When it comes to breeding dogs, linebreeding is just one category to depict several types of crosses. Also referred to as inbreeding, the practice of linebreeding dogs may have some advantages and disadvantages. When considering linebreeding, the breeder must be very careful on carefully evaluating the pros and cons of this method of breeding. While dogs do not show any moral objections to linebreeding, and most registries including the American Kennel Club allow it, breeding without keeping in mind the disadvantages that come with linebreeding, may lead to serious problems down the road.
What is Dog Linebreeding?
Linebreeding is a form of inbreeding. While the two terms are often used interchangeably, linebreeding may be used in particular to depict the crossing between individual dogs and their descendants.
Linebreeding may include breeding dogs that are very closely related such as mating related dogs such as mother dog to son, father dog to daughter or brother to sisters or more distantly related dogs such as cousins.
The opposite of linebreeding is outbreeding, also known as outcrossing, but a clear definition is yet to be made as to how far out a relationship must be to make a distinction between linebreding and outbreeding.
Generally speaking, linebreeding is considered the crossing of dogs having one or more common ancestors on one or both sides and in the last five generations.
Did you know? Linebreeding became particularly popular in the 1950's following Lloyd Brackett's breeding of German shepherds.
Advantages of Linebreeding
Linebreeding may come handy when there is a shortage of dogs and a limited gene pool.When a new dog breed is created because of an attractive mutation, the gene pool is initially small which causes the need for mating closely related dogs. In the wild, animals like wolves may linebreed when they are isolated from other wolf packs. However, in a domestic setting, linebreeding dogs may be specifically used for attaining a particular trait and maintaining uniformity through several generations. So the advantages of line breeding are an increase in uniformity and a better ability for offspring to pass on and "fix" desired traits. While there are some advantages in linebreeding, there are several disadvantages.
Disadvantages of Linebreeding
Linebreeding might not necessarily cause particular problems in the first generation, but problems may be encountered over time as the gene pool remains too small. A too small gene pool may contribute to an increase in problems such as lower "vigor," smaller litters, high mortality rates, lowered immune systems and an increase in genetic diseases. This is why zoos must often borrow animals from other zoos so to attain better genetic diversity.
Did you know? Royal families of the 18th century Europe practiced inbreeding for the purpose of keeping their royal blood pure. This resulted in inherited disorders such as mental illnesses, bleeding disorders, and cancer in youngsters. Interestingly, these problems occurred even though their inbreeding consisted mostly of intermarriage between cousins rather than more closely related kinship such as sharing one parent the same," explains Dr. Roger L. Welton
A Closer Look
Whether linebreeding will result in more advantages or disadvantages depends on how the genes line up. One may end up with a double dose of good genes or a double dose of bad. But let's see a quick example to have an idea.
For example, let's imagine for a given breed that G is the good trait and B is the bad. Both closely related dogs have both the G and B genes. When these dogs are mated, the GB is split and each pup will get one gene from each parent. This can lead to a winning combination of GG which is great, while some may get BB which is bad. Most pups will have obtained GB though which makes them just like the parents. When it comes to statistics, the pups therefore have a 1 in 4 chance of having GG or BB and a 1 in 2 chance of having GB.
When linebreeding, the breeder must therefore carefully examine the past three generations for undesirable problems considering that a small gene pool increases the chances for a recessive gene for an undesirable trait such as jaw conformation problems, skin diseases, heart murmurs or any reproductive difficulties to pop up. Because of these risks, breeding closely related dogs is best if left to professional experienced breeders or avoided altogether.
The Bottom Line
When it comes to breeding methods, linebreeding is a double-edged sword. While linebreeding can help fix certain traits and improve type, excessive linebreeding causes a tighter gene pool which leads to loss of vigor and higher chances for undesirable traits and health problems to crop up.
- Dog Breeding, Whelping and Puppy Care, By Gary England, Wiley-Blackwell; 1 edition (December 26, 2012)