Finn's Corner

May 2015

As the temperature is cooling, it is time that we start to keep an eye out for lice in our herds. Lice populations significantly increase in winter, which is fast approaching. They prefer cooler skin temperatures and the denser winter coats. Generally lice are species specific and do not survive or breed on other animals or humans. For instance cattle lice will not affect sheep and vice versa. Hence we will discuss the effects of lice on cattle, horses and sheep including survival preferences, symptoms, and management.



Sheep are affected by different types of lice including body lice, face lice and foot lice. The body louse however  is the one most commonly seen. It appears to be more responsible for causing a serious problem compared to other types of sheep lice. Unlike lice on other species, lice affecting sheep survive at temperatures of 37°C and prefer a high humidity. Body lice do not like extreme changes in these conditions and in order to maintain survival will  move up and down the wool fibres. Hence, they cannot survive for long on fence posts or yards off of the sheep.

Lice on sheep are unique in the sense that they do not suck blood but rather feed on dead skin, as well as skin secretions and bacteria. This can result in a thickening of the skin.


Their life cycle is represented by the diagram below:

sheep lice

Image accessed at


Sheep that are recently infested with lice are more sensitive than those that have had them for long periods. Hence they will show more symptoms. Symptoms of lice infestation can take time to show depending on the size of the lice population along with sheep sensitivity. There are a variety of chemical treatment options available including pour-ons, dips and sprays which effectively treat lice on sheep.


More information can be found via the following link



There are 2 types of lice on horses, ones that bite and ones that suck. Biting lice on horses are usually observed around the back of the head and body whereas sucking lice are mostly found at the base of the mane, at the top of the tails and even around the fetlocks. Horses with longer winter coats are more at risk of lice infestations. An example of sucking lice is shown below:



In severe cases lice can cause weight loss and anaemia.

Treatments are often sprays, washes, powder insecticides or pour ons. If a horse is rugged or is consistently in work all rugs and gear should also be sprayed and left unused for 14 days. Even objects coming into contact with the horses such as brushes or blankets can spread the lice to other horses if not treated. Lice can live for a few hours off of the horse on fences or in stables where the horse has rubbed.


More information can be found at the following link



There are 6 species of cattle lice in Australia. These are very similar to those found on sheep and horses.

An image of cattle lice and eggs is displayed below:



Cattle lice have a life cycle of 3-6 weeks. The eggs can be seen glued to the hairs. In general insecticides registered for use on cattle do not provide adequate control against louse eggs, meaning that even after treatment is applied the eggs can still hatch and restart the cycle. When and how often to treat cattle depends on individual circumstances. There are 4 types of treatment available including sprays, pour-ons, insecticidal ear tags and certain worm drenches.


More information can be found at


General Symptoms of lice include:

  • damage to fences, yards and trees
  • hair loss
  • rubbing, biting and scratching
  • poor, rough coat
  • skin wounds and raw areas

Lice infestations are more likely to impact animals which are:

  • diseased
  • nutritionally stressed
  • aged
  • in poor condition


For more information on treatment product feel free to contact us at the clinic. Just remember no matter what product you use you must follow the manufacturers instructions and withholding periods.

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