The Genetic Link to Cancer
This is Kali in 1997. She died May 5, 2003 of Hemangiosarcoma. So did her brother, Czar, in 2004 and her sister, Bailey, in 2006. The Kali’s Wish Cancer Foundation is funding research into the role genetics plays in many cancer cases, particularly as it relates to certain pre-disposed breeds.
There is a lot of speculation about the causes of the epidemic rates of cancer in our dogs today. One area that warrants in-depth research is breeding practices. With cancer types and rates varying dramatically by breed, and as high as 87% in popular breeds such as the Golden Retriever, there is compelling evidence pointing towards a genetic link to cancer. It is estimated that the average cancer rate of all breeds is now over 50%, meaning half of all dogs will develop cancer.
There are three breeding philosophies subscribed to by the majority of breeders, which are:
In-Breeding – the mating of two dogs that are closely and immediately related. This includes brother-to-sister, father-to-daughter etc.
Line-Breeding – the mating of two dogs that are two or three generations apart. This includes uncle-to-niece, half-brother-to-half-sister or grandmother-to-grandson.
Out-Crossing – the mating of two dogs of the same breed that are unrelated. The Inbreeding Coefficient (I.C.) of the puppies is lower than the average of the parents. The I.C. is a mathematical model for the definition of the level of inbreeding in a dog.
In-breeding and line-breeding are known to gain rapid results when breeding for a certain desired trait. However, when you double up on the genes to gain good traits, you are also doubling up on the genes that produce bad traits. These bad traits can be unseen genetic defects that have not, or cannot yet be tested for. When two bad genes are doubled up due to inbreeding or linebreeding, they suddenly become a dominant trait likely to manifest itself in the pet.
There is considerable debate on what diseases are genetically linked, but it is becoming apparent to many around the world that the high rates of cancer, diabetes, allergies, epilepsy and other all too common conditions may be the result of in-breeding and line-breeding.
In many parts of the world, national kennel clubs have opted to ban in-breeding and line-breeding. However, line-breeding is still the favored approach for breeders in North America. The Canadian Kennel Club has stated the following:
“The relationship between the Sire (father) and Dam (mother) of the litter has no bearing on registration eligibility. Breeding dogs that are closely related can fix certain characteristics, both desirable and undesirable. However, there is no rule that prohibits inbreeding and line breeding; this is left to the discretion of individual breeders.”