OPTIMIZING DIAGNOSTIC ACCURACY IN CANINE URINARY TRACT INFECTIONS: FUTURE DIRECTIONS TO REDUCE ANTIMICROBIAL MISUSE IN VETERINARY PRACTICE

The thesis addresses the optimization of diagnostic accuracy in canine urinary tract infections (UTIs), aiming to reduce the inappropriate use of antimicrobials in veterinary clinical practice. Following an epidemiological overview of canine UTIs, the work presents an analysis of the International Society for Companion Animals Infectious Diseases (ISCAID) guidelines, a document that provides the foundation for standardized classification, diagnosis, and treatment of canine and feline UTIs in veterinary medicine. An updated overview is subsequently provided on antimicrobial resistance, the one health approach, and the European and national recommendations regarding antimicrobial choice in veterinary medicine. The main challenges of the diagnostic process for canine UTIs are explored, particularly the low specificity of lower urinary tract signs (LUTS) and the variability in diagnostic accuracy associated with urinary sediment analysis. The thesis highlights the need for accurate biomarkers to support the screening of canine patients with UTIs and reviews the most promising molecules identified in human medical literature. A brief section is dedicated to the clinical relevance of potential point-of-care (POC) tests as rapid diagnostic tools for patients with suspected UTI. In the experimental part, the analysis begins with a ten-year retrospective local study aimed at identifying the main uropathogens involved in canine UTIs and detecting possible trends in antimicrobial resistance by comparing the five years before and after the publication of the ISCAID guidelines (2019). The importance of up-to-date local data to guide general practitioners towards more informed empirical antibiotic use is emphasized. Subsequently, the diagnostic performance of several promising biomarkers for the diagnosis of canine UTI is evaluated, including urinary neutrophil gelatinase-associated lipocalin (uNGAL), urinary interleukins 8 and 6, urinary xanthine oxidase, and urinary myeloperoxidase. Among these, urinary interleukin-8 and urinary xanthine oxidase are identified as the most promising disease markers, highlighting the need for further research, particularly including comparison with subjects affected by subclinical bacteriuria. Finally, the clinical applicability of a POC test for the measurement of uNGAL is assessed, showing almost perfect agreement with the reference ELISA method. Overall, the thesis emphasizes the need to integrate innovative biomarkers, antimicrobial stewardship strategies, and veterinary education in order to improve the management of canine UTIs and reduce antibiotic resistance from a One Health perspective.