Acute phase proteins as biomarkers of urinary tract infection in dairy cows: diagnostic and prognostic accuracy.

The aims of this study were to investigate the level of acute phase proteins in dairy cows with urinary tract infection (UTI) and to evaluate their diagnostic and prognostic value. Eighty-four lactating cows with clinical and laboratory evidence of UTI and 15 healthy controls were included in this study. Serum samples were evaluated for the levels of Haptoglobin (Hp), serum amyloid A (SAA), fibrinogen (Fb), α1-Acid glycoprotein (AGP), total protein, and globulin. The diagnostic and prognostic performance of each parameter was evaluated by estimating the area under receiver operating characteristics curve (AUROC). Escherichia coli and Corynebacterium spp. were the primary bacteria associated with UTI. The levels of serum Hp, SAA, Fb, AGP, total protein, and globulin were significantly higher in UTI cows. Successfully treated cows (n = 51) had lower levels of Hp, SAA, AGP, total protein, and globulin than non-responsive cows. Overall, Hp, SAA, Fb, and AGP showed comparable diagnostic accuracy (AUROC ranged from 0.93 to 0.98). Both Hp and SAA showed high accuracy in predicting treatment response (AUROC > 0.95), whereas Fb level was of no prognostic value (AUROC = 0.48). From this study, acute phase proteins levels can be used as markers for UTI in cows and higher levels of Hp, SAA and AGP are related to poor treatment response.