As winter approaches, it is important to check your cattle for lice, especially if they are showing signs of itching or rubbing. Lice numbers can start building in autumn then peak during winter, particularly in poor or dry seasons when cattle are under nutritional stress. A strategic treatment early in the season can provide effective control.
Lice infestation causes irritation to the skin, which may contribute to low weight gains or loss of condition of cattle that are stressed or running on low levels of nutrition, especially during cold winter weather. In addition, the effects of itching, licking and rubbing irritated skin are likely to have an economic impact. For example, a scruffy coat may reduce sale price and damage to the hide can reduce its value. Another indirect cost of lice is associated with damage to fences, posts and trees due to cattle using them as rubbing stations.
Cattle lice are small, wingless insects about 2 - 5 mm in length. There are two different types of lice found on cattle in Australia - biting lice, which feed on skin debris, and sucking lice, which feed by sucking blood and tissue fluids from the skin. Both types cause skin irritation and heavy infestations of sucking lice can also lead to anaemia.
Lice occur commonly on dairy and beef cattle in all states of Australia. Lice are spread by direct contact between cattle, therefore, problems are more likely to be seen where animals are held in close proximity.
Lice populations show seasonal changes throughout the year. The numbers of lice build up during late autumn and winter, peak in late winter and early spring and then decline to low levels in summer. Severe infestations can, however, occur at any time of the year, particularly during drought when animals are in poor condition. Excessive lice infestations could indicate underlying stress, requiring further investigation.
While itchy, inflamed skin is highly suggestive of lice infestation, the presence of lice can only be determined by close inspection of the skin surface and hair. Cattle need to be restrained in a cattle race or crush for close inspection. The lice are found close to the skin surface and the eggs are attached to the hairs. If you are unsure if lice are causing the problem, consult with your local veterinarian.
If cattle are itching due to lice, treatment is recommended. Since infestations are often linked to stress, the underlying cause of the stress should also be identified and addressed where possible.
In most cases, treatment in late autumn or early winter will provide good control of cattle lice. Treatment at this time will knock out any lice that may be present at the start of the lice season and reduce the level of challenge during winter. It is critical that all cattle on the property are effectively treated at the same time.
IVOMEC® Pour-On for Cattle* is an ideal choice for the autumn/winter treatment due to its persistent activity against biting and sucking lice infestations for up to 56 days with the added convenience of a pour-on.
Once treatment has been conducted it is important to develop an integrated parasite management program, including implementation of a lice biosecurity1 or eradication plan2 to prevent new infestations.
With early diagnosis and strategically timed treatments, the impact of lice on your herd can be minimised. Speak to your local animal health advisor to determine the most appropriate management plan for your area.