Merle dogs are often spotted: sometimes more bluish, sometimes more reddish. Sometimes they even have two different eye colors. Many breeders and keepers like this. But the gene that creates this spotting also carries risks.
Many don’t know what they are doing when they just start breeding and breed exactly two Merle gene carriers with each other just because the ‘colorful dogs’ are currently in fashion,” warns animal psychology consultant Ingrid Blum. The merle gene is responsible for part of the pigmentation on hair and skin and lightens the body pigment eumelanin. As a result, it creates a very special coat pattern in which black appears as gray and brown as red, referred to as so-called “Blue Merle” and “Red Merle”. Sometimes whole parts of the body are white. The eyes can be brown, blue, or mixed colors, with dogs that have one blue and one brown eye as well as those that combine both colors in one eye.
However, the merle gene is also considered an enzyme defect, since it can lead to serious diseases of the eyes, hearing, and other organs if two merle carriers are mated with each other during breeding. Statistically, 10 percent of such homozygous animals are deaf in one ear and 15 percent are deaf in both ears or even blind. Some dogs don’t even have eyes.
The Defect is Not Always Recognizable
Many Merle dogs die before they are sexually mature, show less zest for life and develop more slowly. Some male dogs also lose fertility and suffer from balance problems. Animal rights activists and many other experts such as Blum, who runs the Fee dog school in Hämikon-Berg LU, therefore advise against such breeds.
The merle factor can be found in breeds such as Shelties, Collies, Border Collies, Bobtails, Beaucerons, Pyrenean Shepherds, Australian Shepherds, Dachshunds, Great Danes, Cocker Spaniels, and Chihuahuas. In the case of the latter, there are already breeding bans for Merles. However, the popular little ones are particularly at risk, as many are bought online from abroad and the suppliers usually have little idea of the merle factor and genetics.
You also have to be careful with all other breeds, because the common thing is that the defect is not always recognizable. It gets tricky, for example, with sable-colored, i.e. naturally reddish, dogs. Therefore, according to Blum, no Sable dogs can be mated with Merle gene carriers in Collies, for example. “A Sable can definitely carry the Merle gene. Most of the time you can see the Merle markings on newborn puppies, later it is difficult or impossible to see with the naked eye,” explains the specialist. It can also happen that only some of the puppies in a litter are affected.
Health Check Before Buying
Anyone who is still interested in such spotted dogs or even wants to breed with them should not shy away from a certain amount of effort and have the animals put through their paces in good time. With a bit of luck, there are no diseases. You should also take a close look at the pedigree papers before buying. If there are no papers at all, special caution is required.
To find out whether a dog is actually a carrier of the merle gene, you can have a blood test or a buccal swab done by the veterinarian. All of this is advisable before you fall in love with the puppy’s eyes, says Ingrid Blum. “It’s worth choosing breeders with care and finding out for yourself.”