Equine Urogenital Surgery: Urolithiasis & Foals Flashcards
What is the most common type of cystic calculi seen in horses? What is the most common clinical presentation?
Type 1 - calcium deposits into yellow, spiculated structures
- hematuria after exercise
- stranguria - posturing to urinate without passing urine
- colic
How are cystic calculi diagnosed?
- rectal palpation - just inside rectum
- endoscopy
- U/S - bladder, kidney (nephroliths have high likelihood of recurrence)
What are 3 options for treating cystic calculi in horses?
- surgery - cystotomy, perineal urethrotomy (blocking urethra)
- mares - manual removal
- lithotripsy
How are horses prepared for cystotomies? What are 2 options for approach?
fast for 24-48 hours to decrease abdominal fill
- caudal ventral midline + parapreputial - enter abdomen on midline
- parainguinal - cranial edge of inguinal ring
Where is the bladder found in the abdomen? How are cystotomies performed?
caudal abdomen/pelvic inlet
- facilitate exteriorization by distending the bladder with saline and allowing it to empty
- place stay sutures to stretch the bladder and apply traction
- enter bladder and gently peel stones off of the mucosa (spicules adhere to mucosa!)
- lavage the bladder to reduce subsequent stone formation
- close with a 2 layer inverting pattern - Cushing or Lembert
What do smaller stones most commonly cause? What clinical signs are associated? How are they diagnosed?
urethral obstruction –> posturing to urinate with no passage or urine
- distended bladder on rectal palpation
- endoscopy
- palpation
What are 2 indications for perineal urethrotomies?
- permit urine flow with urethral obstructions or atonic bladders
- remove small uroliths - manual, lithotripsy, challenging!
In what 4 ways are horses prepared for perineal urethrotomy? Where is the incision placed?
- standing sedation
- caudal epidural anesthesia + local blocks
- evacuate rectum to avoid contamination
- pass a urinary catheter into the bladder
incise perineum 4-6 cm below anus and extend distally 6-8 cm below the ischial arch –> dissect to penile body and incise into urethral lumen
What are 3 options for removing uroliths from a perineal urethrotomy?
- extract manually
- endoscopic - pass endoscope through PU into bladder, use basket to remove
- lithotripsy - laser through endoscope to break the stones
What is the difference between a temporary and permanent perineal urethrotomy?
TEMPORARY - heals by second intention within 2-3 weeks, hematuria for 2 weeks common with incision into corpus spongiosum
PERMANENT - urethrostomy, done for fabulous urolithiasis, suture urethral mucosa to the skin, urine scalding common
What are the major causes of uroperitoneum in foals?
- bladder rupture - common during parturition, dorsal aspect of bladder
- patent urachus - SQ edema
What signs are associated with uroperitoneum in foals? When is it most commonly seen?
- EARLY - depression, inappetence, straining
- PROGRESS - colic, abdominal distension, preputial swelling
- tachycardia, tachypnea, bradycardia, arrhythmia
- lower volume + straining with urination
first 48 hours of life
What are the 3 most common etiologies of uroperitoneum? In colts?
- trauma
- septic omphalitis
- increased abdominal pressure during foaling
narrow pelvis and longer urethra
What are 5 options for diagnosing uroperitoneum?
- blood chemistry - azotemia
- acid/base status - metabolic acidosis
- electrolytes - hyperkalemia, hyponatremia, hypochloremia
- imaging - contrast radiography, U/S
- peritoneal fluid - peritoneal:plasma creatinine >2:1
What ECG findings are indicative of uroperitoneum?
hyperkalemia –> peaked T wave, loss of P wave, wide QRS complexes
What 3 medical treatments are recommended for uroperitoneum?
- correct electrolyte imbalance - 0.9% or 0.45% NaCl, 5% dextrose, calcium gluconate, insulin –> treat hyperkalemia before life-threatening arrhythmias
- abdominal drainage - remove urine, peritoneal lavage, must be slow enough to not alter abdominal pressure too fast
- urinary catheter
What is the treatment of choice for uroperitoneum? What is commonly recommended after?
surgical management once patient is stabilized with a serum K <5.5 - good prognosis if otherwise healthy
- indwelling urinary catheter
- antibiotics - prophylactic or existing infection
What is the urachus? How does it develop?
conduit for fetal urine to travel from the bladder to the allantoic cavity
should close at birth –> incomplete closure common with foals –> moist umbilicus, urine stream during urination
What are the 3 major causes of patent urachus?
- congenital malformation
- omphalitis
- septicemia causes local sepsis in the umbilicus
What conservative treatment options are there for patent urachus? What is recommended?
chemical cauterization with silver nitrate sticks + 7% iodine dip and antibiotics
surgical - umbilical resection
What is omphalophlebitis? What are common clinical signs? How is it diagnosed?
umbilical remnant infection
- heat, swelling, pain
- ventral edema
- purulent discharge, fever
U/S of umbilical structures
When is surgical treatment recommended for omphalophlepbitis? What is done?
severe, non-responsive to medical treatment
umbilical resection
How is an umbilical resection performed?
- fusiform incision around umbilicus
- resect bladder tip and enlarged umbilical vessels
- oversew and invert urachus to reduce contamination
How can a non-reducible umbilical hernia be differentiated from an infection?
U/S - may have bowel entrapment
