Abstract
Haemonchus contortus is a trichostrongyle parasite of ruminants that causes significant disease secondary to red blood cell loss, body protein loss, and chronic inflammation of the abomasum. This parasite is ubiquitous in the United States and presents a significant problem for susceptible animals in the southern United States where a year-round temperate climate allows the parasite to remain viable on pastures.3 H. contortus has been a significant source of morbidity in collections of captive exotic artiodactyls, causing ill thrift, weight loss, anemia, hypoproteinemia, and death.2,5,6 Some species of artiodactyls have been reported to be extremely susceptible to clinical disease caused by this parasite, including giraffe (Giraffa camelopardalis) (R. Ball, DVM, 2000, pers. comm.), sable antelope (Hippotragus niger),6 roan antelope (Hippotragus equinus),4 blackbuck (Antilope cervicapra),6 gemsbok (Oryx gazella gazella) (J. Allen, DVM, 2000, pers. comm.), and Mhorr gazelle (Gazella dama mhorr) (Disney’s Animal Kingdom, unpublished data).
Haemonchus develops resistance to anthelmintic agents readily and can develop resistance to multiple classes of deworming agents simultaneously.3,7 Resistance to the benzimidazole anthelmintics has been well documented.5,7 Current recommendations to minimize the onset of resistance in H. contortus include pasture rotation, infrequent use of anthelmintics, simultaneous use of multiple anthelmintics, and direct oral or injected administration of deworming agents. Implementation of these recommendations may not be possible in all animal management programs.
Copper oxide wire particles (COWP) have been reported to be 96% effective in reducing populations of Haemonchus contortus in sheep.1 The mechanism of action is presumed to be a local toxic effect within the abomasum. Four male antelope were treated with boluses containing COWP (Copasure, Animax Ltd., Columbus, OH, USA) and monitored for 1 yr. The study animals were selected from herds of animals believed to be susceptible to infection with H. contortus and included: one sable antelope (25 g COWP), two gemsbok (12.5 g COWP each), and one scimitar-horned oryx (Oryx dammah) (12.5 g COWP). Fecal egg counts were performed monthly and compared to the egg counts of animals treated with conventional deworming agents.
One treated gemsbok sustained a femoral fracture and was euthanatized 8 mo into the study. No COWP were found at any point within the gastrointestinal tract, suggesting that the particles may be completely broken down or excreted within 8 mo of administration. No Haemonchus were identified within the abomasum grossly or upon microscopic examination and no changes suggestive of copper toxicosis were noted.
There was no statistically significant difference in fecal egg count numbers from animals treated with conventional dewormers and the animals treated with COWP (p>0.05), indicating that within this limited treatment group COWP appear to be as effective as conventional anthelmintic agents in controlling infection with Haemonchus contortus. The effects of gender and season on parasite numbers were not evaluated in this preliminary study.
Doses of copper oxide wire particles recommended by the manufacturer are provided below.
Animals 25–40 kg body weight receive 1x2 g.
Animals 40–70 kg body weight receive 1x4 g.
Animals 70–225 kg body weight receive 1x12.5 g.
Animals 225 kg and over receive 1x25 g.
Literature Cited
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