Q.
Can copper be used as a dewormer?
A.
Yes and no.
Copper oxide wire particles
In recent years, copper oxide wire particles (COWP) have been evaluated as a potential dewormer. Research has demonstrated the efficacy of copper oxide wire particles against barber pole worms (Haemonchus contortus), especially in lambs/kids. Copper oxide wire particles are tiny metal rods of copper oxide. They are put in boluses or capsules for treatment of copper deficiency. Unlike copper sulfate, the copper in copper oxide is slow release and poorly absorbed. When used according to recommendations, copper oxide wire particles pose little risk of copper toxicity.
It is recommended that the cattle boluses (12.5 and 25 g) of copper oxide be repackaged into smaller dosages for deworming sheep/goats. Gel caps can be purchased from pharmacies or Amazon. The 2 g goat bolus can be used to deworm adults sheep/goats, but the 4 g bolus is more copper than is recommended for deworming. In fact, it is recommended that you always use the smallest effective dose of copper oxide wire particles for deworming, usually 0.5 to 1 g for lambs/kids and 1-2 g for mature sheep/goats. It is also recommended that COWP be given using the principles of "targeted selective treatment," only treating those animals that require deworming and/or would benefit from treatment. There is some evidence that giving copper oxide wire particle in combination with a dewormer may increase the treatment efficacy of either product alone.
Copper sulfate
Copper sulfate is an old-time dewormer that killed sheep, so people stopped using it due to the risk of copper toxicity. Plus, safer more effective dewormers came onto the market. We also stopped using copper sulfate in foot baths for fear the sheep would drink the foot bath solution. Copper has always been a red flag for sheep producers, as sheep are by far the species most susceptible to copper toxicity. Goats need and can tolerate more copper.
High copper minerals
It's generally not recommended that copper be added to minerals or that a high copper mineral be fed, especially to sheep. You cannot control the consumption of free choice minerals. Some animals may eat too much, some not enough. At the same time, it's important to correct any copper deficiencies. Copper-deficient animals are more susceptible to parasites. Signs of copper deficiency include swayback, steely wool, loss of crimp (in wool), loss of pigmentation, and "fish tail" (in goats).
Anemia (blood loss) can be a sign of copper deficiency, but it is hard to know whether the anemia is the result of a copper deficiency or internal parasites (barber pole worms). Marginal deficiencies of copper aren't always apparent. To truly know if you have a copper deficiency situation, you should test some animals. Unfortunately, blood won't tell us enough. You need to test some livers. Obviously, this needs to be done post-mortem. If your animals are copper-deficient, you can supplement them via boluses or mineral/feed. Cattle minerals are a way to get more copper in sheep.
Copper metabolism
Copper metabolism is complicated. The aborption of the copper is more important than the content of copper in the ration. There are various mineral interactions that impact the absorption of copper. For example, molybednum forms an insoluble complex with copper that prevents copper from being absorbed. Too much molybendum can cause a copper deficiency, whereas low levels of molybednum can cause copper toxicity. Iron and sulfur are also antagonists of copper. Due to the nutritional complexity, copper supplementation should not be taken lighly. "Blanket" statements or recommendations (regarding copper) are ill-advised. Every farm/ranch is different. While sheep are more prone to copper toxicity (especially some breeds), copper toxicity is also a risk in goats.
Despite the greater risk to the animals (especially sheep), copper sulfate and copper oxide wire particles may be approved by organic certifiers (for deworming). Producers who use copper sulfate should do so with extreme caution, being careful not to overdose, even slightly overdose. In other words, it's very important to weigh every animal before dosing and to carefully measure out the dose. Copper oxide wire particles are preferable, due to the lower risk of copper toxicity. Feeding a high copper mineral (not recommended) should be done with extreme caution, especially with sheep. It's generally recommended that sheep not be fed any feeds or minerals with added copper, unless a copper deficiency has been diagnosed (via laboratory testing).
5/28/21
Additional reading
Copper oxide wire particles: Best Management Practices (WormX)
Copper oxide wire particles: Keeping it Safe: Timely Topics (WormX)
Copper poisoning in sheep - NADIS UK