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Flashcards in Equine urinary tract Deck (74)
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Describe the epidemiology of urolithiasis and obstructive disease in horses

- Adults: mean age ~10yo
- Foals: reported after bladder rupture repair
- Males, mainly geldings
- No breed predisposition


Describe the location of uroliths in the horse

- 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


What is the most common composition of uroliths in horses and how do these form?

- Calcium carbonate more common than calcium phosphate
- Form from nidus of inflammation, infection or fibrosis


Compare the nephroliths and ureteroliths in horses

- 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


Describe the clinical signs of unilateral renal/ureteral calculi

- Mild clinical signs e.g. recurrent colic or none
- Azotaemia usually absent
- Intermittent/persistent gross haematuria


Describe the clinical signs of bilateral renal/ureteral calculi

- 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)


Describe the diagnosis of renal/ureteral calculi in the horse

- 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


Describe the treatment of nephroliths in the horse

- Surgery: Nephrotomy/uretotomy
- Unilateral nephrectomy if no azotaemia
- Electro hydraulic lithotripsy for ureteroliths: electrical impulse causes shock waves to break stone, fragments flushed out


What is the most common type of urolithiasis in the horse?

Cystic calculi


Compare the gross appearance of calcium carbonate and calcium phosphate calculi

- Carbonate: singe, large spiculated stones, fragment
- Phosphate: smooth, grey-white stone, do not fragment


List the risk factors for crystal precipitation in the horse

- Supersaturation of urine
- Prolonged urine retention
- Promotors of crystal growth
- Tissue damage
- Nidus present
- Fluid therapy containing calcium


Describe the clinical signs of cystic calculi in the horse

- Dysuria
- Stranguria
- Pollakiuria
- Haematuria esp. post exercise
- Restlessness, grunting, tenesmus during urination


Outline the diagnosis of cystic calculi in the horse

- Rectal palp: firm oval mass in lumen, rare to get multiple calculi
- Transrectal ultrasonography


Outline the treatment options for cystic calculi in male horses

- 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)


Outline the treatment options for cystic calculi in mares

- 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


Where do urethral calculi commonly lodge in horses?

Ischial arch in males or distal urethra


Compare the presentation of cystic and urethral calculi in horses

Urethral tend to cause a more acute problem


Describe the diagnosis of urethral calculi in horses

- 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


In the horse, what is a possible consequence of urethral calculi and how is this diagnosed?

- 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


Describe the treatment options for urethral calculi

- Ischial arch: standing, sedated, epidural perineal urethrotomy
- Lower urethral calculi: retrieval with endoscopic instruments e.g. Basket forceps


Outline the prevention of calculi in horses

- 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


What conditions does cystitic occur secondary to in the horse?

- Urolithiasis
- Bladder neoplasia
- Bladder paralysis
- Anatomical defect in bladder/urethra
- Instrumentation of urinary tract e.g. catheterisation, endoscopy


Describe the clinical signs of cystitis in the horse

- Dysuria: pollakiuria, stranguria, haematuria, pyuria
- urine scalding/urine cystals (mares perineum, males HL)


How does bladder paralysis lead to cystitis in the horse?

Incomplete emptying, sediment remains in bladder leading to secondary issues


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


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


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


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


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


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