Red Deer Cervus elaphus Nematodes

Andrews and Lancaster (1988) and Andrews et al. (1993) reported, on the basis of field observations, that a single dose of injectable ivermectin at 200 | g kg-1 as recommended for cattle, sheep and horses appeared to be insufficient to control nematode infections in red deer, as is the case of goats treated at the sheep dose (reviewed by Conder and Campbell, 1995). Based on egg/larval count (Andrews et al., 1993) or egg/larval/worm count (Mackintosh et al., 1993) data, 400 |g kg-1 of ivermectin did appear to be slightly more efficient than 200 |g kg-1 when administered subcutaneously against D. viviparus and gastrointestinal worms; the former dose is widely used now in red deer (Connan, 1996). Consistent with the above data for injectable ivermectin, Connan (1991) reported that a group of red deer, treated orally with ivermectin at 200 |g kg-1 at housing (December) and again 4 weeks later, exhibited poor condition and appreciable worm burdens (predominantly ostertagids) at necropsy (April). The stage of development of the worms at necropsy, the presence of umbilicated nodules consistent with those of ostertagiasis and the lack of exposure to infection during housing suggested an inhibited population that had not been controlled adequately by ivermectin treatment. Further, Connan (1997) found that 400 |g kg-1 of ivermectin administered subcutaneously was 100% effective against adults and developing larvae and 95% effective against hypobiotic larvae of ostertagids, based on worm counts. D. viviparus may not require the higher dose, since a subcutaneous dose (Mackintosh and Mason, 1985; Mackintosh et al., 1985) or an oral dose (Mackintosh et al., 1990) of ivermectin at 200 |g kg-1 was found to be 100% effective against this nematode, based on worm counts or faecal larval counts, respectively. Kutzer (1990), using two oral doses of ivermectin administered at 200 |g kg-1 and given at a 4-week interval, found the treatment regime to be 100% effective against gastrointestinal nematodes, D. viviparus, and Varestrongylus sagittatus, but not effective against Elaphostrongylus cervi, based on egg and larval counts. Two 300 |g kg-1 doses of ivermectin given on consecutive days in a granulated food (2.5 kg ivermectin pre-mix (0.6% ivermectin) in 500 kg of granulate) provided 89.3,91.2,90.3,95.3 and 99.6% reductions in Trichostrongylidae, Trichuris spp., E. cervi, V. sagittatus and Dictyocaulus noerneri, respectively, 18 days post-treatment compared with pre-treatment levels, as determined by flotation and Baermann methods (Malczewski et al., 1998). Kutzer (2000) also reported that use of an ivermectin pre-mix (0.6%) administered at 400 |g kg-1 twice at an interval of 1 week was effective in controlling intestinal and lung nematodes in red deer. To assess persistence, red deer artificially infected with D. viviparus were treated topically with ivermectin pour-on at 500 |g kg-1 (Rehbein and Visser, 1997). Ivermectin was more than 99% effective against infection with D. viviparus for a mininum of 28 days following treatment. Mackintosh et al. (1990) and Mason et al. (1990) observed similar results based on faecal larval counts, taking an approximately 21-day pre-patent period for the parasite into consideration.

Moxidectin in a pour-on formulation administered at 500 |g kg-1 was evaluated in red and wapiti x red hybrid deer against natural infections of lungworms (D. viviparus) and abomasal nematodes (Ostertagia type)

(Waldrup et al., 1998). In red deer, moxidectin was 100% effective against all stages of the lungworm and, in wapiti x red hybrids, the treatment was 100 and 99.7% effective against adult and immature stages, respectively. Against the Ostertagia-type nematodes (genera assumed to be Ostertagia, Spiculopteragia, Skrjabinagia and Apteragia) in both red and wapiti x red hybrid deer, moxidectin was >99.9% effective against all stages. Similar results in red deer had been reported previously by Mackintosh et al. (1993) and Middelberg (1994); they also found moxidectin to be effective against Haemonchus, Trichostrongylus and Oesophagostomum spp. Mackintosh et al. (1997) found that based on worm counts, moxidectin in the pour-on formulation administered at 500 |g kg-1 provided protection for up to 42 days following treatment against artificial challenge with a mixed nematode population, including D. viviparus, Spiculopteragia asymmetrica, S. spiculoptera, Ostertagia leptospicularis, Skrjabinagia kolchida, Trichostrongy-lus axei, Cooperia spp., Oesophagostomum spp. and Chabertia spp.

Eprinomectin pour-on applied at 500 |g kg-1 was reported to be safe and effective against adult and fourth-stage larvae of D. viviparus, Ostertagia spp., Trichostrongylus spp. and adult Oesophagostomum spp. in red deer (Gogolewski et al., 1997a,b).

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