Performance of the Vetscan Imagyst in point-of-care detection of <i>Giardia duodenalis</i> in canine fecal samples

<i>Giardia duodenalis</i> is a common parasite of the gastrointestinal tract of dogs, with an especially high prevalence in dogs <1-y-old. Methods for detecting <i>G. duodenalis</i> are point-of-care (POC) tests such as lateral-flow tests or fecal flotation. The Vetscan Imagyst (Zoetis) is a new POC device for the detection of <i>G. duodenalis</i> in fecal samples using zinc sulfate flotation, automated slide scanning, and image recognition with artificial intelligence. Vetscan results are the number of <i>Giardia</i> cysts per coverslip. We compared the performance of the Vetscan and another POC test (SNAP <i>Giardia</i> test; Idexx) with a direct immunofluorescence assay (IFA) performed in a specialized parasitology laboratory as the reference test. We included 164 dogs <19-mo-old. We used pooled fecal samples from 3 defecations gained within 2-3 d and tested the repeatability of the Vetscan by triplicate measurement. Compared to IFA, Vetscan had a diagnostic sensitivity of 88.4% and specificity of 98.1%; SNAP had a diagnostic sensitivity of 74.4% and specificity of 98.1%. A variation coefficient of 67.0% was determined for the Vetscan results. The performance of the Vetscan is acceptable for the qualitative evaluation of fecal samples (<i>Giardia</i> positive or negative), and the device can be used by untrained personnel. Given its high variation coefficient, we do not recommend the Vetscan for monitoring the number of cysts.