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September 2016

Using Copper Oxide Wire Particles to Increase Dewormer Efficacy

Joan M Burke
James E Miller
Thomas H Terrill
Erin Smyth
Mohan Acharya



The greatest reduction in fecal egg count occurred in lambs treated with both COWP and albendazole. We have strong evidence that a combination of levamsole and COWP is more effective than either product used alone (in sheep).

Alternatives to synthetic anthelmintics or dewormers remain critical due to the prevalence of dewormer resistance. Some organic certifiers allow the use of copper oxide wire particles (COWP) to control barber pole worm (Haemonchus contortus). Some farmers have no effective dewormers to use. We have previously reported on the use of COWP (go to link),  which is effective against the barber pole worm, but not other gastrointestinal nematodes.


An experiment was conducted in weaned lambs to examine fecal egg counts (FEC) and FEC reduction 7 to 14 days after treatment with two sources of COWP, albendazole (Valbazen®), or a combination of albendazole and COWP. There were five treatment groups:


1.  Control (no treatment)
2.  COWP (Copasture®)

3.  COWP (Ultracruz™)
4.  COWP + albendazole

5.  Albendazole (Valbazen®)


A 2 g dose of COWP was used, but only 1 g is normally recommended for lambs. Albendazole (Valbazen®) was given at double the labeled dose at 15 mg/kg of body weight (3 ml/50 lbs.). There were between 10 and 23 lambs per treatment. The flock was determined to have resistance to benzimidazoles (same class of dewormer as albendazole) by the Drenchrite® test. The population of worms was mixed (H. contortus, Trichostrongylus spp., Cooperia spp., Oesophagostomum spp.).

There was an increase in fecal egg counts in untreated lambs  and a reduction in all other groups. The greatest reduction occurred in lambs treated with both COWP and albendazole (99.1%). The reduction with COWP alone was 12% and 58%, respectively, using Copasure® and Ultracruz™.  While numerically different, there was no statisical difference between the different forms of COWP. Albendazole alone reduced fecal egg counts by 20 percent.  Similarly, albendazole alone was not statistically different from COWP alone.



This was the first time that two forms of COWP were examined in the same experiment. Both forms of copper were found to be equally effective in this experiment. This is the first report of greater efficacy of a dewormer when combined with COWP. Because there was control of both barber pole worm and other nematode worms, which can cause problems with growth and diarrhea, this treatment approach offers hope fo rsmall ruminant farmers in the face of complete dewormer failures (resistance to all classes of dewormers).


Although it has not been published, we have strong evidence that a combination of levamisole (Prohibit®, LevaMed®) and COWP is more effective than either product used alone in sheep. Keep in mind that when using COWP in sheep, because sheep are highly susceptible to copper toxicity, you should use the lowest dose possible (0.5 to 1 g in sheep or goats less than one year of age; 1 to 2 g to adult sheep and goats). Do not use if feeds or minerals that contain added copper. It is recommended that COWP with or without an anthelmintic be used selectively, based on the criteria of the FAMACHA© system or Five Point Check©.


The original work was published in Veterinary Parasitology (2016, vol. 215:1-4). This project was funded by USDA, Agricultural Research Service, Dale Bumpers Small Farms Research Center and the USDA Organic Research and Education Initiative, Project No. 2010-51300-21641.

* Differences were not statistically significant.

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