Efficacy of Ivermectin Against Nematodes Infecting Field Populations of Snowshoe Hares (Lepus Americanus) in Yukon, Canada

Abstract

From July 1990 to February 1991, nematode numbers in free-ranging snowshoe hares (Lepus americanus) at Kluane Lake, southwestern Yukon, Canada, were manipulated by subcutaneous injection (0.4 mg/kg) of ivermectin. Three field experiments were conducted to determine the degree of helminth loss associated with a single administration of ivermectin; the length of time that ivermectin was effective in reducing worm numbers; and the effect of repeated ivermectin administration in reducing worm numbers. Numbers of the nematodes, Protostrongylus boughtoni and Nematodirus triangularis were reduced by approximately 80% 2 wk after treatment with a single dose of ivermectin, and were still significantly lower than controls at 4 wk. However, beyond 2 wk, ivermectin did not affect the rate of acquisition of new worms of either species. All treated groups contained one or more hares in which numbers of P. boughtoni and N. triangularis were not reduced. In addition, ivermectin had no effect on numbers of Trichuris leporis or Passalurus sp. Overall, ivermectin was not as effective against the nematodes of free-ranging hares as has been reported for nematodes of domestic and laboratory animals.

The Efficacy of Anthelmintic Drugs Against Nematodes Infecting Free-Ranging Eastern Grey Kangaroos, Macropus Giganteus

“…There may be differences in the activity of the anthelmintics against adult strongyles and immature larvae, especially those inhibited within the tissues, although the propensity for macropodid nematodes to undergo hypobiosis has not been studied. In the case of injectable anthelmintics such as ivermectin and moxidectin, Sovell and Holmes (1996) suggested that infrequent local tissue reactions at the site of injection can restrict drug action and limit the amount of drug delivered into the blood stream, but it was not possible to assess this in our field study.…”

Enhancement of oral moxidectin bioavailability in rabbits by lipid co-administration

“…In regard to the need for an efficient antiparasitic control for onchocerciasis, moxidectin is currently under development in man (Cotreau et al 2003). In the rabbit, MLs are effective against ectoparasites (psoriatic mange; Wright and Riner 1985;Wagner and Wendlberger 2000) and nematodes (Sovell and Holmes 1996). Although there is no specific formulation available for rabbits, moxidectin represents a good alternative for broad-spectrum antiparasitic therapy in this species.…”

Assessment of a liposomal formulation of ivermectin in rabbit after a single subcutaneous administration

“…Although there is no specific formulation available for rabbits, ivermectin represents a good drug for broad-spectrum antiparasitic therapy in this species. Indeed, MLs are effective against ectoparasite, psoriatic mange (Wagner and Wendlberger 2000;Wright and Riner 1985), and nematodes (Sovell and Holmes 1996).…”