Overview

• Infecting fungi/yeasts are usually normal commensal flora of the skin and mucosa, or environmentally ubiquitous organisms.
• Candida albicans is the most common fungal isolate; other Candida spp. are less common, and non-Candida spp. fungi are least common.
• Urinary shedding of fungal organism may occur with systemic fungal infections that have disseminated to the kidneys. This appears to be common in dogs with systemic Aspergillus spp. infection, and cats with Cryptococcus neoformans.
• Organ system affected: renal/urologic.
• Uncommon in dogs and cats.

Signalment

• Dog and cat
• No breed, age, or sex predilection

Signs

• Typical signs of lower urinary tract disease: dysuria and pollakiuria; gross hematuria is rare.
• Many animals are asymptomatic.

Causes & Risk Factors

Suspected risk factors: diabetes mellitus, urinary tract stomata (e.g., perineal urethrostomy, cystotomy tubes, indwelling urinary catheters), lower urinary tract disease (e.g., bladder transitional cell carcinoma, chronic bacterial urinary tract infection), recent or chronic antibiotic or glucocorticoid administration.

Differential Diagnosis

• Isolated fungal lower urinary tract infections must be differentiated from systemic infections with secondary appearance of fungi in the urine.
• Lower urinary tract fungal infections may rarely progress to pyelonephritis.
• Contamination of urine samples during collection may occur in animals with cutaneous or mucocutaneous yeast overgrowth (i.e., ventral abdominal or perivulvar dermatitis or balanoposthitis).

CBC/Biochemistry/Urinalysis

• CBC and biochemistry usually unremarkable. If infection has ascended to the upper urinary tract or has systemically disseminated then abnormalities will reflect those organs involved.
• Yeast/fungi may be visible within urine sediment. However, low numbers of organisms may necessitate concentrated sediment preparations for visualization.
• Fungal species cannot be determined solely based oncytologic appearance.

Imaging

N/A

Diagnostic Procedures

Drug(s)

• Oral fluconazole (5–10 mg/kg PO q12h) is the initial treatment of choice.
• Itraconazole or ketoconazole may be effective in some patients, but are not recommended because of poor urinary excretion of active drug.
• In patients with persistent infection despite 4–8 weeks of fluconazole, intravesicular (bladder) infusion of 1% clotrimazole (1% solution in PEG 400) may be considered.
• Intravesicular 1% clotrimazole infusion protocol: catheterize and empty the bladder. Infuse 7.5–10 mL/kg of 1% clotrimazole solution (volume should be determined by bladder palpation during infusion). Infused fluid should be retained for a minimum of 15–30 minutes; most cats will retain the infused drug if not allowed access to a litter box or urination area, whereas in dogs, balloon catheters may be required to prevent premature voiding. Repeat infusion q7 days for a minimum of three treatments. Repeat fungal urine culture approximately 1 week after third treatment to determine whether additional infusions are required. Oral fluconazole therapy should be continued throughout the infusion protocol.
• Amphotericin B (intravenous or intravesicular) treatment has been attempted in sporadic cases, but efficacy is unknown.
• Benign neglect and regular monitoring may be considered in asymptomatic patients with persistent infections despite repeated treatment attempts. However, ascending infection (i.e., fungal pyelonephritis) and systemic dissemination may occur.

Contraindications/Possible Interactions

• Intravesicular clotrimazole appears to be safe but has not been fully investigated.
• Intravesicular clotrimazole should be avoided in animals with recent bladder surgery or urethral trauma.

Associated Conditions

• Diabetes mellitus
• Transitional cell carcinoma

See Also

• Aspergillosis chapters
• Cryptococcosis