Farmers could risk production losses and welfare issues in their cattle this winter if they fail to protect them from lice.

Responsible Animal Medicines Advisor (RAMA) Mark Pass says farmers shouldn’t be reactive when it comes to treating stock for lice and should protect them at housing.

“Lice are often found in low levels in many herds, but when housed, infestations can rapidly increase. Certain farmers will only treat when they see signs, by which time, some production losses will have occurred as well as being a welfare issue,” he says.

NADIS estimates cattle heavily infested by lice can see production losses up to 10% due to reduced feeding time and damaged hides. Scratching may also produce wounds or bruises and can lead to secondary skin infections and skin trauma.

Type of lice and production losses

It is important to know the type of lice affecting cattle. The two main types are: chewing lice and sucking lice.

Chewing lice cause considerable irritation to affected cattle, which they react to by rubbing or scratching, resulting in patches of hair being pulled or rubbed off, most often over the neck and shoulders.

Sucking lice can cause anaemia in severe infestations, particularly in young calves and have been implicated in the spread of tick-borne fever and ringworm.

How to detect

Signs to look out for include:

• Baldness

• Skin damage particularly across the head and back

• Frequent scratching.

Lice are visible to the naked eye and, if present in large numbers, can be seen by parting the hair, particularly along the back.

Eggs are whitish and glued to hair shafts, adult chewing lice are reddish-brown, about 2mm long with a brown head. Sucking lice have smaller, narrow heads, designed for piercing the skin. Hair samples can be analysed by a vet to identify the correct species.

Treatment considerations

When it comes to treating lice, it is vitally important all animals being housed together are treated at the same time, says Mr Pass.

It is recommended to treat all the stock at the same time as if you miss treating just one animal infested with lice, they can go on and reinfect the herd after treatment. It is also important to remember to treat any bought-in cattle, he says.

“When it comes to choosing the correct product for treating lice this is something that should be discussed with your animal health provider. It is important to know if any problems are being caused by chewing or sucking lice as some products such as injectable MLs work less well against chewing lice.”

He adds: “Lice are easy to manage when the treatment is applied correctly. When farmers wish to protect their stock from lice as well as worms and fluke, they can use a combination product containing moxidectin and triclabendazole like CYDECTIN® TriclaMox® Pour-On.

This comes with a lice free guarantee* from housing to turnout and has a rainfast formulation which means that rainfall before or after treatment will not affect the efficacy of the product.

What else can you do to prevent an infestation?

Zoetis vet Ally Anderson says alongside treatment there are other management changes farmers can adopt to prevent a lice infestation in their cattle this winter.

“If you are buying in cattle or adding any new animals to the group it is important to make sure they have been treated and are free of lice before incorporating them into the herd.

“Clipping coats, which is often done down the back to prevent overheating, can also reduce the lice burden as they thrive in thick coats,” she says.

Ms Anderson adds: “Something so small as a louse can be devasting in terms of production losses and the welfare implications in a herd, so it is important to make sure you are on top of it.