Association of fecal sample collection technique and treatment history with Tritrichomonas foetus polymerase chain reaction test results in 1717 cats

BACKGROUND: Fecal polymerase chain reaction (PCR) testing for Tritrichomonas foetus is considered the most sensitive means for diagnosis of infection but results could be influenced by fecal collection technique and prior use of antimicrobial drugs. OBJECTIVES: To establish any association between fecal collection technique or treatment history and results of fecal PCR testing for T. foetus. ANIMALS: Fecal samples from 1717 cats submitted by veterinarians between January 2012 and December 2017. METHODS: This study used a retrospective analysis. T. foetus PCR test results from 1808 fecal samples submitted for diagnostic testing were examined for their association with method of fecal collection and prior antimicrobial treatments. Data were collected from sample submission form. RESULTS: Positive T. foetus PCR test results were obtained for 274 (16%) cats. Fecal samples collected via fecal loop had increased probability of positive PCR test results (odds ratio [OR] 2.04, 95% confidence interval [CI] 1.31‐3.17, P = .002) compared to samples collected by colonic flush. There was no association between PCR test results and treatment history, treatment type, or prior treatment with ronidazole. After an initial positive PCR test, 4/19 (21%; 95% CI 2.7%‐39.4%) cats treated with ronidazole had a second positive test result. CONCLUSIONS AND CLINICAL IMPORTANCE: Results of this study support that fecal samples collected by loop might be better for PCR diagnosis of T. foetus infection. Lack of association of ronidazole with PCR test results and a 21% all‐potential‐causes failure rate of ronidazole in cats with preconfirmed infection are important limitations to use of this drug.