Department of Agriculture, Western Australia Sheep arthritis

Farmnote 4/1994
By Fiona Sunderman, District Veterinary Officer, Narrogin and Don Moir, District Veterinary Officer, Albany

Summary

Discusses causes, clinical signs, treatment and prevention of arthritis in sheep, an inflammation of the joints of the legs. Chronic arthritis leads to severe loss in production and sometimes death of the animal.

Arthritis in sheep is most commonly an inflammation of the joints of the legs. It results from damage to structures within these joints. The disease cause greatest economic loss in its chronic form, which results in severe loss of production and sometimes death of the animal. Affected sheep are usually destroyed on the farm, or their carcases are condemned at abattoirs.

Cause

Arthritis in sheep may be caused by a variety of bacteria and viruses. However, the bacterium Erysipelothrix insidiosa is most commonly involved where large numbers of lambs or weaners are affected. Bacteria enter the lambs body through a break in the skin, usually a cut made at mulesing or shearing. They then travel in the bloodstream to the joints, where they multiply and cause damage. Even if the bacteria then disappear, the damage to the joint remains and the swelling so typical of arthritis can be seen.

The Erysipelothrix bacteria can live in the soil for long periods of time. Thus permanent sheep yards and sheep camps are the most heavily contaminated areas on a farm.

During 1992, the following prevalences of arthritis were recorded at Robb Jetty abattoir:

 

Lambs

Rams

Ewes

% of lines of sheep with arthritis

45

48

70

% of sheep with arthritis in the affected lines

1.8

4.0

1.6

 

 

 

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Clinical signs

Signs of arthritis usually appear within several days after the wounding event e.g. mulesing.

Affected lambs are reluctant to move and are quite lame. The infected joints are painful, hot to the touch and swollen. Most commonly the knee of the front legs and/or the stifle of the back legs is affected. Most cases of arthritis persist to the chronic stage, where lameness and stiffening of the limbs result in stunted growth, decreased wool production and sometimes death.

Treatment

In most field situations, by the time the sheep are noticeably lame, treatment is too late to have a chance of success. However, if arthritis is diagnosed early during the course of the disease, treatment with antibiotics may produce reasonable results. The cost of the antibiotics may also prohibit its use in flock sheep.

Prevention

Most strategies aim to prevent lambs or weaners coming into contact with the bacteria.

  • For mulesing, use temporary yards on well grassed areas, well away from existing yards.
  • Lambs should be placed on their feet when released from the cradle.
  • All instruments should be thoroughly disinfected at each break during mulesing.
  • Between animals, soak instruments in disinfectant. Disinfectant is deactivated by dirt or blood and therefore, must be changed often.
  • Use more than one set of instruments so that they have time to become sterilised while in the disinfectant solution. Bacteria may not be killed instantly by disinfectant, especially in the presence of blood or dirt.
  • Injection apparatus must be sterilised by boiling in water before mulesing begins.
  • Needles should be changed at regular intervals so that a sharp, clean needle is used on each lamb.

If significant levels of arthritis persist despite taking the precautions outlined previously, farmers may want to consider using an erysipelas vaccine. The cost of the vaccine may, however, prohibit its use in flock sheep.

To give lambs protection before mulesing, ewes may be vaccinated prior to lambing. If the ewes are being vaccinated for the first time, they should be given two injections, four to six weeks apart, the second one being administered within four weeks prior to the start of lambing. After the initial year, the ewes should be given an annual booster, just prior to lambing.

Lambs may receive their first vaccination at mulesing. Their second injection should be given four to six weeks later, perhaps at weaning. An annual booster will ensure their protection each year. Some farmers may wish to vaccinate the lambs only at mulesing. Field observations indicate some success with this single dose.

see also MULESING - A Farmers view to this cruel 'backstreet' mutilation.

see also - Mulesing, the standard mutilation of Australian sheep

return to Mulesing Index

 
 
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