Urinary tract infections in sows in Italy: accuracy of urinalysis and urine culture against histological findings.

In order to investigate the prevalence of urinary tract infections (UTI) in sow, lower urinary tract (LUT), kidney and urine samples were collected at slaughterhouse from 65 multiparous culled sows. Histopathology was performed on urethra, urinary bladder and -kidney sections. Urine collected by cystocentesis was analysed for physical and biochemical parameters, in addition to microscopic examination of the sediment and quantitative culture ( > 10(5) CFU/ml urine). The diagnostic accuracy of urinalysis and urine culture was calculated for the parameters that correlated with histological diagnosis: bilateral chronic lesions were found in 54 per cent of kidney samples and diffuse/multifocal lymphoplasmacytic infiltration of the submucosa in 53 per cent of the bladder and 68 per cent of the urethra samples. In 49 per cent of cases, the co-occurrence of bladder and urethra lesions was statistically significant (P < 0.009). Turbid urine (80 per cent sensitivity, 50 per cent specificity),  > 5 white blood cells per high-power field (34 per cent sensitivity, 90 per cent specificity), intracellular or free bacteria (43 per cent sensitivity, 90 per cent specificity), and urine culture (49 per cent sensitivity, 97 per cent specificity) correlated with a finding of histopathological changes in the bladder. UTI appears to be common in culled sows in northern Italy. Compared with histopathology, urinalysis and urine culture showed low sensitivity but high specificity in detecting UTI.