Page 191 - Problem-Based Feline Medicine

11 – THE CAT STRAINING TO URINATE 183

– Decompress the bladder by cystocentesis ● Hypokalemia may occur with prolonged diuresis or
using a 23 G × 32 mm (1.25 in) needle attached the use of potassium-free fluids. Potassium sup-
to an extension tube, a 2-way valve and 50 ml plementation can be given in intravenous fluids
syringe. Removal of approximately 30 ml of (0.5 mmol/kg/h) or orally (2–6 mmol/cat/day) until
urine from the bladder may trigger sponta- the cat starts eating.
neous micturition. The bladder should not be ● The gluconate form of potassium is preferred
manually palpated for the next 24 hours. orally.
– Consider cystotomy with placement of an ● Once the cat voluntarily eats and drinks, the fluid
indwelling catheter (Foley catheter, 8 French; rate is decreased over 24 hours while hydration sta-
Stamey suprapubic catheter, 10 French) in the tus is monitored.
urinary bladder, and percutaneous prepubic uri-
Prevention.
nary drainage or a perineal urethrostomy.
● Feed exclusively a specially formulated non-cal-
– Perineal urethrostomy is only recommended
cinogenic diet to minimize struvite crystal forma-
as a last resort because it does not prevent
tion and maintain a low urine pH (<6.5) and low
reoccurrence of non-obstructed disease and it
specific gravity (<1.030, ideally 1.020). Meat- or
can predispose to ascending urinary tract
fish-flavored liquid or water can be added to
infection, urine scald dermatitis and urethral
increase water intake.
stricture.
– Canned food produces a lower urine specific
– Perineal urethrostomy is recommended if fre-
gravity than dry food, and decreases the fre-
quent urethral obstruction occurs despite ade-
quency of recurrence in cats. If feeding dry food,
quate medical management or urethral
add 1 cup of water per 1 cup of diet and allow to
lesions exist that cause recurrent or persistent
soak at least 5 minutes before feeding.
obstruction.
Prednisolone (2.5 mg/cat orally every 12 hours for 3–5 Prognosis
days) may reduce urethral inflammation but may pre-
The prognosis depends on the duration of the obstruc-
dispose to urinary tract infection.
tion, on the ease of obtaining and maintaining urethral
Functional urethral obstruction due to urethral irrita- patency, and correction of renal failure.
tion and inflammation resulting in urethral spasm can Prognosis is grave if:
occur following mechanical obstruction. This is diffi- ● The duration of the obstruction is more than 60
cult to differentiate from mechanical urethral obstruc- hours.
tion, however, failure to encounter obstructing material ● The packed cell volume of centrifuged bloody
or a grating sensation during recatheterization, suggests urine is greater than 2%.
function urethral obstruction. ● Urinary specific gravity is below 1.020.
Phenoxybenzamine (5 mg/cat orally daily for 3–5 days) The recurrence rate is 35–50%, mainly within 6
may help reduce urethral outflow resistance. months after hospitalization. Recurrence appears to be
Bladder atony may occur due to overdistention and can higher in cats under 4 years of age.
be corrected (see The Incontinent Cat). Studies on the efficacy of specially formulated diets in
naturally occurring idiopathic LUTD are limited but the
Postobstructive diuresis.
results are encouraging. Such diets have been formu-
● Following relief of the obstruction, a marked
lated to reduce magnesium and phosphate intake and
diuresis may occur and last for 2–10 days.
promote a dilute, acid urine. However, the pH of these
● Intravenous fluid therapy is required to maintain
diets may predispose to oxalte uroliths in susceptible
hydration and electrolyte balance. Initially a dex-
cats.
trose saline solution is used to hydrate the patient
over 4–6 hours, followed by a balanced electrolyte The prognosis following urethrostomy is good in that
solution (lactated Ringers solution) to maintain recurrence of urethral obstruction is unlikely, but
hydration and correct electrolyte imbalance. recurring episodes of non-obstructed cystitis may