder/urethra
- Instrumentation of urinary tract e.g. catheterisation, endoscopy
23
Q
Describe the clinical signs of cystitis in the horse
A
- Dysuria: pollakiuria, stranguria, haematuria, pyuria
- urine scalding/urine cystals (mares perineum, males HL)
24
Q
How does bladder paralysis lead to cystitis in the horse?
A
Incomplete emptying, sediment remains in bladder leading to secondary issues
25
Describe the diagnosis of cystitis in the horse
- Physical examination
- Rectal palpation
- Urinalysis: bacterial C+S (>10,000cfu/ml in mid-stream catch/catheter sample), sediment exam within 30-60mins of collection (10+ leukocytes/hpf, not feasible in first op. practice)
- Ultrasonography: wall thickened, uroliths, masses
- Cystoscopy: mucosal damage, masses
26
List the organisms commonly involved in cystitis in horses
- E coli
- Proteus spp
- Klebsiella spp.
- enterobacter spp
- Streptococcus spp
- Staphylococcus spp
- pseudomonas aeruginosa
- Corynebacterium renale (RARE)
- Candida spp in sick neonates
27
Describe the treatment of cystitis in horses
- Long term ABs (4-6 weeks)
- TMPS, penicillin
- Bladder lavage
- Treat primary problem e.g. urolithiasis, sabulous urolithiasis
28
What is sabulous urolithiasis?
Aka sabulous cystitis: deposition of mucous and salts in bladder, sand-like/slurry material deposited in the badder - abnormal quantities of sediment, mostly calcium carbonate
29
Explain how sabulous urolithiasis may lead to cystitis
- Constant mucosal irritation from sand
- Prevents complete bladder emptying
- BActerial ammonia production in the sediment
- Stretching/inflammation of bladder wall negatively impacts detrusor muscle function leading to more crystal accumulation
30
How does sabulous urolithiasis develop?
- May be idiopathic bladder paralysis syndrome
- Or secondary to neurological disease affecting bladder emptying: EHV1, polyneuritis equi, EPM, sacral Fx, osteomyelitis, illicit tail block
31
Describe the clinical signs of sabulous cystitis in the horse
- Urinary incontinence (may be primary or secondary)
- HL weakness/staxia
- Generally urine scalding
32
Describe the diagnosis of sabulous cystitis
- History and clinical signs
- Rectal examination demonstrates flaccid bladder full of sediment
- Endoscopic examination of bladder for confirmation
33
Discuss the prognosis of sabulous urolithiasis in the horse
- Poor
- Pathological changes generally irreversible
- May be able to fix bladder paralysis depending on primary cause
- Long term management and treatment required, may need periodic lavage of bladder
34
Describe the treatment of sabulous urolithiasis in the horse
- Options for end-stage neuro-myogenic bladder dysfunction same regardless of cause
- Aim to encourage bladder emptying while hoping for improvement in bladder reflex
- Bladder lavage: repeat with large volumes of sterile saline
- Antimicrobial therapy based on urine C+S, intially TMPS over a few weeks (even if no UTI at this stage - high risk)
- NSAIDs
- Low calcium diet
- Bethanecol suggested but not licensed in horse
35
Describe the clinical signs of pyelonephritis in the horse
- RARE
- Signs may relate to underlying cause
- Haematuria, pyuria rather than strang/pollakiuria
- Pyrexia, weight loss ,anorexia, depression
36
What conditions is pyelonephritis usually associated with in the horse?
- Uro/nephro/ureterolithiasis
- Recurrent cystitis
- Bladder paralysis
- Bladder neoplasia/FBs
37
Describe the diagnosis of pyelonephritis in the horse
- Same as cystitis
- CBC and biochem
- Cystoscopy to evaluate ureteral openings, catheterise and sample individually
- Ultrasound of kidneys, bladder and ureters (may identify uroliths)
38
List the organisms involved in pyelonephritis in the horse
- Those as for cystitis
| - Plus haematogenous septic nephritis: Actinobacillus equuli, Strep equi equi, Rhodococcus equi, Salmonella spp.
