Cattle are commonly supplemented with copper to prevent copper deficiency (often due to molybdenum toxicity). Unlike sheep, which are very prone to copper poisoning, it has been thought that cattle are relatively resistant. In the past most cases of copper poisoning have been associated with cattle inadvertently eating pig food or grazing pastures fertilised with pig manure (pigs are fed high levels of copper to increase growth rates). However, cases of copper toxicity are now being seen in cattle with no connection to pigs or pig by-products.
Copper toxicity in cattle is usually chronic in development (occurring as the result of a build–up over a long period of time), but is usually seen as an acute disease. The signs occur as the result of liver failure when the level of copper stored in the liver gets too high and damages the liver cells it is stored in)
Clinical Signs
- Depression
- Colic (abdominal pain)
- Paleness and jaundice (yellowing)
- Reduced appetite and milk yield.
- Dark red urine (haemoglobinuria)
- Death
Diagnosis
On clinical signs noted above you can be suspicious of copper poisoning. However your veterinary surgeon would carry out further tests to confirm copper poisoning:
- Blood copper – will be elevated in ill animals, and in many apparently normal animals (unless there is a single small point source of copper. Blood copper measurement will show the extent of the problem
- Tissue copper: Measurement of liver and kidney copper is confirmatory. This can be done by biopsy, but is best done post-mortem.
Treatment
Identify dietary sources of copper, and if possible remove them. Remove copper from all minerals. Individual treatment with ammonium molybdate and sodium thiosulphate can be effective but may not be economic. Other supportive therapy such as fluid therapy and antibiotics is of limited value
Prevention
It has not yet been clearly established what the cause of the increased rate of copper poisoning in cattle is. However, the risk of copper poisoning can be reduced by
- Ensuring you know what the copper intake of your cows. Pay particular attention to the copper content of your mineral and your forage
- Using chelates with care. So-called ‘organic copper’ may be better absorbed than inorganic copper, but this increase the risk of copper toxicity, particularly if the same amount of copper is fed.
- Do not supplement with copper unless you have clear evidence of copper deficiency (or molybdenum toxicity)