VetGen - The leader in veterinary genetic disease research and genetic disease detection services for purebred animals

Breeds Serviced

  • Bedington Terrier

Copper Toxicosis (CT)

Canine copper toxicosis ("CT") is an autosomal recessive disorder of copper accumulation which results in severe liver disease in several dog breeds. Unless specific anti-copper treatment is instituted, most affected dogs die at three to seven years of age. CT is, in particular, a severe problem in Bedlington Terriers. The frequency of CT in Bedlingtons is significant enough to be a major health concern. Affected dogs may be definitively diagnosed by invasive liver biopsy, but this technique cannot identify CT carriers. Therefore, CT carriers continue to be bred, creating extreme difficulties for responsible Bedlington breeders and owners who wish to halt the perpetuation of the disease.

Initially a linked marker test was developed as an aid to breeders, and more recently a direct test was developed that identifies a type of mutation known as a deletion. This particular deletion eliminates a major section of a copper metabolism gene, Commd1. This deletion test identifies the overwhelming majority of disease causing alleles.

CT Deletion Test

The discovery of a deletion in the Commd1 gene provided the basis for a direct test for the likely major cause of CT in Bedlington Terriers. This mutation was identified independently my multiple research groups and verified by others. The Commd1 gene encompasses a region of canine chromosome that also includes the previously available linked marker test. Information on the correlation of the deletion test and the marker test can be found below, but the gist of the matter is as follows:

  • The deletion in Commd1 seems to be responsible for > 95% of CT in Bedlington Terriers.
  • All deletions are linked to a marker type 2, but not every marker 2 is linked to a deletion.
  • All dogs with two copies of deletion are affected, and all dogs with one copy are carriers, at least.

Occasional dogs with no deletions are now known to have copper toxicosis, both in North America and Europe. The frequency of this is very low, probably less than 5%. Research is continuing into the cause of this second form of CT.

Result Types

CLEAR: the dog has 2 copies of the normal gene and will neither develop copper toxicosis caused by the known deletion in the COMMD1 gene, nor pass this mutation to its offspring.
CARRIER: the dog has one copy of the normal gene and one copy of the mutated COMMD1 gene. It will not develop copper toxicosis caused by this mutation but if bred from will pass on the mutation to (on average) 50% of its offspring.
AFFECTED: the dog has 2 copies of the mutant gene and has copper toxicosis.
Male Clear of COMMD-1 Deletion Male Carrier of one copy of COMMD-1 deletion Affected Male
Female Clear of COMMD-1 Deletion 100% Clear 50/50 Carrier/Clear 100% Carrier
Female Carrier of one copy of COMMD-1 deletion 50/50 Carrier/Clear 25/50/25 Clr./Carr./Affctd. 50/50 Carrier/Affected
Affected Female 100% Carrier 50/50 Carrier/Affected 100% Affected

Ideal Breeding Pair - Puppies will not have the disease gene (neither as Carrier nor as Affected).

Breeding Is Safe - No Affected puppies will be produced. However, some or all puppies will be Carriers.Accordingly, it is recommended that Carrier dogs which are desirable for breeding be bred with Clear dogs in the future, which will produce 50% carrier and 50% clear animals, to further reduce the disease gene frequency. These offspring should be tested by VetGen's test for this defective gene, and if possible, only the clear animals in this generation should be used.

High Risk Breeding - Some puppies are likely to be Carriers and some puppies are likely to be Affected. Even though it is possible that there will be some clear puppies when breeding "Carrier to Carrier", in general, neither this type of breeding pair nor "Carrier to Affected" are recommended for breeding.

Breeding Not Recommended - All puppies will be genetically and medically affected.