Megan K. Hirano1*, BS; Johanna L. Watson1, DVM, PhD, DACVIM; Bruce Christensen1, DVM, MS, DACT; Robert Farkas2, DVM, PhD, DSc, DEVPC; Waltraut Zimmermann3, PhD; Kristin Brabender3; Rae Gandolf4, DVM, DACZM
There is a paucity of published literature available that addresses gastrointestinal parasite burden in Przewalski’s horses (Equus ferus przewalskii), and it is unknown whether current deworming protocols for Przewalski’s horses are superior to other management systems for minimizing their gastrointestinal parasite load.2 Fecal samples of 145 captive Przewalski’s horses were analyzed using the standard McMaster test to determine selective gastrointestinal parasite burden in eggs per gram between two different management systems. The sampled Przewalski’s horses were managed in either a natural management system (free-ranging, low stocking density and untreated with anthelmintics) in the Hortobágy National Park, Hungary (n=126) or in a traditional management system (separate smaller pastures and treated quarterly by weight with rotating oral anthelmintics) in The Wilds, Ohio (n=19). Results of the McMaster test for the two populations were analyzed and results showed species from the family Strongylidae as the primary helminth in both populations. No Parascaris equorum eggs were observed in either population. Three horses that died or were humanely euthanized during the study at Hortobágy National Park were necropsied to confirm the lack of other parasite species on gross and histologic evaluation. The Przewalski’s horses in the natural system had a significantly lower gastrointestinal parasite burden than those in the traditional system (1,142±77.77 versus 1,968±268.30 eggs per gram, respectively; p<0.001). Perhaps, given enough acreage, coexistence between Przewalski’s horses and parasites is superior to, or as effective at, controlling parasite-induced health problems as regularly treating with anthelmintics.1,3
The authors thank Dr. Waltraut Zimmermann and Kristin Brabender from the Hortobagy National Park for their resources and generous hospitality. We would also like to thank Dr. Brian Hampson for his assistance and formalin contribution to the necropsies. We would like to thank Dr. Rae Gandolf at The Wilds for her resources and generous hospitality. We would also like to thank the STAR Program and International Programs for funding a major portion of the project.
1. Cross PC, Drewe J, Patrek V, Pearce G, Samuel MD, Delahay RJ. In: Delahay RJ, Smith GC, Hutchings MR (eds.). Wildlife Population Structure and Parasite Transmission: Implications for Disease Management. Springer: Japan; 2009.
2. Slivinska K. The gastro-intestinal parasites community of the Przewalski's horse, Equus przewalskii Poljakov, 1881, and the domestic horse in the Chernobyl exclusion zone. Wiad Parazytol. 2006;52:55–58.
3. Thamsborg SM, Jorgensen RJ, Waller PJ, Nansen P. The influence of stocking rate on gastrointestinal nematode infections of sheep over a 2-year grazing period. Vet Parasitol. 1996;67:207–224.