DNA testing for copper toxicosis in Bedlington terriers.

Copper toxicosis is an hereditary disease in which failure of the liver to expel dietary copper leads to a build-up of this toxic metal causing illness and death. It is inherited as an autosomal recessive trait. As such, two copies of the defective gene, one inherited from each parent, need to be present before an individual displays clinical signs. Dogs with one copy of the defective gene and one copy of the normal gene (carriers), will not show clinical signs, but will be able to transmit the defective gene to their offspring. A reservoir of symptomless carriers exists in the population and when two carriers are bred, affected dogs may be thrown up in the litter. Unlike liver biopsy, DNA testing has the potential to pick out carriers as well as affected dogs so that all dogs bearing the defective gene can now be identified and the disease gene eventually eradicated from the population.