Managing Lice on Cattle

 

Lice infestations cause significant economic losses to the cattle industry. The USDA estimates that U.S. livestock producers lose approximately $125 million annually due to cattle lice. These tiny parasites can lead to substantial economic losses as a result of reduced weight gain, decreased milk production, carcass value losses from damaged hides, and damage to fences and facilities as cattle rub against them to alleviate irritation.  Lice infestations in cattle are of particularly concern during the winter months. Understanding the types of lice that affect cattle, their life cycles, and effective management strategies is crucial for maintaining herd health and productivity.

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Biology and Life Cycle of Cattle Lice

Cattle lice are small, wingless insects that spend their entire life cycle on the host animal. The life cycle begins when the female attaches her eggs, known as nits, to individual hairs on the animal. These eggs hatch into nymphs, which resemble smaller versions of the adults. After several molts, nymphs mature into adults. The entire life cycle, from egg to adult, typically spans 3 to 4 weeks. Lice are host-specific and cannot survive more than a few days off the animal. Transmission primarily occurs through direct contact between animals, especially when they are in close proximity during feeding, handling, or sheltering. While lice populations can be present year-round, they tend to peak during the winter months, due to factors like thicker hair coats and increased animal crowding.

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Types of Cattle Lice

There are two main categories of lice that infest cattle: biting (chewing) lice and sucking lice.

1. Biting Lice: The primary species in this category is Bovicola (Damalinia) bovis. These lice feed on skin debris, hair, and skin exudates (fluid around lesion). They are typically found on the shoulders, back, and neck of the animal. Infestations can lead to skin irritation, hair loss, and the formation of scabs.
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2. Sucking Lice: Sucking lice feed on blood and tissue fluids, which can cause anemia, weight loss, and in severe cases, death.  This group includes several species:
   • Short-nosed Cattle Louse (Haematopinus eurysternus): The largest of the cattle lice, found on the neck, back, dewlap, and base of the tail.
   • Long-nosed Cattle Louse (Linognathus vituli): Identified by its bluish color and long, slender head, commonly located on the dewlap, shoulders, neck, and rump.
   • Little Blue Cattle Louse (Solenopotes capillatus): The smallest sucking louse, bluish in color, typically found on the dewlap, muzzle, around the eyes, and neck.

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Symptoms of Lice Infestation

Cattle infested with lice often exhibit specific signs, including:

• Excessive Rubbing and Scratching: Irritation from lice leads animals to rub against fences, posts, and other structures, often resulting in hair loss and damaged skin.
• Hair Loss: Patches of missing hair, especially around the neck, shoulders, and rump, are common.
• Unthrifty Appearance: Infested cattle may appear dull, lethargic, and in poor body condition.
• Presence of Lice and Nits: Close examination may reveal adult lice and eggs attached to hair shafts.

It’s important to note that other conditions, such as nutritional deficiencies or fungal infections, can mimic lice infestation symptoms. Therefore, proper diagnosis is crucial before initiating treatment.

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Management and Control Strategies

Effective management of cattle lice involves a combination of preventive measures and appropriate treatments:

1. Regular Monitoring: Especially during peak seasons (December through February), closely observe cattle for signs of lice infestation. Early detection allows for timely intervention.
2. Proper Nutrition: Maintaining adequate nutrition, including sufficient vitamin A intake, supports skin health and can reduce susceptibility to lice infestations.
3. Strategic Use of Insecticides: Various products are available, including pour-on formulations, sprays, and systemic injectables. It’s essential to understand the differences among products used to manage lice. The most common forms of insecticides include pyrethroids applied as a pour-on. Always read label instructions for dosage and withdrawal times. Rotating active ingredients is important to reduce the incidence of insect resistance. Knowing the type of lice you are dealing with will also determine the most effective ingredient and application method. For example, injectable insecticides, such as avermectins, are more effective on sucking lice. Second applications, 14 days apart may be needed as many non-systemic products do not kill the eggs.
4. Environmental Management: Maintain clean living conditions to reduce stress and minimize opportunities for lice transmission.
5. Quarantine New Additions: Isolate and treat new animals before introducing them to the existing herd to prevent the introduction of lice.

In cases where infestations persist despite treatment, it’s advisable to consult with your veterinarian or local extension agent. They can provide guidance on alternative treatments, potential resistance issues, and integrated pest management strategies tailored to specific herd conditions.

By implementing these practices, cattle producers can effectively manage lice infestations, ensuring the health and productivity of their herds throughout the year.

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References

1.  Boxler, D. J. (2017). Cattle Lice. University of Nebraska-Lincoln Extension.
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2.  Johnson, G., & Van Emon, M., (2021). Management of Lice on Livestock. Montana State University Extension.
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3.  Stokka, G., Hoppe, K., (2022). Consider causes of hair loss and itching in cattle. North Dakota State University Extension.
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4.  Whitworth, B., (2024). Winter cattle management: Controlling lice infestations. Oklahoma State University Extension.
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5. Jones, M.  (2021) Lice: A Wintertime Threat.  Oklahoma State University Extension.