Cats are considered resistant to bacterial infections of the lower urinary tract. Positive cultures of urine are present in 1% of healthy cats and in 1-3% of cats with signs of lower urinary tract disease. In older cats with concurrent illnesses, such as chronic kidney disease (CKD), diabetes mellitus, and hyperthyroidism, surveys show a much larger number of bacterial urinary tract infections (UTI). Up to one-third of older cats with comorbidities may have a positive urine culture (PUC). While younger cats with lower urinary tract disease demonstrate overt clinical signs (hematuria, stranguria, and pollakiuria), UTI in older cats with concurrent diseases are frequently asymptomatic or occult.
In this study, investigators performed routine urine cultures in 25 cats with CKD to assess the overall prevalence and clinic signs associated with a PUC. An occult UTI was defined as a PUC not associated with clinical signs of lower urinary tract disease or pyelonephritis. The study found 31 PUCs from the 25 cats. Eighty-seven percent of PUCs were associated with active urine sediments. The most frequently cultured pathogen was E. coli. Eighteen of 25 cats had occult UTIs. The results also found a significant increased risk of an occult UTI in female cats. This greater risk of bacteriuria in female cats may be due to anatomical features, such as a shorter urethral length, although the exact cause for this susceptibility remains unproven. There was also no association between cats with occult PUC, even when treated, and disease severity or survival. However, creatinine concentration was significantly associated with survival for the first 200 days after study enrolment. [VT]
See also: Eggertsdottir AV, Saevik BK, Halvorsen I and Sorum H. Occurrence of occult bacteriuria in healthy cats. J Feline Med Surg. 2011; 13: 800-3.