General description
  • There are many different types of cancer (malignant tumour) that can affect livestock; however most are rare.
  • The most common sheep cancers in Australia affect the skin and eyes and are caused by the sun's ultraviolet radiation irritating exposed areas of the skin. But cancer can have other causes and affect other organs too.
  • If malignant tumours are found in animals slaughtered at abattoirs, all or part of the carcase may be rejected.
  • Sheep that have been badly mulesed, or had their tails docked too short are predisposed to cancers.
  • Sun damage to bare areas of unpigmented skin plays a large role.
Clinical signs
  • Skin cancers begin as red, sun-damaged patches.
  • As the tumour grows it may cause severe irritation and distress to the animal.
  • Diagnosis is confirmed after microscopic identification of the tumour tissue.
  • A veterinarian can successfully treat early stages of some cancers by surgically removing the affected area and/or treating it with cryosurgery (freezing) or radiation.
  • Sheep with cancer may have adverse welfare. Badly affected sheep should be euthanised.
  • Leaving skin on top of the tail during the mulesing operation and permitting tail length to extend to the tip of the vulva will offer some protection.
  • Some lines of sheep may be more prone to cancer. Consider culling affected animals from the flock if you experience excessive rates of cancer.
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