Merle Genes in Dog Breeding
What is merle?
In dogs, "merle" is a pattern of coloring that can appear in the coats of certain breeds. The merle gene causes irregularly shaped patches of solid color to appear amidst a background of a different color. The patches can be any color, but are most commonly shades of blue or brown.
The merle gene is considered a dominant gene, which means that if a dog inherits the gene from one of its parents, it will express the merle coat pattern. However, the expression of the gene can be influenced by other genes and can vary greatly between individuals. Some dogs may have a very distinct merle pattern, while others may have a more subtle pattern.
Merle can affect the skin and eyes, as well as the coat. The eyes of a merle dog can be affected, with some having one or both eyes that are blue or have a blue sector in the iris, this is often called "merle eye". Also, the dog can be born deaf or with partial hearing loss if both ears are affected by the merle gene.
Not all dog breeds have the gene that causes the merle coat pattern. Some examples of breeds that can have the merle coat pattern include the Australian Shepherd, the Collie, and the Shetland Sheepdog.
Why merle?
The merle coat pattern can be highly sought-after in dogs because it is considered to be a unique and attractive feature. The irregular patches of color can create a striking and distinctive appearance, which can make a dog stand out in a crowd. Additionally, the merle coat pattern can come in a wide variety of colors, which can further add to the dog's overall visual appeal.
Another reason why the merle coat pattern is sought-after is that it can be rare, or not standard, in certain breeds. Some breeds that can have the merle coat pattern are relatively uncommon, and as a result, merle-coated dogs of these breeds can be quite hard to come by. As a result, some people may be willing to pay a premium for a dog with a merle coat pattern.
💡 In certain breeds the merle coat can be a disqualifying fault or the result of dishonest outcrossing.
However, it's important to be aware that breeding for the merle coat pattern can also lead to health problems if breeders do not do their due dilligence in learning about the mutation. Double Merles (a dog with two copies of the merle gene) can be more likely to have hearing or vision problems, or other health concerns. So it's important to be aware of this risk if you are considering breeding or purchasing a merle-coated dog.
Breeding merle
Dog breeders should be aware of several important factors before breeding dogs with the merle gene.
First, it's important to understand that the merle gene is a dominant gene. This means that if a dog inherits the gene from one of its parents, it will almost certainly express the merle coat pattern. However, the expression of the gene can be influenced by other genes and can vary greatly between individuals. As a result, it can be difficult to predict the exact appearance of a dog's coat when breeding for the merle pattern.
Secondly, as mentioned above in this article, breeding two dogs that carry the merle gene can result in "double merle" puppies, which are born with two copies of the merle gene. These puppies are more likely to have hearing or vision problems, as well as other health concerns. This can be avoided by breeding two non-merle dogs together or one non-merle dog with one merle dog. Additional genetic testing is always recommended with merle breedings to ensure that you understand the alleles you are dealing with and potentially passing on to puppies.
💡 In rare cases the merle gene is inherited but not expressed, so genetic testing is paramount in identifying whether a breeding dog carries this gene.
Finally, it's important to be aware that breeding for the merle coat pattern can be controversial, as it can lead to health problems for the puppies if breeding pairs are not selected carefully. Therefore, it's important to be fully informed about the risks and to carefully consider the potential health and welfare implications for the puppies before breeding dogs with the merle gene.
Pros & Cons
Some of the potential pros of breeding dogs with the merle gene include:
The merle coat pattern can be striking and attractive.
It can create unique color variations within a breed.
Some of the potential cons of breeding dogs with the merle gene include
The merle gene is associated with a number of health problems, including deafness, blindness, and organ defects.
Breeding two merle dogs together can increase the chances of producing puppies with severe health problems.
The merle coat pattern is a disqualification in some breed standards.
Adding the merle gene to your program can be a fun way to bring a splash of color into your gene pool. It's always recommended to consult with a veterinarian and a geneticist before breeding any dog, this way you can make the best decision for your breeding program and ensure that you are producing healthy puppies.
