When it comes to external parasites, horn flies get the most attention, but it is important not to forget about lice. Most lice species suck blood, and uncontrolled lice populations can reduce red blood cell counts in cattle by 75%. This blood loss results in reduced daily gain in growing cattle and reduced body condition scores in cows and bulls. Controlling lice populations is important from both a performance and animal welfare standpoint. Proper lice management will help cattle get through the winter in better shape.
The cattle tail louse (Haematopinus quadripertusus) is a subtropical lice species that prefers warmer weather and sucks blood. This species has limited geographic distribution in the U.S. but is found in some subtropical areas along the Gulf Coast. It is important to be aware that treatment timing for the cattle tail louse will differ from the four species discussed below.
The short-nosed (Haematopinus eurysternus), long-nosed (Linognathus vituli) and little blue (Solenopotes capillatus) lice are also blood suckers. The chewing lice (Bovicola bovis) doesn’t feed on blood but can be a welfare concern.
The rest of this article will focus on the four species of lice (short-nosed, long-nosed, little blue and chewing) that prefer cooler weather. During warmer weather, these species undergo estivation and may be found hiding between the legs and skin folds of cattle, out of the sun. As temperatures cool, these lice become more active and are found primarily along the neck, shoulders and back of cattle. Winter hair coats provide increased protection and a more favorable reproductive environment for lice.
Lice are easily transmitted by physical contact between cattle. It is critical that all animals in the herd be treated to prevent untreated animals from spreading lice to those already treated. Don’t forget to treat any purchased animals or animals moved from another location before adding them to a group that has been treated.
Treatments are best applied after temperatures have consistently been below 80ºF. Treating too early can result in reduced control.
Several options are available for treating lice. Some products require two applications for control while others only require one. Always follow label directions to enhance product performance. Application of pour-on dewormers and insecticide products should generally be applied down the midline of the animal from the neck to the tailhead to maximize control. Avoid placing all the product in one spot.
