Single vs. double dose of copper oxide wire particles (COWP) for treatment of anthelmintic resistant Haemonchus contortus in weanling lambs

Data from 43 lambs within 3 treatment groups in a double blind study were included in the experiment. Treatments were administered as a total of 2 boluses, each given on separate occasions (day 0 and day 42), so that each lamb received either 2 placebos, a single dose of 2 g COWP followed by placebo, or two doses of 1 g COWP. Strongyle-type fecal egg counts (FEC) were performed at initial treatment (day 0), on day 10, at second treatment (day 42), on day 52, and at study end (day 84). At the start of the trial, mean ± standard deviation FEC were 1634.4 ± 825.2, 2241.7 ± 1496.8, and 2013.3 ± 1194.2 epg for the 2 g, 1 g × 2, and control groups, respectively. At the end of the trial, FEC were 757.1 ± 825.3, 483.4 ± 557.2, and 1660.0 ± 1345.3 epg for the 2 g, 1 g × 2, and control groups, respectively. Lambs given a 2 g single dose of COWP or a 1 g dose of COWP twice had reductions in strongyle-type FEC (p ≤ 0.01) from trial start to trial end, whereas lambs given placebo did not. Average daily gains did not differ significantly among groups. Although copper is potentially toxic to sheep, no signs of toxicity were observed during this trial, which was consistent with similar studies at this treatment dose. The study indicated that administering COWP to lambs at weaning reduced FEC.