Controlling Lice in Cattle

— Written By N.C. Cooperative Extension

Cattle lice are an external parasite of cattle that continues to rob producers of pounds of gain and ultimately lower marginal returns. However, producers can effectively identify and control these parasites and improve their profitability by following a few simple steps.

During the cold winter months, lice numbers multiply. They are easily spread from one animal to another as the animals crowd together at feeding time. Eventually, the whole herd can become infested, however, usually only a few animals become extremely affected. Infested animals will often rub and scratch excessively in response to the irritation caused by lice.

Biting and sucking lice usually inhibit weight gain or even cause a gradual loss, and can result in louse-induced anemia, and lowered resistance to stresses, such as cold, wet weather. Proper planning and timely intervention can greatly reduce infestations and result in greater profits to the “bottom line”.

Both biting and sucking lice can occur in a herd. Usually, only a small number of animals will be heavily infested. There will be a few lice that survive the hot summer months on “carrier” animals, usually bulls or old cows. 

A bull’s longer, denser coat and heavier neck and shoulders prevent him from grooming efficiently. Self-grooming helps to reduce louse numbers. Nutrition, general health, and reduced effectiveness of the immune system of older cows can predispose them to louse infestations.

Confirm a suspected louse infestation by visual examination of the most symptomatic animals. Look through the hair at points along the neck, head and around the eyes, on the withers, brisket, and shoulders to look for eggs and lice. Sucking lice can occur in patches. They have narrow, pointed heads and tend to remain attached to the animal. Chewing lice are more active and have a wider, triangular head. 

There are several control options for lice but the options are fewer at this time of year. We are past the treatment date for cattle grubs, so a systemic insecticide should not be used unless a grub treatment was applied earlier. 

A whole animal spray gives the better coverage for effective louse control and is also one of the cheapest treatments. This leaves pour-ons and dusts are much less effective. 

Read the label carefully before you buy. You may find different costs for products containing the same concentration of a specific active ingredient, so generic formulations can save you money. Be sure to look at the application rate and method. Some products have an applicator or measuring device to help deliver accurate doses. This is very helpful when dose rates are just a few cc’s per head.

Beware of other cautions or restrictions on the label. It is especially important to note the time to wait between applications (two are needed for louse control because the egg or nit stage is not killed) and protective equipment to be used during application. 

Ridding your herd of cattle lice can add pounds to your cattle and improve overall efficiency, and in the process help to increase your profitability. So take steps now to control cattle lice this winter in your herd.

Damon Pollard
Extension Agent