Trends in canine GI parasitism
Emerging data from a recent study reveal that the frequent misidentification of spurious parasites in canine feces may signal an elevated risk of true parasitism, emphasizing the importance of accurate fecal diagnostics.
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At the annual WVC conference in Las Vegas, Yoko Nagamori presented a session based on findings from a preprint study she led—Prevalence of spurious parasites identified in feces of dogs and correlation with true canine parasitism—which offers potential insights on canine gastrointestinal parasitism and its diagnostic challenges.1
The study, conducted at Zoetis Reference Laboratories in Louisville, Kentucky, retrospectively analyzed 48,509 fecal samples collected from client-owned dogs throughout 2023. Its primary aim was to differentiate between true parasitic infections and spurious parasite findings—artifacts that can mimic true infection but do not require treatment. According to the study’s findings, true canine parasites were identified in 12.3% of the samples (5,953/48,509), while spurious parasites were detected in 4.8% (2,346/48,509). Notably, Eimeria oocysts accounted for the majority of spurious findings, being present in 4.14% of all samples. The predominance of Eimeria among spurious parasites is relevant given its frequent misidentification during routine fecal examinations, which can lead to misdiagnosis and inappropriate treatment decisions.2
The study also discussed the statistically significant correlation between the presence of spurious parasites and true parasitic infections (P < 0.0001). This finding may suggest that dogs excreting spurious parasites are at an elevated risk of harboring true parasitic infections, potentially because of shared exposure factors such as coprophagic, predatory, or scavenging behaviors. The study’s findings further revealed that canines under 12 months exhibited a higher prevalence of spurious parasites, a trend that was mirrored in the occurrence of true parasitic infections. In addition, the data showed that intact female dogs had the highest rate of spurious parasite detection when compared with other sex/reproductive groups.2
Seasonal trends also emerged from the analysis. The prevalence of spurious parasites peaked in February, while true parasitic infections reached their highest levels in January. These seasonal variations may be related to increased environmental contamination and changes in canine behavior during the colder months, as well as to the breeding patterns of various animal species that serve as definitive hosts for parasites like Eimeria, according to the study.2
The study addressed the practical implications of these findings for everyday veterinary practice, including the importance of proper fecal sample collection techniques—ideally, collecting 3 to 5 g of fresh fecal matter immediately after defecation—and for performing examinations promptly or storing samples under refrigeration if delays are unavoidable. By doing so, practitioners can enhance the sensitivity of fecal examinations and better differentiate between spurious and true parasitic infections, the study implies.2
The study concluded with a call to action to integrate these diagnostic insights into routine practice. By recognizing the significance of spurious parasites as potential indicators of environmental exposure and increased risk for true parasitism, clinicians can refine their diagnostic approaches and with the goal of improving patient care.2
References
- Nagamori Y, Warren Z, Houma M, et al. "Prevalence of spurious parasites identified in feces of dogs and correlation with true canine parasitism." SSRN. Published 2023. doi:10.2139/ssrn.5141670
- Nagamori Y. Are you seeing the GI parasites that are seeing you? Emerging prevalence data. Presented at: WVC; Las Vegas, Nevada. March 2-5, 2025.
