A new open-access study in the Journal of Veterinary Internal Medicine suggests that subclinical bacteriuria in cats with chronic kidney disease may not warrant routine antimicrobial treatment, adding useful evidence for GP vets managing a common and often uncomfortable grey area.
Method
The multicentre retrospective study reviewed records from 287 client-owned cats with chronic kidney disease. Cats were included if they had CKD, a urine culture obtained by cystocentesis, and no signs of lower urinary tract disease at the time of sampling.
The researchers compared cats with subclinical bacteriuria (109 cats) — bacteria detected on culture without urinary signs — with culture-negative controls (178 cats). They then looked at survival, CKD progression, recurrence or persistence of bacteriuria, and whether antimicrobial treatment appeared to affect outcomes.
Results
Bacteriuria was not significantly associated with survival. CKD progression was also similar between groups: 42% of cats with subclinical bacteriuria progressed over 12 months compared with 40% of controls. However, low body condition score and higher creatinine were associated with reduced survival.
Bacteriuria was not significantly associated with survival. CKD progression was also similar between groups
Antibiotics were prescribed to 85 of 109 cats with subclinical bacteriuria, including 35 treated before susceptibility results were available. However, treatment did not reliably prevent later bacteriuria or UTI. Among cats with follow-up data, bacteriuria or UTI was later detected in 52 of 75 cats, and in treated cats, multiple episodes were still found in 62%.
Limitations
This was a retrospective study, not a randomized treatment trial. That means the researchers could identify associations, but they could not fully control how cats were investigated, treated, or followed up.
Follow-up was also incomplete. Many cats were lost to follow-up or alive at the study endpoint, meaning only a minority of the full cohort contributed to the survival analysis. Urine cultures were not performed as part of a standardized screening protocol, which could introduce selection bias, and diagnostic and treatment protocols differed between hospitals.
Another important caveat is that chronic pyelonephritis could not be definitively ruled out in every case. So, while the findings support antimicrobial restraint in stable CKD cats with positive urine cultures but no urinary signs, they should not replace clinical judgement in cats with systemic illness, worsening renal parameters, or other evidence of upper urinary tract disease.
Bottom line for practice teams
For GP vets, the practical message is "do not automatically treat an asymptomatic CKD cat just because bacteria are cultured from urine".
For GP vets, the practical message is "do not automatically treat an asymptomatic CKD cat just because bacteria are cultured from urine". The paper supports a more cautious approach: check carefully for lower urinary tract signs, systemic illness, evidence of pyelonephritis, and changing renal parameters; use culture and susceptibility when treatment is clinically indicated; and monitor closely when withholding antimicrobials.
