Lice on cattle - Cubicle Lime (Hydrated Lime)

Some advice from AHI:

Lice and Mites at Housing

Dr Natascha Meunier, Beef Health Check Programme Manager

The housing period is usually a time when problems with lice and mites come to the surface. Winter

creates a great environment for external parasites to thrive. The animals are kept indoors, in close

contact with one another, so the lice and mites can spread easily between animals. Warm, humid

The housing period is usually a time when problems with lice and mites come to the surface. Winter

creates a great environment for external parasites to thrive. The animals are kept indoors, in close

contact with one another, so the lice and mites can spread easily between animals. Warm, humid

environments, and the long hair coats on the animals protects the lice. In the spring when the animals are back

on pasture, exposure to the sun and less close contact means that the parasites become less of a problem.

Signs of infestation

Signs of lice and mite infections can be very similar and include hair loss, itching and scratching against posts.

Severe scratching can cause wounds and secondary infections. Animals can be very itchy and irritated to the

point that it affects their behaviour and general welfare. Animals can lose weight or gain weight more slowly

than expected and may miss their growth targets. Essentially, lice and mites can cost money in performance

losses and are worth treating if there is a problem on farm.

If parasites increase in number, we can see problems in the whole group or on specific animals that may have

a lower general immunity. Large infestations in certain animals might be a sign that they have some underlying

condition that is worth investigating. Often you won’t see any clinical signs with an infestation, so be aware that

you can buy in healthy looking animals and bring parasites onto the farm for the first time in this way.

Lice come in two main groups – biting lice and sucking lice. The biting lice are also known as chewing lice and

they live on the surface of the skin and feed on outer dead layers of skin and hair follicles. Sucking lice, as their

name suggests, pierce the skin to access and feed on blood. If there are a large number of sucking lice on an

animal, the animal can actually become anaemic from blood loss, but that is only seen in severe cases. Usually,

hair loss and scratching are the most common signs for both of these types of lice. Mites burrow into the skin

and can cause extreme irritation and itching depending on the species.

Treatments available

To treat against external parasites, there are two main groups of active ingredients in the available products –

these are the synthetic pyrethroids and the clear drenches (macrocyclic lactones). In addition to lice and mites,

the synthetic pyrethroids also have action against flies and the clear drenches are also used widely for worm

control.

What if the treatment does not seem to be working?

There could be a few reasons for this: Animals might need a second treatment if there are many eggs present,

as the medicines generally do not affect the eggs. These can hatch, mature and start the cycle again within 3-4

weeks. If there is a very heavy infection, more than one treatment might also be needed.

Lice and mites usually need direct contact between animals to spread – they complete their life cycle on the

host animal. It is important to treat all animals in a group. If you only treat those animals that are showing

clinical signs the treatment will work, but they can be re-infected again as soon as the product wears off and

they come into contact with the untreated animals in the group.

Another reason that the treatment may not be working as expected is that you might be using the wrong type

of product for the parasite in question. 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. While you can see lice if you part the hair, the only way to really

know which parasite you are dealing with is for your vet to take a skin scraping around the areas of hair loss,

look under the microscope and identify which parasite is causing the problem. Your vet can then discuss which

treatment is best.

What is the best way to use pour-on product?

Before starting, make sure that you know the withdrawal period of the medicine, especially for finishing

animals. Always read the label on how to use the product correctly, as there are differences between brands.

Make sure the dose is correct for the weight of the animal in front of you; under-dosing will mean the product

is less effective.

Check if you are using a spot-on or pour-on product, remember that they can look similar but are designed to

be used differently. Spot-ons require a large concentration of the drug in one or more spots, usually between

the shoulders, from where it spreads to get adequate coverage over the animal.

Pour-ons are designed to be poured along the top of the spine and try to spread the product evenly along

the whole back. The product usually needs to reach the skin to work, so make sure the animal is clean. If the

animals are not being kept in housing, be aware that rain can wash some of the product off, making it less

effective. If the hair is particularly long, clipping along the top of the back can make this process more effective.

Always wear gloves when handling these products for your own safety, and make sure you dispose of the empty

bottles or leftover product correctly, away from water courses as many of these medicines are extremely toxic

to fish.