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  • Writer's pictureDr Emily Boreham MRCVS

Drug-Free. Effective. Could a COWP copper-bolus be your dream wormer?

Short answer: yes! But only if you're worming a non-pregnant goat or cow to prevent Barber's Pole Haemonchus worms. For everything else, its back to the drawing board.

So what is it?

Well its not just a copper supplement. It is a capsule loaded with small copper wires: Copper Oxide Wire Particles, hence the name COWP. The waste product of the electrical industry. The structure of the wires seems as important as the copper itself - one without the other is ineffective.

The gelatin capsule degrades rapidly and releases the wires into the first compartment of the 4-stomach system - the abomasum. They slowly breakdown over about 12 weeks.

What does it do?

The copper is toxic to worms, but the jagged edges of the wire has a physical effect too. One study also found the wires worked symbiotically with a worm-trapping fungus called 'Duddingtonia flagrans'. As the wires only stay in the abomasum, they'll only kill Haemonchus contortus - the Barber's Pole worm. But that's not a bad thing, we don't really worry as much about the tapeworms and the lower intestinal nematodes. COWP is not going to help at all against flukes, coccidia or lungworm.

How effective is it?

I like placebo controlled, double blind trials the best - so when we look at those we find an average of 89.0% reduction in FEC of Haemonchus in adult goats, given a 4g bolus, for 6 weeks. This then tails off until no effect is noticed by week 12.

The trial results to the right is a 2g bolus given to 8 month old lambs. You'll see a strong initial effect that then tails off between week 4 and 12.

This level of efficacy is on-par with best results for the worming drugs, and of course doesn't have the resistance problem.

What about side effects - is it safe?

The copper gets slowly absorbed. This a good thing for goats and cattle - they thrive on good levels of copper. You'll see stronger hooves, shinier coats, better weight gain, higher milk yield and better herd fertility. I couldn't find any studies who could distinguish what is due to worm reduction and what is purely due to copper - its probably both.

BUT: too much copper is a bad thing. Excess copper is stored in the liver, this can reach damaging levels in any animal but sheep are exceptionally sensitive to this. The maximum safe dose for sheep or kids is 2g.

One study monitored lambs born to ewes given a 4g bolus during pregnancy. The lambs had higher liver enzymes at birth, lower birth weights and failed to catch up with the weight gains of the non-treated control group. The conclusion is the developing liver is mildly damaged by the high copper levels in the mother's blood stream. So perhaps COWP is not for our pregnant ewes & nannies.

How easy is it to use?

I'll have to get back to you on this one! It doesn't look like much fun, and the people that claim its easy haven't met Rita my stubborn Golden Guernsey.

I've found three methods recommended. A cat-pill popper, a proper bolus gadget and bananas. I'm going to start with bananas!

Where do I get it from?

The use of COWP has been established in the USA for many years, its normal practice for goat keepers. But it hasn't taken off here yet, so you'll need to import a supply. I ordered a pack of 25 x 4g Ultracruz boluses for my goats through a website called Storkz. Included the importation tax & delivery it was £35. You can get Ultracruz and Copasure on ebay too, listed in dollars so real-time cost will depend on the exchange rate but its about the same.

I will keep you updated on how I get on. I've just done a FEC and its all clear, so I won't be able to report on efficacy. I'm just using them as prevention. Its early days but I'm worried its going to be a bad Haemonchus season this autumn, some of my clients have reported sudden deaths - a trauma I would be devastated by, so I'm on the prevention-mission.

Good luck with your own herds,


All blog-readers get a 50% discount on faecal worm testing at, just put BLOG in the offer code box.

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