When cattle are housed for the winter, they are generally treated for a range of internal and external parasites.
The main parasites treated in cattle at housing are fluke and worms (internal) and lice (external).
Before treating for fluke and worms, a dung sample should be taken to determine if there is a need for an anthelmintic treatment.
Livestock that have been treated for lice at housing can show signs of lice three or four weeks after the initial treatment, leaving many farmers wondering if their initial treatment worked.
The symptoms of lice on cattle are:
- Scratching;
- Licking;
- Tail swinging;
- Hair loss;
- Inflamed skin.
According to Animal Health Ireland’s (AHI’s) Beef HealthCheck winter newsletter, animals might need a second treatment as the initial treatment generally doesn’t kill the lice eggs. These lice eggs can hatch, mature and start the cycle again.
When treating cattle for lice, it is important to treat all the livestock that are in close contact at the same time to get the best control of the parasite.
Another reason that the treatment may not be working, according to AHI, is that the wrong type of product may have been used for the parasite in question.
Tips to remember when treating for lice and mites:
- Injectable products do not usually work well against biting lice as they are on the surface of the skin and the active ingredients don’t reach them;
- Two treatments are usually needed against mites, depending on the products used.
Injectable products for treating lice will primarily treat sucking lice, and will aid in the control of biting lice, however pour-on treatments will treat both sucking and biting lice.
Before selecting a treatment to use, farmers should consult with their veterinary practitioner.
Approximately three weeks after the initial lice treatment, farmers should check to make sure their cattle are showing no signs of lice.
The reason livestock may have to be treated again after three weeks is to kill-off any lice that may have hatched from eggs since cattle were last treated.
Before using a lice treatment on forward-type beef cattle, farmers should check the withdrawal period on the product.