Prevalence of Enteropathogens in Dogs Attending 3 Regional Dog Parks in Northern California

Hascall, K.L.; Kass, P.H.; Saksen, J.; Ahlmann, A.; Scorza, A.V.; Lappin, M.R.; Marks, S.L.

The paradoxical results of intestinal parasites being detected significantly more frequently in dogs that had been dewormed compared to dogs that had not been dewormed within the past 6 months were likely a reflection of the type of intestinal parasites most commonly detected. Only 1 of the infected dogs that was dewormed was diagnosed with Ancylostoma caninum, whereas all of the other dogs that were dewormed were infected with parasites (Giardia spp., Cryptosporidium spp., Trichuris vulpis, and Cystoisospora spp.) that are not susceptible to commonly administered deworming medications such as pyrantel pamoate. The differences in detection of Giardia cysts on fecal flotation between the commercial reference and university laboratories could have been associated with known differences in methods for fecal flotation between the 2 laboratories. The commercial laboratory performed a single centrifugation flotation, and technicians scanned the slide at 109 magnification for approximately 60-120 seconds. In contrast, a single parasitologist with over 30 years experience performed all of the flotations at the university laboratory utilizing a double centrifugation flotation technique with evaluation of approximately 50 random high-power fields to determine the average number of cysts, oocysts, or ova per hpf. Interestingly, there were no significant differences between the 2 laboratories in regard to any other parasites detected on fecal flotation. This might be because nematode ova are more readily recognized on a slide because of their size compared to Giardia cysts. These results emphasize that if veterinarians recognize discordant results from different laboratories by similar assays, the laboratories supplying the assays should be alerted to allow for internal investigation into quality assurance.