Subclinical bacteriuria in cats: prevalence, findings on contemporaneous urinalyses and clinical risk factors

Abstract

Objectives Subclinical bacteriuria (SB) is bacterial colonization of the urinary tract in the absence of clinical signs. The purposes of this study were to determine the prevalence of SB in cats and to describe results of the contemporaneous urinalysis. Secondarily, patient characteristics associated with SB were compared with those for cats without SB. Methods An electronic search identified all urine cultures performed on cats at a teaching hospital between 2009 and 2015. Results were subcategorized based on the presence or absence of lower urinary tract disease (LUTD) and SB-positive cases identified. The first control population was from samples without LUTD. The second control population was from all samples not identified as a SB-positive sample, including subclinical negative samples and those with LUTD. Five controls for each SB-positive sample were selected for both control groups. Medical records for all groups were reviewed. Results In all, 31/500 (6.2%) subclinical samples were positive. Most infections were a single organism (n = 27); four contained multiple organisms. Escherichia coli was the most common species (58%) followed by Enterococcus species (25%). Positive specimens were more likely to be from female cats (n = 24) vs male (n = 7; P = 0.0054). SB was strongly associated with bacteriuria (60% vs 6%; P <0.0001) and pyuria (67% vs 19%; P <0.0001). Positive specimens were significantly more likely to have an abnormal sediment examination (odds ratio 13.5, P <0.0001). When compared with all specimens including those with LUTD, SB was significantly associated with a lower urine specific gravity (1.022 vs 1.030; P = 0.0256) and presence of chronic kidney disease (68% vs 46%; P = 0.0168). Conclusions and relevance In this study, SB appears to be uncommon in cats and, in most cases, is associated with an abnormal urine sediment examination. Based on this study, there is little indication to perform a culture in a cat with no clinical signs of LUTD and an unremarkable sediment examination.

Hyperthyroidism is not a risk factor for subclinical bacteriuria in cats: A prospective cohort study

“…We found females to be at higher risk for developing subclinical bacteriuria than males (OR, 6.9; Table 5), regardless of thyroid status, a finding that is in accord with other studies in cats 26,36 . However, we found that neither age nor age stage posed an increased risk for subclinical bacteriuria, similar to a large study of 179 middle‐aged to elderly cats, 27 but in contrast to others in which older age was a risk factor 26,36 . A possible explanation for these differences could be the selection of middle‐aged to older cats in our study (no cats <7 years of age were included), which likely affected the association between increasing age and subclinical bacteriuria.…”

“…Although azotemia was not predictive of subclinical bacteriuria, evidence of kidney disease in the form of dilute urine specific gravity (<1.035) did increase the risk, similar to findings in some, 5,26,37 but not all studies 6,11,36 . In addition, both pyuria and bacteriuria were predictors for subclinical bacteriuria, similar to findings in other studies 6,11,26 . Although hematuria was common, it was not a predictor for subclinical bacteriuria in our study.…”

“…This finding is in marked contrast to previous retrospective studies that reported a relatively high prevalence of UTI in hyperthyroid cats (12%‐22%), findings that have led to the widespread belief that hyperthyroid cats are at risk for developing subclinical bacteriuria 3,8‐10 . Our findings agree with other recent studies of mixed populations of cats, which failed to identify an increased risk of subclinical bacteriuria in much smaller cohorts of cats with hyperthyroidism 26,27 …”

“…A wide range of prevalence rates for subclinical bacteriuria has been reported in cats, varying from low rates of <1.0%‐3.3%, 12,34,35 to intermediate rates of 6.1, 7.9, and 10%‐13%, 26,27,36 to a high rate of 28.8% 11 . The main difference in these studies was the age of the cats, which tended to be younger in the studies with lower prevalence rates 12,34,35 and older in the studies with prevalence rates >6% 11,26,36 .…”

“…Although hematuria was common, it was not a predictor for subclinical bacteriuria in our study. Because cystitis can lead to the presence RBC in urine sediment, hematuria might be expected in cats with subclinical bacteriuria 3,26 . However, cystocentesis itself can induce transient microscopic hematuria indistinguishable from pathological hematuria, 38,39 and the number of RBCs in the sediment cannot be used as a reliable predictor of a positive urine culture.…”