18 October 2023

Controlling lice at housing

Alan Dillon, DairyBeef 500 Campaign Co-Ordinator, tells us about lice treatment and what can happen if we fail to treat.

Lice treatment is usually carried out at housing but repeat treatment is necessary in many cases. Lice infestations left untreated have the potential to significantly reduce weight gain in finishing cattle, in what is an expensive time in a finishing animal’s life.

There are basically two types of products used in the control of lice. You have the pour-on synthetic pyrethroids and injectable or pour-on ivermectins. Injectable and pour-on products can be used to manage mites and sucking lice, but only pour-on products are effective against biting lice. The pour-on products will disperse throughout the fat layer, which is how they become effective against biting lice, as they do not ingest blood.

For pour-on products, correct administration is key to effective control. If using a pour on to control lice, it is generally best to clip the backs of cattle. It is also important not to under dose. Lice spread very readily between cattle and the main route of transmission is by direct contact, so all contact animals should be treated at the same time. It is also important to treat any bought-in animals before they are let join any groups of housed cattle that have been already treated.

Cattle should be checked two to three weeks after the initial treatment just to make sure they are not showing signs of infestation. The reason you may have to treat again after two to three weeks is to kill off any lice that have hatched from eggs since your last treatment.

The video below, by Animal Health Ireland, has a useful link on how to manage lice at housing. Further information available here.