39
Describe the treatment of pyelonephritis in the horse
- Prolonged antimicrobials based on C+S
- If unilateral, nephrectomy
- Bilateral rarely treated successfully
40
List the differentials for haematuria in the horse
- Vascular malformation
- UTI
- Urolithiasis
- Neoplasia
- Exercise
- Oxidation
- Nephrotoxicity e.g. NSAIDs
- Urethral defects
- Idiopathic
41
Explain oxidation as a differential for haematuria in the horse
Horse urine oxidised after exposure to air, snow bedding (due to pyrocatechin) - turns red-brown
42
Describe urethral defects as a cause of haematuria in the horse
- Rent at proximal urethral or ischial arch in males
- Pathophysiology unknown, may be traumatic, iatrogenic (e.g. catheterisation)
- Blowout of corpus spongiosum penis into urethral lumen
43
Describe idiopathic haematuria in the horse (presentation, cause)
- Sudden onset, potentially life threatening
- Haemorrhage from 1 or both kidneys leads to blood clots in urine
- Cause undetermined, may be neoplastic, arteriovenous or arterioureteral fistulae
- No other signs of disease
- Haemorrhage can be episodic
44
Describe the diagnosis of idiopathic haematuria
- Exclude other diseases
- Signs of acute blood loss: tachypnoea, tachycardia, pale MM
- Rectal palp shows enlarged irregular bladder
- Endoscopy to confirm blood from kidneys
- Ultrasonography: identification of renal pathology
- Renal biopsy may be helpful but will cause more bleeding
45
List the diagnostic methods for the investigation of haematuria in the horse
- Physical exam
- Rectal palp
- Haem and biochem
- Urinalysis: differentiate between haemoglobin, blood, myoglobin
- Cystoscopy
- Ultrasonography of kidneys and bladder
- Assess timing of haematuria
46
How can haematuria of glomerular origin be differentiated from haematuria from another origin in the horse?
- Glomerular: variation in RBC size, shape and Hb content, present of Hb casts (RBC+Hb+Tamm-Horsfall protein)
- Bleeding from other sites more uniform RBC population
47
Outline how the timing of haematuria may indicate the origin in the horse
- Throughout: haemorrhage from kidneys, ureter or bladder
- Beginning of urination: lesions distal to urethra
- At end of urination: lesion in proximal urethra or bladder
48
Describe the treatment of idiopathic haematuria in the horse
- Supportive care for blood loss e.g. blood transfusions
- Haemostatic meds e.g. aminocaproicacid, formalin
- Corticosteroids if suspect immune mediated cause
- If unilateral: nephrectomy, but risk of other kidney being affected later (esp in Arabs)
49
Describe the treatment of urethral rents in horses
- Often haematuria resolves spontaneously
| - If persists >1month or significant anaemia, temporary sub-ischial urethrotomy successful
50
Describe the clinical signs of urethral rents in the horse
- Haematuria at start/end of urinatioin
- Periurethral accumulation of urine (rare)
- No stranguria or pollakiuria
51
How are urethral rents diagnosed?
Urethral endoscopy and contrast radiography
52
List the differentials for pre-renal pigmenturia in the horse
- IMHA
- Piroplasmosis
- Anaplasmosis
- Drug toxicities
- Oxidative damage
- Liver disease
- Haemolytic uraemic synrome
- Rhabdomyolysis
53
List the post-renal differentials for pigmenturia in the horse
- Urolithiasis
- Cystitis
- Urethral rents
- Vaginal varicoceole/genital tract disease
54
What is the most common cause of PUPD in the adult horse?
Apparent psychogenic polydipsia
55
List the differentials for PUPD in the adult horse
- Psychogenic polydipsia
- PPID
- Chronic renal failure
- Hepatic insufficiency
- Diabetes mellitus
- Diabetes insipidus
- Physiological causes
56
In a horse presented for PUPD, would would anaemia, elevated BUN (urea >15mmol/L, creatinine >300mmol/L), hypercalcaemia, isosthenuria and a low urine creatinine:serum creatinine ratio be suggestive of?
Chronic renal failure
57
In a horse presented with PUPD, what would polycythaemia be suggestive of?
Dehydration, suggesting PU is primary problem rather than PD, i.e. diabetes insipidus
58
In a horse presented with PUPD, what would neutrophilia be suggestive of?
