Cystitis

Owners notice frequent passing of small volumes, straining, painful urination, urinating in inappropriate places and visible blood in the urine. Some animals with bacteriuria show no signs at all. Fever, painful kidneys, lethargy, vomiting and increased thirst and urination point to ascending pyelonephritis, although in cats these signs are often vague. Diagnosis rests on quantitative culture of urine collected by cystocentesis before antimicrobials are given, with growth of at least 1,000 colony-forming units per mL considered significant.

Cystitis is inflammation of the urinary bladder. In its bacterial form, organisms from the perineum and distal urethra ascend into the normally sterile bladder when host defences fail. Those defences include frequent, complete voiding, concentrated urine with antimicrobial properties, normal anatomy and resident flora, an intact urothelial barrier and systemic immunity. Escherichia coli is the leading cause and colonises using adhesins such as type 1 and P fimbriae, iron-acquisition systems and haemolysin; enterococci, streptococci and Staphylococcus felis are also isolated. In cats, bacterial infection explains only 2 to 19% of lower urinary tract signs, and feline idiopathic cystitis, a non-bacterial inflammation, shares the same clinical and urinalysis picture.

Dogs and cats are affected, females more often because of their shorter urethra. Only 1 to 2% of cats develop a urinary tract infection in their lifetime, but frequency rises in cats over 10 years; spayed females and Abyssinians are overrepresented, and most affected cats have concurrent disease such as chronic kidney disease, diabetes mellitus or hyperthyroidism. In dogs, long-term corticosteroids, hyperadrenocorticism, diabetes and kidney disease increase risk. Dilute urine, incontinence, indwelling catheters, perineal urethrostomy and anatomical defects also predispose. Infection is termed recurrent at three or more episodes in 12 months, two or more in 6 months, or one within 3 months of the last, and sporadic otherwise. Bacteria in urine without signs, subclinical bacteriuria, is a separate entity.

Feline idiopathic cystitis shares the signs and urinalysis findings, with haematuria in over 70% and pyuria in up to 77% of affected cats, so quantitative urine culture is needed to separate it. Urolithiasis and bladder neoplasia can present identically. Subclinical bacteriuria has bacteria in urine without lower urinary tract signs. Pyelonephritis adds fever, renal pain and systemic illness.

Urinary bladder, urothelium, urethra; kidneys and upper urinary tract when infection ascends

Correct predisposing factors such as a hooded vulva. ISCAID recommends no preventive treatment; evidence for cranberry extract, probiotics and intravesical products is mainly anecdotal.

Sporadic cases whose signs resolve with empirical treatment need no repeat urine testing (MSD). Recurrence prompts a search for risk factors. Untreated subclinical bacteriuria in older cats was not linked to shorter survival (Dorsch et al.).