Retrospective survey of endoparasitism identified in feces of client-owned dogs in North America from 2007 through 2018.

Our main study objective was to determine the prevalence and trend of parasitic infection in client-owned dogs examined at the veterinary parasitology diagnostic laboratory of Oklahoma State University over the past 12 years. All results of centrifugal flotation, saline direct smear, sedimentation, Baermann, acid-fast staining for Cryptosporidium detection, and Giardia antigen examinations on fecal samples from client-owned dogs submitted to the Boren Veterinary Medical Hospital and Oklahoma Animal Disease Diagnostic Laboratory of Oklahoma State University from 2007 through 2018 were included. The impact of sex, age, and seasonality on the prevalence of parasitic infection was also statistically evaluated. A total of 7,409 cases were included for this study. Majority of cases (79.58%; 5,896/7,409) did not include any parasites, eggs, larva, oocysts, or cysts. Approximately 15.41% (1,142/7,409) of client-owned dogs were infected by at least one parasite, and 5.01% (371/7,409) of dogs were infected by multiple parasites. The most common parasite stage observed was Ancylostoma eggs (8.23%; 610/7,409), followed by Cystoisospora oocysts (5.02%; 372/7,409), Giardia cysts/antigen (4.06%; 301/7,409), Trichuris vulpis eggs (2.74%; 203/7,409), Toxocara canis eggs (2.54%; 188/7,409), Dipylidium caninum proglottids/egg packets (0.84%; 62/7,409), taeniid proglottids/eggs (0.47%; 35/7,409), Sarcocystis sporocysts (0.38%; 28/7,409), Cryptosporidium oocysts (0.30%; 22/7,409), Strongyloides stercoralis larvae (0.20%; 15/7,409), Alaria eggs (0.19%; 14/7,409), Toxascaris leonina eggs (0.18%; 13/7,409), Capillaria eggs (0.16%; 12/7,409), Hammondia-like small coccidian oocysts (0.16%; 12/7,409), Uncinaria stenocephala eggs (0.13%; 10/7,409), Spirometra eggs (0.09%; 7/7,409), Physaloptera eggs (0.09%; 7/7,409), Heterobilharzia americana eggs (0.08%; 6/7,409), Nanophyetus salmincola eggs (0.08%; 6/7,409), trichomonads (0.08%; 6/7,409), Mesocestoides proglottids/eggs (0.05%; 4/7,409), Baylisascaris eggs (0.01%; 1/7,409), Macracanthorhynchus eggs (0.01%; 1/7,409), and Paragonimus kellicotti eggs (0.01%; 1/7,409). In addition to endoparasites, some ectoparasites, such as Demodex mites (0.22%; 16/7,409), Otodectes cynotis mites (0.01%; 1/7,409), Rhipicephalus sanguineus ticks (0.01%; 1/7,409), and Sarcoptes scabiei mites (0.01%; 1/7,409), were detected by fecal examinations. Pseudo/spurious parasites were identified in approximately 4.35% of cases (322/7,409). There was no statistically significant difference for parasite prevalence between sexes (p = 0.3231). However, statistically significant differences were observed with certain parasites when compared by age groups, and generally, prevalence of parasitism decreased as age of client-owned dogs increased (p < 0.0001). Statistical analyses also revealed significant differences by months (p = 0.0013). Overall, the prevalence of parasitic infection in client-owned dogs decreased over the past 12 years (p < 0.0001).