Glucocorticoid response or inflammatory disease
59
In a horse presented with PUPD, what are the differentials for low urea and creatinine and how can these be differentiated?
- Hepatic insufficiency
- Or psychogenic PD and medullary washout
- Differentiate based on GGT, GLFH and bile acids
60
In a horse presented with PUPD. what would persistent hyperglycaemia be suggestive of?
PPID
61
In a horse presented with PUPD, what are the differentials for hypercalcaemia?
- Chronic renal failure
| - Paraneoplastic causes
62
What causes of PUPD produce hyposthenuric urine in the horse?
Diabetes insipidus and psychogenic polydipsia
63
What causes of PUPD may cause glucosuria in the horse?
- Diabetes mellitus
- PPID
- Acute stress
- A2As
64
Compare the urine creatinine: serum creatinine ratio in horses with dehydration vs CRF
- Dehydration: increased ratio
| - CRF: lower ratio
65
Describe the clinical signs of psychogenic polydipsia in the horse and how is it diagnosed?
- Significant PU, often flooded stables
- PD as a stable vice
- May be result of excessive salt consumption
- Diagnosis of exclusion
66
Describe the management of psychogenic polydipsia in the horse
- Restrict salt intake
- Restrict water intake
- Alleviate boredom
- Increase feeding frequency of roughage
67
Outline the mechanisms by which PPID causes PUPD
- High cortisol → hyperglycaemia → osmotic diuresis
- Cortisol antagonism of ADH in collecting ducts
- Adenoma growth may impinge on posterior pituitary and hypothalamus leading to decrease ADH → central diabetes insipidus
68
Explain the diagnosis and treatment of PPID
- Plasma ACTH
- Positive if >29pg/ml most months, >47pg/ml in Aug, Sept, Oct
- Treat with pergolide, recheck ACTH in 4 weeks
69
List the differentials for a foal that is weak, trembling, has a distended abdomen, bradycardic a few days after birth?
- Bladder rupture
- Sepsis
- PAS
- Persistent meconium impaction
- Colic for other reasons
70
Describe the clinical signs of bladder rupture in a foal
- Normal at birth
- First 24-36hours tranguria/pollakiuria
- Day 2-4 dull demeanour, abdomianl distension
- May void small amounts of urine
- Cardiac arrhythmias e.g. bradycardia due to hyperK
- Muscle fasciculations
- Colic
- Sepsis
71
What diagnostic investivation findings would be likely in a rupture bladder in a foal?
- HyperK, high creatinine, low Na and Cl
- Metabolic acidosis
- Abdominocentesis shows periteonal:serum creatinine ratio >2:1
- Abdominal ultrasound shows large amounts of free fluid in abdomen and collapsed bladder
- ECG shows hyperK related changes (bradycardia, wide WRS, prolonged P wave)
72
Describe the treatment for a rupture bladder in a foal
- Stabilise pre-op: IV NaCL 0.45-0.9% +5% glucose 1-3L
- If hyperK (>5.5mEq/l): IV Ca gluconate 1ml/kg over 10 mins, IV NaHCO3 1-2mmol/kg over 15 mins, 50% dextrose IV 2ml.kg over 5 mins, insulin if significant ECG abnormalities or poor response to initial fluids
- Drain urine from abdomen pre-op
- Broad spec ABs
- Consdier gastric ulcer prophylaxis
- Ensure passive transfer of Abs occurs
- Surgery to repair defect, remove enlarged umbilical structures
- Place indwelling catheter for 48 hours to decrease bladder distension at repair site
73
Discuss the prognosis for bladder rupture in the foal
- If non-septic, good prognosis
- 95% success rate if treated early and otherwise healthy
- If concurrent infection of GI issue, 50%
- In septic or premature, complications e.g. peritoniitis, incisional complications, adhesions more common
- Repeat ruptures can occur
74
Explain the haematological and biochemical parameters that may be abnormal in a foal affected by placental disease
- Serum creatinine may be 30-40% higher in first 3 days
- Do not worry if otherwise healthy and urinating normally
- If does not fall after 3 days, investigate renal causes
