Haloxon: critical tests of antiparasitic activity in equids.

E T Lyons, J H Drudge, S C Tolliver

Index: Am. J. Vet. Res. 42(6) , 1043-5, (1981)

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Abstract

Critical tests were conducted in 14 naturally infected equids (13 horses and 1 pony) to evaluate the antiparasitic activity of haloxon. Single doses were administered by stomach tube to 3 horses and 1 pony (60 mg/kg of body weight), by addition to the feed of 3 horses (60 mg/kg), and intraorally by powder gun to 7 horses (65 mg/kg). Haloxon was efficacious (99% to 100%) against infections of Parascaris equorum, Oxyuris equi (mature and immature), and Strongylus vulgaris at both dosage levels. Probstmayria vivipara parasites were removed in 1 horse treated at 60 mg/kg by stomach tube and S equinus was removed (1 specimen) in 1 horse treated at 65 mg/kg with the powder gun. Removal activity against small strongyles varied from 67% to 92%, and averaged 88% in ther aggregate. Removal of S edentatus fluctuated from 2% to 100%, and was 49% in the aggregate. Haloxon was generally ineffective against Gasterophilus intestinalis and G nasalis, except that it seemed active against 2nd instar G intestinalis when administered at the 60 mg/kg dosage rate in feed and at the 65 mg/kg dosage rate by powder gun. The compound was inactive against Trichostrongylus axei, Habronema muscae, Draschia megastoma, Anoplocephala perfoliata, and A magna. Clinical signs of toxicosis were not observed after treatment. Problems were not encountered in administration of haloxon directly into the back of the mouth with the powder gun.