Monday, May 19, 2008

Is it safe to deworm with copper?

Recent press announcements, including this blog and the last Wild & Woolly newsletter, have touted the use of copper oxide wire particles (COWP) as a deworming agent in sheep and goats. Similarly, at the 2008 annual meeting of the Southern Section of the American Society of Animal Science, a graduate student presented the results of a study in which mature ewes were dewormed with copper sulfate.

grazing lambCopper sulfate is an old-time anthemintic whose use was discontinued due to copper toxicity issues. In fact, the mention of copper (in any form) as a deworming agent should automatically send up a red flag to most sheep producers who understand sheep's sensitivity to copper. [Goats require and can tolerate much higher levels of copper than sheep.]

At the same time, producers, especially goat producers, shouldn't disregard the potential of copper oxide wire particles as a deworming agent. COWP may offer an alternative to producers who are experiencing complete anthelmintic failure or who seek non-pharmaceutical approaches to worm control.

As compared to copper sulfate, copper oxide wire particles are poorly absorbed, thereby reducing the risk of copper toxicity. Researchers have experimented with different doses of COWP and frequencies of treatment to determine not only effectiveness of treatment(s), but also the effect of treatment on copper concentrations in the liver and the risk of copper toxicity.

In the research trials, COWP have been used in sheep and goats, without creating unsafe levels of copper in the liver and without risk of copper toxicity. Most of the research has been done with hair sheep and meat goats. Results have varied. COWP appear to be more effective in young animals than mature ones. Research is on-going. A summary of research trials can be found at

COWP should not be the only method of parasite control on a sheep or goat farm and should not be used sub-therapeutically. COWP only work on the barber pole worm.

Read article Copper toxicity revisited: should I deworm my sheep (or goats) with copper oxide wire particles (COWP)? This article discusses the risk factors for copper toxicity.