Keep sheep parasites at bay

Page last updated: Wednesday, 21 March 2018 - 11:15am

Please note: This content may be out of date and is currently under review.


The third parasite to check for is lice. A heavy infestation of sheep lice can cause severe irritation. This can lead to the affected animal becoming distressed, suffering from a loss of appetite and subsequently losing weight and condition.

Lice are a common parasite in sheep flocks, and some animals are more resilient than others to a heavy infestation.

Sheep lice spread easily from sheep to sheep through direct contact. The presence of one infested sheep indicates a potential infestation throughout the flock. Infested sheep should be treated with an appropriate product ideally after shearing.

On occasion, sheep will need to be treated when unshorn to prevent significant wool damage.

Details of current chemical treatments are available from Sheep lice control for ewes and lambs and A treatment plan for farms with lice, and the LiceBoss website.

If individual animals are found to be suffering from a heavy lice infestation, and rubbing to the point of causing wounds, they should be treated ahead of any planned routine flock treatment.

To help prevent lice infestations, quarantine any sheep that you acquire from outside your property until you can be sure they are lice free. Build and maintain sheep-proof fences to keep out infested strays.


Many seasoned sheep owners describe running a flock of sheep as a wonderfully rewarding activity. Unfortunately, at some point you will almost certainly observe a parasite and pest infestation in your sheep.

You need to monitor your animals at least every two days and be able to recognise if your sheep are suffering from an infestation.

Some owners regularly weigh their sheep (for example, every four weeks) to assess their condition and growth. This is a time-consuming, but valuable management method. Regular weighing is also a good time to check your sheep for parasites.

Your vet is a good source of information and you may find that local farmer groups or breed groups can also offer support.

The department also has an array of sheep care references.

Animal welfare and the law

The law governing offences of cruelty to animals is the Animal Welfare Act 2002 (the Act).

‘Cruelty’ does not only mean beating or starving an animal. If an animal "suffers harm, which could be alleviated by the taking of reasonable steps", the person in charge of that animal could be prosecuted.

By failing to treat your animal, you could be guilty under the law if ‘reasonable steps’ in terms of prevention and treatment are not undertaken.

In WA, the Act is administered by the Department of Primary Industries and Regional Development.

Animal welfare tips

Sheep need to be monitored at least once every two days by someone who can spot the signs of a pest infestation.

All new animals to the property need to be held in a quarantine area before being introduced to other stock.

Quarantine yards are a good place to hold sick or infested animals especially if they need regular treatment. It will also help with preventing parasites from spreading to other animals.