Page 237 - Problem-Based Feline Medicine

14 – THE CAT WITH INAPPROPRIATE URINATION 229

– Candida species survive poorly at alkaline pH. – Ketoconazole and itraconazole are not very
– Alkalinization therapy has not been very suc- effective because they have limited urinary
cessful. excretion.
– Potassium citrate may be administered at – Fluconazole may be a viable alternative.
50–75 mg/kg PO q 12 h. – This imidazole is smaller, more water soluble,
– Sodium bicarbonate may also be used at 12 and less protein bound than other commonly
mg/kg PO q 8 h. used imidazoles.
– Active fluconazole is excreted primarily in urine.
More aggressive treatment is warranted in patients that
– Use a dosage of 50–100 mg/cat PO with food.
have symptomatic fungal urinary tract infections.
● Intravesicular clotrimazole
● An attempt should be made to correct predispos-
– Instillation of 1% clotrimazole intravesicularly
ing risk factors.
has been successful in treating fungal cystitis.
● Antifungal drugs should also be used.
– Instillation can be accomplished by anesthesia or
– Flucytosine has a narrow range of antifungal
sedation and urinary catheterization or by cysto-
activity, limited primarily to yeast-like fungi
centesis.
such as Candida, Torulopsis and Cryptococcus.
– Three to four treatments may be necessary.
– Flucytosine is deaminated to 5-fluorouracil in
fungal cells which interrupts intracellular pro-
tein synthesis resulting in death of the cell. Prognosis
– Flucytosine is excreted largely unchanged in
Prognosis for asymptomatic funguria in cats is
urine which makes it a good first-line treatment.
unknown.
– Dosage is 200 mg/kg/day PO divided into three
● Funguria may spontaneously resolve.
or four sub-doses.
● Funguria may also progress to symptomatic infec-
– Resistance may occur.
tion or to bezoar formation.
– Flucytosine should be continued 2–3 weeks
● Some animals may have persistent asymptomatic
beyond clinical resolution of fungal urinary
funguria without discernible harm.
tract infection.
● Amphotericin-B is also effective in the treatment Symptomatic funguria carries a variable prognosis.
of fungal urinary tract infection and can be used ● If systemic fungal infection is present, prognosis
with flucytosine or an imidazole. is guarded.
– Occurrence of nephrotoxicity is a major disad- ● If fungi are limited to the lower urinary tract, the
vantage to its use. prognosis is fair; however, complete clearance of
– Amphotericin-B disrupts fungal cell membranes the fungal urinary tract infection may be diffi-
making it effective. cult.
– Resistance is uncommon.
Bezoar formation may require surgical removal if it
– Dosage is 0.1–0.25 mg/kg IV (administered in
causes urethral obstruction or persistent or recurrent
30 ml of 5% dextrose in water over 15 min) q
funguria, and it cannot be disrupted by medical means.
48 h for up to 6 weeks. It may be also given sub-
cutaneously (see page 26, The Cat With Signs
of Chronic Nasal Disease). Prevention
– Amphotericin B may also be administered by irri-
Because fungal urinary tract infection usually occurs as
gation into the urinary bladder.
a result of a problem with local or systemic host
– A concentration of 200 mg of amphotericin-B
defenses, identification and correction of risk factors
per liter of sterile water is recommended.
may prevent it from occurring.
– This solution is infused at 5–10 ml/kg into the
urinary bladder lumen daily for 5–15 days. Urine from cats with indwelling urinary catheters should
● Imidazole derivatives may be used as treatment be examined periodically, particularly if the animal is
for funguria. receiving antibiotics or immunosuppressive therapy.