The

AIREDALE  TERRIER  HEALTH  FUND

Collecting DNA samples 

Why should I have my dog DNA profiled?

 We need to have DNA samples in order to be able to identify mutant genes, inherited diseases are caused by mutant genes.

The tests are based on a small amount of DNA prepared from tissue taken from an individual dog. Ideally blood tissue will be used, this DNA sample will contain all the chromosomal material, and hence all of the genes, present in that individual.

The DNA will then be screened to see if it contains no copies, one copy or two copies of a particular mutant gene. For a disease known to result from a single recessive mutation, if no mutant copies are present, the animal is clear, if one copy is present the animal is a carrier and if two copies of the mutant gene are present it will be affected.

What if my Dog has a DNA profile?

If your dog has a DNA profile recorded that was taken from a swab, we would still like to have a blood sample if it is or intended to be a breeding animal.

Who should send samples?

It is hoped that all breeding stock will at least have a DNA profile, and if possible a blood sample stored in the blood bank.

How can this be applied to breeding programs?

Being able to identify carriers will have an immense impact on breeding programmes which will be able to be designed to reduce the frequency of the mutant gene in the breed. If possible, carriers can be removed from the breeding stock, thereby preventing them passing on their mutation to further generations.

However, DNA technology offers far more than this. (In fact, carriers can be identified from traditional pedigree analysis without sophisticated DNA tests and removed from the breeding stock.) Removal of carriers from breeding stock may not be the ideal solution because, although you are minimising the spread of the mutant gene, you may also be removing positive qualities that the breed requires in order to maintain its overall health; in other words, you could be throwing the baby out with the bath water.

The availability of a DNA test allows much more subtle manipulation of breeding programmes to reduce the frequency of a particular mutation whilst retaining some of the positive features present in affected lines. For example, let’s say that we have been

able to identify a carrier bitch using a DNA test. Rather than simply removing this bitch from the breed’s pool of breeding bitches, we can screen potential mates and identify a dog that is clear of the mutation. If the clear dog and carrier bitch are now mated, approximately half of their offspring will be carriers and the other half will be totally clear of the disease gene, so there will be no clinically affected dogs in the litter. However, we can go one step further; by DNA testing the Reality can be different. In principle, if you flip a coin it has50% chance of coming down ‘heads’ and 50% chance of coming down ‘tails’; in reality you often get runs of either ‘heads’ or ‘tails’. So, the proportion of offspring in individual litters could differ from the expected outcomes given above. Progeny, we can identify the carriers and the normals. Once identified, the normals can then be bred on thereby removing the mutant gene from the population, but at the same time retaining many of the positive features that the line has to offer.

Collecting the blood samples

Blood samples will be taken by your Vet, it is suggested that the sample be collected as part of a general health check, or any other occasion when blood is being drawn.

The completed submission form, a 5-generation pedigree and any health certificates available should accompany the sample.

The blood samples will be stored by the Animal Health Trust, when a sample is received the DNA profile is extracted and recorded. The DNA profiling scheme is jointly run with the Kennel Club, who will issue a certificate to the owner to confirm testing has been completed, and that a DNA profile is recorded.