Years ago, breeders didn’t have DNA testing available to help us identify dogs that were at risk for passing on serious genetic defects. Today, that’s not the case and therefore any reputable breeder will be able to discuss with you the role that DNA plays in their breeding program. Before discussing specific genetic conditions that impact the Yorkshire Terrier breed we want to cover the basics of understanding whether a dog is at genetically clear (healthy), a carrier (healthy but has potential to pass on the disease to puppies when bred to another carrier) or affected (unhealthy and will pass on the disease).
CLEAR – This is the gold standard. This is a dog who is clear of any genetic defects. This means they are not personally at risk and do not carry any genes for genetic defect that can be passed on to their puppies.
CARRIER – A carrier is a dog who carries one (1) gene for a genetic defect. Because they only carry one gene for this defect it will not affect them (they will never develop the defect) but they can pass it on to their puppies. Some consumers mistakenly believe that carriers should not be bred but this is not case. Carriers can safely be bred but only to a dog who is clear for that defect. If we removed all carriers from our breeding pool we would encounter other problems with inbreeding. However, two carriers should not be bred.
AFFECTED – A dog who is at risk (or affected) is a dog who carries 2 copies of the gene for a trait and therefore is at risk for the disease. Although not ideal, this dog can still be bred to a dog who is clear as they will produce a litter of carriers. That being said, you do not want to purchase a dog who is affected for a genetic condition as that dog will likely become symptomatic of that condition. We choose not to breed any dogs that are affected, if any pups we purchase for breeding has an Embark come back affected the pup is rehomed to a pet home. If your breeder doesn’t test genetically then you will have no way of knowing what you are getting.
This diagram helps illustrate the breeding of clear, carriers and affected dogs.
