Abstract
Background:
Urethral catheterization in the critical care unit often compromises the urinary tract’s defense mechanisms of canine patients and potentially leads to hospital-acquired systemic infection. Clinical signs of hospital-acquired catheter-associated urinary tract infections (CAUTIs) are frequently absent in critical dogs.

Aim:
This study aimed to evaluate the correlation between urinalysis results and CAUTIs in critical care unit dogs and assess the impact of prior antibiotic treatment for underlying diseases and antibiotic-resistant bacteria.

Methods:
Twenty-eight dogs underwent urethral catheterization in the critical care unit of Kasetsart University Veterinary Teaching Hospital. Bacterial cultures and drug sensitivity tests were performed immediately after catheter placement (day 0), 3, and 7 and before removal. A positive urine culture was defined as ≥104 CFU/mL. Urinalysis parameters included urine pH, urinary specific gravity (USG), proteinuria, bacteriuria, pyuria, and hematuria. Only dogs with culture-negative results on day 0 were included. Data were analyzed using GraphPad Prism version 10.0.2. Kaplan-Meier survival analysis was used to assess the probability of being free from CAUTIs over time.

Results:
No significant association was observed between urine cultures and urinalysis parameters, catheterization duration, breed, sex, neutering status, or age. Dogs pretreated with antibiotics exhibited CAUTI-free periods longer than previously reported. Kaplan-Meier analysis showed that CAUTI-free probabilities were 92.8% at 3 days, declining to 60.7% by 7 days and 53.6% at 10 days. Alarmingly, 80% of the isolates (12/15) were multidrug resistant organisms (MDRO) organisms resistant to ≥3 antimicrobials. A high incidence of hospital-acquired CAUTIs was detected in 13 out of 28 cases (46.4%). The dogs with CAUTIs stayed longer in the hospital than the dogs without CAUTIs.

Conclusion:
Routine urinalysis is unreliable for predicting hospital-acquired CAUTIs. The high rate of MDRO among critical care dogs underscores the urgent need for judicious antibiotic use and the need for enhanced diagnostic methods in critical care settings. This study proposes that serial bacterial cultures combined with modified urine sediment examinations can better manage CAUTI detection and reduce the growth of MDROs in veterinary practice.

Key words: Hospital-acquired infection, Catheter-associated urinary tract infection, Urinalysis, Canine patients, Critical care unit