Copper Toxicity in Horses: Does it Exist?
Authors: Belli Carla Bargi, Fernandes Wilson Roberto, Torres Luciana Neves, Sucupira Maria Claudia Araripe, de Sá Lilian Rose Marques, Maiorka Paulo Cesar, Neuenschwander Henrique Macedo, de Barros Aline de Matos Curvelo, Baccarin Raquel Yvonne Arantes
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Copper Toxicity in Horses Copper toxicity has long been considered exceptionally rare in equine practice, yet a cluster of cases emerging across multiple Brazilian properties prompted investigation into the condition's actual prevalence and aetiology. Researchers documented five clinical cases affecting at least 20 horses total from geographically distinct locations, conducting thorough physical examinations, laboratory analysis (including serum copper levels, haematology and liver enzymes), feed and soil copper quantification, and histopathological examination to establish diagnosis. All affected horses presented with hemolytic anaemia, hemoglobinuria and Heinz bodies, alongside elevated aspartate aminotransferase and gamma-glutamyl transferase; two died acutely whilst the remainder responded variably to supportive care and blood transfusion, though one required eventual euthanasia due to recurrent complications. Notably, two horses experienced multiple relapses over months—an atypical pattern for copper toxicity—and contamination was traced to poultry litter used as pasture fertiliser or copper-based crop treatments on the same or adjacent properties. The findings suggest that copper toxicity warrants inclusion in differential diagnoses for equine haemolytic crises, particularly in regions using poultry by-products for soil amendment, and that preventive measures should address both dietary copper balance and pasture management practices to mitigate environmental exposure.
Read the full abstract on PubMed
Practical Takeaways
- •Include copper toxicity in your differential diagnosis list for horses presenting with hemolytic anemia and hemoglobinuria, particularly those with access to pastures fertilized with poultry litter or near copper-treated crops
- •Assess pasture soil copper levels and feed copper content in horses showing unexplained hemolytic disease; sources may include agricultural inputs on or adjacent to grazing properties
- •Implement preventive measures including pasture management protocols, verification of copper levels in fertilizers and pesticides, and dietary copper monitoring to prevent toxicity in susceptible horses
Key Findings
- •Five cases of copper toxicity were identified across 4 properties affecting at least 15 horses total in Brazil
- •All affected horses presented with hemolytic anemia, hemoglobinuria, Heinz bodies, and elevated liver enzymes (AST and GGT)
- •Copper toxicity sources included poultry litter soil fertilization and copper-containing pesticide residues from neighboring crops
- •Two horses died acutely; three horses survived with clinical management including blood transfusion, though one required euthanasia due to complications; recurring episodes over months occurred in two horses, which is atypical for equine copper toxicity