Dog breeding means practice of mating selected dogs with intention to produce particular qualities and characteristics in offspring. However, this selective breeding has also led to a rise in various diseases.
Selective breeding or close breeding, commonly known as line breeding or inbreeding, results that the number of bad genes in most breeds
exceeds the average number which significantly reduces the genetic variables involved in mating two individual dogs and thereby increases the Coefficient of Inbreeding (COI) which alters the natural defense mechanism of body and finally may lead to various disease manifestations.
Coefficient of Inbreeding (COI)…
This is a mathematical tool that provides a measure of the degree of relatedness of the individuals in any given dog’s pedigree. It is an approximation and not an absolute measure. Individuals with low COIs (less inbred) are more likely to have two different MHC (Major Histocompatabilty Complex) haplotypes. Every individual has a pair of MHC haplotypes which are inherited from each parent.
The immune system…
The immune system is governed by the MHC. This cluster of genes is referred to as a ‘complex’ because of their close positioning on one chromosome. This positioning virtually enables it to be inherited as a unit called a
haplotype. MHC enables the immune system to respond precisely against invading infectious agents like bacteria or viruses. It exists in all species of mammals and not only unique to dogs. MHC genes are exceptionally polymorphic, each having many—sometimes as many as 100—different alleles or forms. MHC complexity is an excellent example of the importance of biological diversity—not only among species but also within them. All naturally reproducing species will avoid or significantly limit inbreeding.
Prone to infections…
Inbred individuals are always homozygous in relation to their MHC genes (i.e. the two sets of identical haplotypes received from parent). This situation diminishes the diversity among MHC and thus body’s capability to mount an effective immune response. Such dogs are more prone to infections and are more likely to suffer autoimmune disease or allergies.
Use of popular sires over several generations can play havoc with MHC diversity. Since any individual can only have two MHC haplotypes, if a significant portion of a breed descends from a relative few number of dogs, the whole population may be threatened. Furthermore, this may lead to poor or ineffective utilisation of vaccines.
Consequences of bad breeding in dogs
- Skin problems
- Immune system disease
- Narrow immune response
- Vaccine inefficacy
- Blood disorders
- Neurological, behavioural and sensory
- Hearing and vision
- Heart disease
- Affecting other vital organs and systems
Things to note
- Close breeding must be discouraged by breeders.
- Avoid the over-use of any individual dog, no matter how fine a specimen he might be.
- No dog affected with chronic autoimmune disease or serious allergies should be bred.
- Breeders should be aware of their dogs’ Coefficient of Inbreeding (COIs).
- Crosses that produce autoimmune disease or allergies should always be discouraged.
- Recording much information as possible on the allergy and autoimmune disease status of numerous relatives of the dogs.
- If screening tests are available for a disease, it should always be used before breeding.
Saving – up to us!
The storm is upon us and we can get rid of it. The potential impact of close breeding on dog’s health is enormously great. Even though we are currently unable to eliminate this kind of problem, damage control must be properly instituted. With good record keeping, diligence and foresight the risk of
producing these costly, potentially devastating, and sometimes-fatal affections can be significantly reduced.
(Dr MK Singh is scientist in Immunology Section at Indian Veterinary Research Institute, Izatnagar, UP).