ID07 - Combining Syndromic PCR with Routine Fecal Screening Increases Enteropathogen Detection in Diarrheic Dogs and Cats

Abstract: Background– In dogs and cats presenting with diarrhea and systemic illness, infectious causes should be ruled out before pursuing invasive diagnostics such as endoscopy or biopsy. Hypothesis/Objective– In diarrheic patients initially screened with fecal flotation and fecal antigen testing, adding PCR testing for common enteropathogens increases detection of infectious disease. Animals– 2944 dogs and 1976 cats submitting comprehensive fecal infectious disease testing to IDEXX Reference Laboratories in 2025. Methods– Retrospective results were evaluated for patients tested within seven days by all of the following: fecal flotation (zinc sulfate centrifugation), Giardia antigen immunoassay, IDEXX Fecal Dx™ Antigen Panel, and the Comprehensive Diarrhea RealPCR™ Panel. Flotation and antigen tests can detect Giardia, Cystoisospora, hookworms, roundworms, whipworms, and tapeworms. Canine and feline PCR panels assessed 10 and 7 additional bacterial, viral, toxin, and protozoal pathogens respectively. Giardia PCR, C. perfringens enterotoxin/alpha toxin genes, and feline coronavirus were excluded due to limited clinical relevance. Results– In dogs, fecal parasites were detected in 4.6 % of flotations and 9.2 % of antigen tests. PCR identified one or more additional pathogens in 29.4 % of patients. In cats, parasites were detected in 5.7 % of flotations and 11.5 % of antigen tests, and PCR detected additional pathogens in 11.6 % of patients. Co-infections within and across diagnostic tests were frequently detected. Conclusions and Clinical Importance– Adding syndromic PCR testing to standard fecal parasite testing substantially increases detection of infectious agents associated with diarrhea. Identifying infectious causes early may reduce unnecessary diagnostic procedures for suspected chronic enteropathy.