Urinary tract infections in culled sows from Greek herds: prevalence and associations between findings of histopathology, bacteriology and urinalysis
Abstract Background Urinary tract infections (UTI) of sows which include cystitis, which may progress to ureteritis and pyelonephritis affect their productivity, longevity and welfare. In this study we determined the prevalence of UTI by histopathology and bacteriology and investigated possible associations between histologically confirmed cystitis and the results of urinalysis and urine cultures in culled sows from three Greek farrow-to-finish herds. Materials and methods Routinely culled sows were included in the study. Their urinary bladders were collected from abattoirs and examined histopathologically. Furthermore, urinalysis and urine cultures were performed on urine samples aseptically collected from the bladders. Results Histologically confirmed cystitis was evident in 85/185 (45.94%) culled sows. Among those, 44 (51.76%) suffered from acute and 41 (48.24%) from chronic inflammation. The majority of the positive urine cultures were due to colonization of the urinary tract with E.coli, which was responsible for 55.81% of the total cases, followed by Staphylococcus spp. which caused 18.60% of the infections detected. Evidence of cystitis was associated with bacteriuria and sows with bacteriuria were 2.30 (p = 0.03, 95% CI: 1.10–4.83) times more likely to have histologically confirmed cystitis compared to sows with negative urine cultures. Bacteriuria was associated with proteinuria (p < 0.01), urine pH (p < 0.01) and presence of sediment (p < 0.01) in urine. Sows with proteinuria had 9.72 (2.63–35.88) times higher odds of bacteriuria than those without. Histologically defined cystitis was associated with proteinuria (p < 0.01) and increased urine pH (p < 0.01). Sows with proteinuria were 5.18 times (2.03–13.2) more likely to have histological lesions consistent with cystitis, than those without. Conclusions In the studied herds, UTI affected almost one out of two culled sows. Bacteriuria, which was more common among sows with UTI than those without, was mainly ascribed to members of the intestinal and environmental microbiota. Proteinuria and the existence of urine sediment which were associated with UTI may be proposed as likely on-farm predictors of UTI in live sows.