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Controlling lice in cattle and goats

One of my most vivid memories from when we started farming was my first meeting with a cow louse. I had been checking cows for impending births, which involved giving all their tail heads a scratch so I could check the condition of their ligaments.

It was a sunny February day so when my head was itchy upon returning to the house I just assumed it was from my toque making my head hot. But it wouldn’t stop.

I checked in the mirror just as one of these horrid things crawled onto my forehead. Much girlie screaming ensued.

Once I calmed myself I called my neighbours. When they quit laughing they told me my cows had lice — not a big deal, happens all the time, and they wouldn’t live on me. The larger concern with lice is their economic impact on the herd.

Damage from lice

There are two types of lice: sucking and chewing. The sucking lice pierce the host’s skin and draw blood. They’re controlled with injectable wormers such as ivermectin.

Chewing (biting) lice have chewing mouthparts and feed on particles of hair, scab and skin exudations. These and can only be controlled by external lice-control products. The wounds and skin irritation produced by these parasites result in discomfort and irritation to the animal. Parasites can transmit diseases from sick to healthy animals.

Irritation from louse feeding causes animals to rub and scratch, causing raw areas on the skin or loss of hair. Weight loss may occur as a result of nervousness and improper nutrition. Milk production is reduced about 25 per cent. Also, the host is often listless, coats are rough, and in severe cases the loss of blood to sucking lice can lead to anemia.

In general, infested livestock cannot be efficiently managed to realize optimum production levels. Lice diminish the gains attained by their feed and if very bad can cause death. University of Nebraska–Lincoln studies and other studies indicate that moderate to heavy lice populations may reduce weight gains of calves by as much as 0.21 pounds per day.

Controlling lice

When we first found lice in our cattle we only had three cows. We bought lice-killing powder and followed the instructions but the lice just came back.

I was told to wipe them down with white vinegar. That helped, but within a month they were back to rubbing all their fur off on the barbed wire. We tried pour-on medications from the vet, but the lice just kept coming back even when we repeated the treatments in two weeks to kill the new hatch before they had a chance to lay eggs.

Then I read that lice infestation can be linked to low vitamin A. Interesting, since vitamin A is stored in the liver for three months from the summer grass and this yearly lice ritual started in February, about three months from when the cows were given their vitamin A&D fall shots and right at calving which would be a heavy nutritional draw on the cows. We needled all the cows with A&D, applied lice powder and waited. The lice didn’t come back.

The source

The burning question in my mind was, “Where did they come from?” We hadn’t brought in new stock or worn any farm clothes to handle other herds.

Research tells us that once lice are in the herd they are easily spread from animal to animal through contact, but many lice are actually introduced to a new herd by hitching a ride on flies. Since we live right next door to the community pasture this was plausible.

Louse populations vary seasonally, depending largely on the condition of the host. Most sucking and biting lice begin to increase in number during the fall and reach peak populations in late winter or early spring.

Goats

We thought we had this all figured out. Then we got goats. The same cycle started about three years after they came home. Once winter came they were covered in the little bugs but — unlike with the cows — we couldn’t get them under control.

One of the problems we had with the goats was that they were housed mainly indoors, so the sun wasn’t helping our fight. We used many products on them but none of them were actually licensed for goats and the problem was not resolving. Then we discovered a louse powder that actually listed goats on the label and we got control. It is called Dusting Powder and it is made by Dominion Veterinary Laboratories Ltd. in Winnipeg, Man., and is available in Manitoba at veterinarians and livestock supply stores. Pour-on chemicals do work also but the meat and milk withdrawals are often too long for use on meat kids.

The one product that we were told to try topically was diatomaceous earth, which is not recommended. The little shells it is made of are not to be breathed in because they can cause lung damage, much like asbestos, and opened up a whole new batch of issues for us. This is dangerous for the humans involved in the application — not just the animals that are living in the dust it generates. Wiping them down with white vinegar was a better alternative. †

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