Urinary Tract Diseases of the Horse Flashcards
(39 cards)
What crystals are normal to find in horse urine?
Calcium oxalate crystals
When do Calcium oxalate crystals become problematic in the horse?
When the crystals aggregate together into a urolith and cause abrasions to the bladder wall and subsequent cystitis
OR
When the uroliths pass into the urethra and cause partial or complete obstruction
What are the clinical signs associated with urolithiasis in horses?
- Frequent urination
- Passing of small volumes
- Straining to urinate
- Blood in the urine
How can urolithiasis be diagnosed in horses?
- Ultrasound evaluation per rectum
- Endoscopy of the bladder
What is the treatment for urolithiasis in FEMALE horses?
- Pass forceps into the bladder and break up the stones to allow for pieces to be manually removed or lavaged out
- A cystotomy under general anesthesia may be necessary to remove extra large uroliths
What is the treatment for urolithiasis in MALE horses?
- Pass a catheter to push the stones back into the bladder before lavaging it out
- If a stone is stuck in the urethra, then a perineal urethrotomy or urethrostomy may be needed to remove it. Complications of this sx are stricture and fistula formation
- Lithotripsy (U/S shockwaves) can be used to break up uroliths and facilitate removal
Where is the most common site of lodgement for a urolith in the male horse?
at the point of urethral narrowing behind the ischium
How can urolithiasis be prevented in horses?
- Dilution of urine: increase water intake by increasing salt intake
- Acification of urine: adding Vit C and potassium aspartate
- Decreased minerals in diet: reduce grain and decrease calcium
What is the difference between a urethrostomy and a urethrotomy?
Urethrotomy: the surgical incision into the urethra and then allowed to close either through primary or secondary intention
Urethrostomy: the surgical incision into the urethra and then tacking of the mucosa to the skin to create a permanent urethra opening
What are the complications associated with both a urethrostomy and a urethrotomy?
- Stricture formation: usually occurs 6m - 1 year after surgery
This can be redone, but stricture formation is then even more likely after this - Fistula formation
What age is bladder rupture most commonly seen in horses?
- Neonatal foals: more common in colts (believed to be due to narrower pelvis than filly’s)
- Secondary to urolithiasis at any time
- Mares post parturition (not always associated with dystocia)
What is the typical presentation of a foal with a ruptured bladder?
- Clinically normal at birth
- Then 1-5 days, clinical signs arise as uroabdomen develops and associated electrolyte imbalances: depressed, anorexic, abdominal distension, mild colic, dehydration
Where in the bladder is the most common site for tearing, in foals?
- Small tear at the dorsal neck of the bladder
How can a ruptured bladder be diagnosed in foals?
- Clinical signs and history
- Blood analysis: hyperkalemia, low Na and Cl, metabolic acidosis, high serum creatinine
note: the hyperkalemia is what can kill the foal if left untreated as it can cause arrhythmias
- Ultrasound
- Abdominocentesis
What is the treatment and prognosis to a ruptured bladder in a foal?
- Stabalize the foal with fluid therapy, correction of electrolyte imbalances, slow abdominal drain and glucose supplementation
- evaluate for concurrent diseases: PAS (perinatal asphyxiation syndrome) or septicemia
- midline laparatomy under GA
Prognosis: good to excellent
What is considered to be the most common malformation of the equine urinary tract?
Congenital patent urachus: due to increased tension on the cord or torsion can lead to dilatation and failure to close at birth
What are the clinical signs associated with a patent urachus in a foal?
- persistently moist umbilicus after birth
- urine leaking from the umbilicus
- signs of systemic disease (septicemia, joint ill and pneumonia)
How can a patent urachus be diagnosed in a foal?
- Clinical signs, exam and history
- Ultrasound
What is the treatment for a patent urachus in a foal?
Dependent on whether there is infection or not:
- No Infection: navel dip with 0.5% chlorhexidine 2-4x a day
+/- systemic antibiotics with regular U/S to monitor changes
- Infection: broad spectrum antibiotics, and if urine leakage continues after 7 days of medical therapy then surgical exploration and resection of the urachus and umbilical vessels may be needed
What 2 diseases are most commonly found in the upper urinary tract of the horse?
- Acute renal failure
- Chronic renal failure
What 3 diseases are most commonly found in the lower urinary tract of the horse?
- Cystitis/ Urethritis
- Uroliths
- Incontinence
What are the causes of Acute renal failure in the horse?
Divided into Pre-renal, Renal and Post-renal causes
Pre-renal: Decreased perfusion
- Hypovolemia, hypotension, dehydration, sepsis/ endotoxemia, DIC and volume redistribution
Renal:
- Toxins: exogenous toxins (aminoglycosides, NSAID’s, acorns, Cantharidin) or endogenous toxins (Myoglobin/ Hemoglobin and Endotoxin)
- Nephritis: Bacterial or Immune mediated
Post-renal: Obstruction
- Urolithiasis, neoplasia, bladder paralysis
What are the causes of Chronic renal failure in the horse?
- Residual damage from untreated acute renal failure
- Abscesses
- Neoplasia
- Infarct/ Haemorrhage
What are the clinical signs associated with acute renal failure in the horse?
Non-specific usually
- Depression
- Fever
- Anorexia
- Early polyuria
- Anuria
