Efficacy of doramectin against naturally acquired adult and inhibited larval infections by some nematode parasites in cattle in New Zealand

Authors: Hooke FG, Hosking BC, Watson TG
Publication: New Zealand Veterinary Journal, Volume 43, Issue 2, pp 64-66, Apr 1995
Publisher: Taylor and Francis

Animal type: Cattle, Livestock, Production animal, Ruminant
Subject Terms: Alimentary system/gastroenterology, Animal remedies/veterinary medicines, Anthelmintics, Parasite control, Parasites - internal, Treatment/therapy, Nematode
Article class: Scientific Article

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Abstract: A study was conducted to determine the therapeutic efficacy of 1% doramectin injected subcutaneously at 200 μg/kg into cattle harbouring naturally acquired infections of inhibited Ostertagia ostertagi larvae. Sixteen yearling Friesian bulls, grazed without anthelmintic treatment throughout the autumn-winter, were selected on the basis of similar body weights and serum pepsinogen activities. After removal from pasture on day -23 they were weighed and randomly assigned to two treatment groups on the basis of this weight. On day 0, one group was given saline (1 ml/50 kg) while the second was treated with doramectin (200 ug/kg). Both treatments were given by subcutaneous injection. All stock were slaughtered 14-15 days after treatment. Moderate to high levels of adult 0. ostertagi and Trichostrongylus axei and early and late 4th larval stages of 0. ostertagi were recovered from saline-treated calves at necropsy. Doramectin was highly effective in eliminating all stages of 0. ostertagi (99.9%; p<O.OOOl) and T. axei (100%; p<O.OOOl). No evidence of lesions were detected at the injection sites at necropsy. These results confirm that doramectin is an extremely effective broad-spectrum avermectin anthelmintic with efficacy against inhibited as well as maturing larval and aduit forms of 0. ostertagi.

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