AFBI warns about the risk of chronic copper poisoning in sheep

AFBI would like to make flock owners aware of the risks of chronic copper poisoning, this condition can be seen throughout the year but particularly in summer and autumn after prolonged concentrate feeding of ewes in lactation, concentrate feeding to rams and lambs for sale, coupled with stress associated with sales are risk factors for the disease.

The changeable weather we are experiencing is also a risk factor for the disease.

While copper is an essential part of enzymes governing many biological functions, sheep are particularly susceptible to the toxic effects of excess copper. Toxicity is most frequently observed in the Charolais, Texel and Suffolk breeds, and less frequently observed in the mountain breeds.

Clinical disease follows a period of excess intake and occurs when the liver’s capacity to store excess copper is exceeded and there is a sudden release of copper by the liver. This typically occurs after weeks or months of accumulation of copper and often coincides with a period of stress on the animal. The sudden release of copper by the liver causes haemolysis and irreversible damage to the kidney and the brain. Copper poisoning is slow to develop but sudden in onset. The eyes and skin become jaundiced and post mortem examination reveals an orange liver, black kidneys and red/brown urine. Biochemistry results show a toxic level of copper in the liver and the kidney. Serum copper levels do not provide a reliable warning of imminent toxicity.

While blood tests for liver enzymes can assess how much damage has occurred to the liver these tests are not specific for copper toxicity and liver damage can be due to other conditions such as the presence of parasites.

Feeding concentrates containing high levels of copper and excessive administration of copper containing mineral supplements or boluses are typical scenarios in which cases of copper toxicity in sheep may develop. However, even a diet with an acceptable copper concentration can also cause subclinical toxicity if fed for long enough to vulnerable breeds. This is because copper is a cumulative poison with the combination of daily exposure and prolonged feeding playing a part. Every opportunity to reduce the concentrate intake between lactations should be taken. Particular care should be taken with rams as they are usually fed concentrates more regularly and for more prolonged periods. The best way of managing this condition is to minimise long term concentrate use in the diet.

Treatment options exist but they are only effective in the early stages of the clinical disease and are not always effective. Contact your local vet for advice if you are concerned about copper poisoning. 

If you would like a post mortem carried out on a suspect case, this can be undertaken at our Stormont or Omagh laboratories but should be arranged via your local vet who can advise on carcase submissions.

Notes to editors: 

AFBI’s Vision is “Scientific excellence delivering impactful and sustainable outcomes for society, economy and the natural environment”.

AFBI’s Purpose is “To deliver trusted, independent research, statutory and surveillance science and expert advice that addresses local and global challenges, informs government policy and industry decision making, and underpins a sustainable agri-food industry and the natural and marine environments”. 

AFBI’s core areas:

• Leading improvements in the agri-food industry to enhance its sustainability.
• Protecting animal, plant and human health.
• Enhancing the natural and marine environment.

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