Written by: Barry Whitworth, DVM Senior Extension Specialist/BQA State Coordinator Department of Animal & Food Sciences Ferguson College of Agriculture
Cattle lice costs Oklahoma cattlemen millions of dollars each year in decreased weight gains and reduced milk production. If cattle producers have not treated their cattle for lice this fall, they need to consider what type of lice control to initiate. This is especially true for cattle producers that had problems in the previous year. Cattle producers should monitor cattle closely during the months of December, January, and February. Producers should not wait until clinical signs appear before beginning treatment.
The life cycle of the different species of cattle lice are very similar. The life cycle begins with the female louse attaching her egg to a shaft of hair. The egg will hatch as a small replica of the adult. After several molts, the adult will emerge. The cycle takes around 3 to 4 weeks to complete. These newly hatched lice will spend their entire life on the host and are host specific which means cattle cannot be infected with lice from other animals.
Small numbers of lice may be found on cattle in the summer, but high populations of lice are associated with cold weather. Since cattle tend to be in closer proximity to each other in the winter, lice can spread easily between cattle. A small percentage of cattle tend to harbor larger numbers of lice. These animals are sometimes referred to as “carrier animals”, and they may be a source for maintaining lice in the herd. As with many other diseases, stress also contributes to susceptibility and infestation.
Signs of lice infections in cattle are hair loss, unthrifty cattle, and hair on fences or other objects. If producers find these signs, they may want to check a few animals for lice. They can check for lice by parting the hair and observing the number of lice per square inch. If an animal has 1 to 5 lice per square inch, they are considered to have a low infestation. Cattle with 6 to 10 lice would be considered moderately infested. Any cattle with more than 10 lice per square inch are heavily infested.
Cattle have two types of lice. One type is the biting or chewing louse. These lice have mouth parts that are adapted to bite and chew the skin. The second type is sucking louse. These lice have mouth parts that will penetrate the skin and suck blood and other tissue fluids. It is not uncommon for cattle to be infested with more than one species of lice.
The biting or chewing louse is Bovicola (Domalinia) bovis. This type of lice feeds on hair, skin, skin exudate, and debris. Typical clinical signs with this type of louse are hair loss, skin irritation and scabs on the skin. They are found on the shoulders and back.
Four types of sucking lice can be found in the United States. The first is the “short nose” louse or Haematopinus eurysternus. This is the largest cattle louse. This louse is found on the neck, back, dewlap, and base of the tail.
The second is the “long-nose” louse or Linognathus vituli. This louse is bluish in color with a long slender head. This louse is found on the dewlap, shoulders, sides of the neck, and rump.
The third is the “little blue” louse or Solenoptes cappilatus. This louse is blue in color and is the smallest cattle louse. This louse is found on the dewlap, muzzle, eyes, and neck.
The last is the “tail” louse or Haematopinus quadripertuses. This louse has been found in California, Florida, and other Gulf Coast States. This louse is found around the tail.
The sucking lice have the potential to cause severe anemia if the numbers are high. This can result in poor doing cattle or in extreme cases death. They also can spread infectious diseases. The long-nose louse has been found to be a mechanical vector for anaplasmosis.
| Image | Lice |
|---|---|
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Bovicola (Domalinia) bovis |
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Haematopinus eurysternus |
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Linognathus vituli |
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Solenoptes cappilatus |
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Haematopinus quadripertuses |
Prevention of lice infestation should begin in the fall. Producers should not wait for clinical signs to appear before beginning treatment. Several products are available to control lice. Producers should read and follow the label directions. Producers should keep in mind that many of the lice control products require two administrations to control lice. Failure to do this may result in cattle having problems with lice infestations.
Some producers have complained that some products do not work. These complaints have not been verified; however, this is a good reason to consult a veterinarian for advice on what products to use. Most treatment failures are associated with incorrect application not resistance. Proper application of Pour-On insecticides is to administer from the withers to the tailhead. Also, the proper dose is essential for good control.
Cattle producers need to consider a few other things in lice control. Since cattle in poor body condition are more prone to lice infestation, producers need to be sure that the nutritional needs of their cattle are being met. Cattle that have a history of lice infestations should be culled. Lastly, any purchased cattle need to be inspected for lice before entering the herd. If lice are found, the animals should be isolated and treated before entering the herd.
If producers would like more information on lice in cattle, they should contact their local veterinarian or Oklahoma State University County Extension Agriculture Educator. They may also want to read Oklahoma Cooperative Extension Fact Sheet Beef Ectoparasites VTMD-7000.
