Gastrointestinal Nematodiasis in Hoofstock

Chapter 51 Gastrointestinal Nematodiasis in Hoofstock

Species of perissodactylid and artiodactylid ungulates evolved to take advantage of the grasses, shrubs, trees, roots, tubers, and fruits on and below the surface of the land. Similarly, nematode parasites evolved to take advantage of the mucosal surfaces of the ungulates’ gastrointestinal (GI) tracts, to maximize the chances of their eggs and larvae surviving outside the host and infecting a new host.

This chapter examines the problems that occur when the host-parasite balance tips in favor of the nematodes and how we can investigate and control, or live with, the situation.


All hoofstock, especially those with access to grass enclosures, should be assumed to carry a range of GI nematodes. The extent of the infestation, the species of nematodes involved, and the clinical significance should be assessed for each host species.6,7,12

In which climatic region is the ungulate collection? In a temperate zone, nematodes would be expected to thrive in the wet summer but would need to survive a harsh winter as resistant stages in the environment and within some of the hosts. In Mediterranean and semiarid regions, however, the cool, wet winters would favor the nematodes, but they would be suppressed and would need to survive during the hot, dry summers.

What ungulate species are held by the collection? Species generally evolved with the nematodes that survive in the same climatic region and would be expected to be relatively resistant to clinical disease, certainly compared with species from different climates. In the temperate climate of the United Kingdom, species of deer such as red deer (Cervus elaphus) show little clinical effects of nematodiasis unless circumstances favor the nematodes (see later discussion). However, antelope such as scimitar-horned oryx (Oryx dammah) and addax (Addax nasomaculatus), from semiarid and arid regions, and musk ox (Ovibos moschatus), from the tundra, are highly susceptible.

What do the clinical and necropsy records reveal? Even when no specific parasite monitoring has been done, the general records for the collection should still have much useful information. How long have species of interest been in a particular enclosure? How has the herd size and stocking density changed over time? Have there been reports of poor body condition, diarrhea, or deaths in the group? Are there fecal egg count results on file?


Primary Disease

Under certain situations, GI nematodes may cause clinical disease without other pathologic agents. Examples include the following:

Trichuriasis has been shown to cause colitis in camels (Camelus spp.)5 and often infects giraffe (Giraffa camelopardalis).

Ascariasis has been responsible for the death of zebra foals, usually from blockage of the intestines by large accumulations of adult Parascaris equorum.10 Another ascarid, Toxocara vitulorum, is transmitted in the colostrum from cattle to calves and may be pathogenic in neonatal European bison (Bison bonasus).

In many cases, more than one species of nematode may be found, or nematodes and other parasites are found together, and it may be impossible to decide which species is the main pathogen. For example, a mixed infection with a Trichuris sp. and several Eimeria coccidial spp. was thought to be responsible for diarrhea in a 10-day-old red lechwe calf (Kobus leche leche).3

Secondary Disease Factors

Secondary disease caused by GI nematodiasis is probably more common than primary disease and likely underreported. In these cases, many pathologic processes may be causing loss of body condition, weakness, and death, and the relative importance of each factor may be difficult to determine. Common factors in secondary disease include climate, malnutrition, stress, physiologic state, and concurrent disease.

Oct 1, 2016 | Posted by in EXOTIC, WILD, ZOO | Comments Off on Gastrointestinal Nematodiasis in Hoofstock
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