Obstructive Urinary Tract Disease Flashcards
What is the most significant cause of renal disease and acute uremia in cats?
Ureteral obstruction by calcium oxalate stones or non-mineralized debriss
What is the normal diameter of a feline ureter?
0.4mm
What is the normal diameter of a canine ureter?
1-3mm
Why are cats more predisposed to ureteral obstruction than dogs?
Ureter size
Does an acute unilateral ureteral obstruction usually present clinically?
No
What is more common, acute unilateral or bilateral ureteral obstruction?
Unilateral
How do the kidneys look in acute bilateral ureteral obstruction?
Bilaterally enlarged and painful
What is big kidney little kidney syndrome?
Unilateral atrophy due to past injury and fibrosis and contralateral hypertrophy due to an acute obstruction
What obstructive kidney disease carries the most guarded prognosis?
Bilateral CKD with concomitant ureteral obstruction
What is the typical presenting complaint for ureteral obstruction?
Severe acute uremia (anorexia, deprression, vomiting, uremic odor, lethargy, oligo/anuria), Ureterocolic signs
What age group of cats especially like to get ureteral obstruction?
> 7 years
Worse if they have concurrent CKD
Can ureteral obstructions be incidentally diagnosed on ultrasound?
Yes- may not have clinical signs yet
T/F: Radiographs are always useful for diagnosing ureteral obstruction.
False- depends on species and severity/type of obstruction
What is the percentage rate of false negatives for diagnosing ureteral obstruction on survey radiographs?
20-30%
What are some things to look for when assessing radiographs for ureteral obstruction?
Radiodensities in the retroperitoneal space, expansion of the retroperitoneal space, marked renal asymmetry
What type of stone are you most likely going to see on radiographs?
Calcium oxalate
What is the principle feature of ureteral obstruction when assessing with ultrasound?
Hydronephrosis and dilation of the proximal ureter
How sensitive is ultrasound for diagnosis of ureteral obstruction?
70-80%
How long must an animal be obstructed for before you get ultrasonographic changes?
4-7days
What radiographic modality is useful to help define the indication and location for surgical intervention?
Antegrade pyelography or CT
What is antegrade pyelography?
Incorporates ultrasound guided pyelocentesis and antegrade injection of positive contrast media into the renal pelvis and ureter to delineate the size and patency of the ureter
What is antegrade pyelographyy used to reliably determine?
Presence, degree, and proximal location of ureteral obstruction in cats
What is the preferred modality to confirm uroliths and patency of ureters?
CT with contrast
T/F: Ureteroliths are very easy to manage and remove.
False- they’re literally the worst.
T/F: 20-30% of ureterolith obstructions spontaneously resolve within 3-4 days.
True
What is an important aspect of medical management of ureteral obstruction patients?
Stabilizing uremia
What should be performed if surgery is contraindicated?
Hemodialysis
What should be used if a ureteral obstruction patient is oliguric?
Mannitol
What therapy can help ureteral obstruction patients but hasn’t actually been proven?
Prazosin and amitryptilline therapy- relaxes the ureter and may help the ureteroliths pass easier
Do you want to provide pain management of ureteral obstruction patients?
YES don’t be mean
Is lithotripsy a better choice for dogs or cats?
Dogs
Why is lithotripsy a poor choice for cats?
Stones are often resistant to fragmentation and particles are often too large for the ureter to pass
What is the standard of care for ureteral obstruction?
Surgical placement of a ureteral stent
What is a ureteral stent?
A soft polyurethane fenestrated catheter that has a double pigtail design that are placed inside the entire length of the ureter to keep it patent
How are ureteral stents placed in the dog and the cat?
Dogs- retrograde via cystoscopy
Cats- Antegrade surgically
What is a subcutaneous ureteral bypass system?
The development of an indwelling ureteral bypass using a combination of locking-loop nephrotomy/cystotomy tubes
What do you look for to help confirm a diagnosis of urethral obstruction?
Enlarged bladder, signs of urinary urgency, difficulty expressing the bladder manually, resistance when attempting to pass a urinary catheter
What is done to initially stabilize a blocked cat?
Heat, fluids, ECG, emergency panel, cystocentesis
Why is an ECG done on blocked animals?
Assess for arrythmias due to electrolyte imbalances (hyperkalemia or hypocalcemia)
What is the treatment for a blocked animal with hyperkalemia?
Fluids to control shock, calcium gluconate, IV insulin, Dextrose, Bicarb
Why do we give a hyperkalemic patient IV insulin?
Insulin stimulates the uptake of potassium and removes it from circulation
Why are hyperkalemic patients given bicarbonate?
Protect/correct metabolic acidosis
What is the most common method to relieve an obstructed cat?
Retrograde (typically via catheterization)
What are some other methods to relieve an obstruction?
Penile massage, cystocentesis, penile extrusion, rectal massage of urethra
What should be considered when trying to pass a urinary catheter in a male cat?
Straightening of the urethra/penis
What should be monitored in the ongoing management of a blocked patient?
Urine production and output
What is the ideal way to manage a blocked cat after the obstruction is removed?
Indwelling catheter with pain managment and anti-spasmostics with regular bloodwork
Why are anti-spasmotics useful in managing a blocked cat?
Relaxes urinary system- no real studies but Christie says it helps
What is feli-way?
Pheremones of a momma cat that make your cat more relaxed
What are the most likely causes of urethral rupture in a cat?
Urethral obstruction and traumatic catheterization
What are some common lab abnormalities associated with urethral obstruction?
Hyperkalemia, hyponatremia, acidosis
What are some consequences of a urethral rupture?
Stricture or urethrocutaneous fistula
How do you diagnose a urethral rupture?
Positive contrast retrograde urethrogram
What is the most common etiology of a uroabdomen?
Trauma to the bladder- can happen prior or after manipulation
What is used to confirm uroabdomen?
Creatinine levels of abdominal fluid (should be higher ~2x that of the blood)
Is it appropriate to fix the bladder prior to stabilizing the patient?
No- stabilize patient (fluids etc) prior to surgically fixing the bladder
