Inbreeding is inevitable if one wishes to preserve the desired traits in a breed. In fact, many pedigree dogs that we see nowadays are likely to have been the product of inbreeding. All of the popular dog breeds that were bred under the breeding standards have some history of inbreeding. It may have contributed as much in the establishment of the pedigree breeds; however, this comes with a cost.
Why opt for inbreeding dogs?
Inbreeding is a viable option to preserve the desirable characteristics of dogs. Establishing a new breed, whether it is desired for its record of temperament, looks, or certain adeptness in working activities (such as guarding, herding, or retrieving), is to undergo breeding selection. For instance, the mating between two dogs resulting in a unique pooch that is set apart from other dog breeds can be a good time to propose a new breed standard. This results in a need of producing more dogs that have the desired traits from the original dog or dogs to increase the gene pool. The main objective is to maintain the prevalent mutation and the dominant gene within the breed. Whilst outcrossing breeds can also be done to prevent inbreeding, it somehow defeats the purpose. Outcrossing leads to a decrease or a dilution of desirable traits in the offspring.
The consequence of inbreeding in dogs
Can you breed a mother dog with a son? How about a father dog with a daughter? Regardless of the subjects involved as long as it is inbreeding, the risks are all the same.
Inbreeding causes problems due to the recessive genes that can be potentially inherited from both the sire and dam. This greatly affects pups when two parents have recessive genes or when they are closely related to each other.
Further, inbreeding could cause a list of potential hereditary conditions and health issues that may or may not show in the pup’s early years. Hip and elbow dysplasia and patella are just some of the conditions that can be potentially inherited. In addition, there is also inbreeding depression to be worried about. What is inbreeding depression? This is a result of the inbreeding that may manifest in an overall deterioration in health, reduction in litter size, fertility, a shorter lifespan, and others.
In summary
Here are the advantages and disadvantages in quick bullet points:
Advantages
- Increased uniformity
- Chances of passing on traits to offspring
- The capacity to engineer desired traits and breed type
Disadvantages
- Birth defects
- Fewer offspring
- Likely to have genetic diseases
- Lower fertility rate
- Smaller size
- Weak immune functionality and shorter lifespan
The coefficient of inbreeding (COI) in dogs
The higher the degree of inbreeding, the higher the risk in a dog’s health. As such, it is important for breeders to know the degree of inbreeding to help decide if whether it is good or not to breed the particular dogs. There are now dog inbreeding calculators available on the internet, but here is a rough guide on the common COI statistics:
- 25% from father/daughter
- 25% from mother/son
- 25% brother/sister
- 12.5% from half-brother/half-sister
- 12.5% from grandparent/grandchild
- 6.5% from first cousin/first cousin
- 6.5% from great grandparent/great-grandchild
When the COI is higher than 6.25%, it is usually considered unfit to be an establishing breed as it is likely to have hereditary defects or problems. However, it is also important to acknowledge that COI is only a statistical analysis and therefore should not be used as a direct assessment.
Health issues from inbred dog breeds
It is believed that an outcross between two unrelated genetic pools is healthier, with a longer lifespan. With purebreds, especially inbreds, there is a long list of inherited genetic health disorders that are particular to some. The common causes are the following:
- Hip and elbow dysplasia Affected dogs will suffer from both pain and disability. This is due to the deformed structure or the abnormal growth that ends with malformations. Breeds predisposed to suffer from hip dysplasia:
Breeds predisposed to suffer from elbow dysplasia:
- Heart disease Affected dogs may suffer from any heart problems, which include dilated cardiomyopathy, coronary artery vasculitis, and aortic stenosis. Breeds predisposed to heart diseases are as follows:
About 30% of purebreds are likely to have inherited eye complications, including glaucoma, progressive retinal atrophy, and others, which may lead to partial or absolute blindness. Breeds predisposed to eye problems are as follows:
