Are merle dogs unhealthy?


Are merle dogs unhealthy?

Merle dogs of all kinds are beautiful, unique and fascinating. But are they healthy dogs as well? Are any inherent conditions associated with the merle coloring?

Many dog owners have heard before that merle dogs are unhealthy and have vision and hearing issues. Is that true? Does it depend on which kind of merle pattern the dog has? The quick answer is that a well-bred merle dog with one copy of the merle gene will be as healthy as a solid-colored dog. If a dog is a so-called “double merle” however, he is likely to suffer from vision, hearing and skin problems.

Let’s look in detail at the heath issues associated with the merle gene!

Table of Contents

Can merle dogs be as healthy as other colors?

Yes – merle dogs can be just as healthy as dogs that have a solid color. They have the same life expectancy, they are just as strong and athletic and smart as their counterparts without the merle gene.

In lines with responsible merle breedings, all offspring will be healthy and live a long life.

What makes merle dogs’ health problematic?

Health problems occur when a so-called “merle-to-merle” breeding occurs. Some irresponsible breeders do this in order to produce more merle puppies. 

In responsible breedings, a solid colored dog is paired with a merle dog. The offspring will be 50% merle and 50% solid.

Some breeders want to produce more merle dogs as they are more desirable and can be sold for a higher price. They pair two merles together. This pairing produces 1/4 solid dogs, 1/2 merle dogs and 1/4 double merle dogs.

Double merles – a lot of health problems

Double merles are easily recognized by their very light complexion. They have a lot of white, and lack pigmentation on their nose and around their eyes. Here is an examples of a double merle dog:

double merle

The extreme lack of pigmentation is what makes these dogs unhealthy and prone to multiple conditions. It goes along with:

  • Hearing impairment – ranging from light deficits to complete deafness
  • Vision impairment – up to complete blindness
  • Microphthalmia: a rare condition causing very small eyeballs that sometimes have to be removed
  • Skin cancer, due to the lack of pigmentation and no protection from UV light

Double merles can have varying levels of these conditions. Some dogs are stillborn or pass away soon after birth. Some fail to thrive and never reach the quality of life of their littermates.

Others are able to live fairly normal lives, reaching the full size of their breed, being able to go for walks, learn tricks or even participate in dog sports.

double merle great dane

Due to not hearing and seeing well, these dogs tend to have problems in social settings. They often cannot communicate appropriately with other dogs, cannot be off-leash because they don’t have a good recall and struggle with fear and anxiety.

Their limited vision and hearing causes them to often be startled and surprised. Owners have to take a very careful approach to training these dogs to show them that the world is a friendly and predictable place.

Is the merle gene bad?

As long as a dog only has one copy of the merle gene, this is not bad or unhealthy at all. The problems only arise when a dog has two copies of the merle gene and is a double merle – then he will experience an array of health issues.

Many extremely healthy, athletic and smart dogs are merle, such as many dogs in dog agility. Some merle dogs have even won the Agility World Championship – definitely a sign that the gene are not unhealthy or bad!

A difficulty in breeding merles is that certain colorings might hide the merle pattern, leading to accidental merle-to-merle breedings. E.g. in Border Collies the rare color ee red/gold hides the merle pattern. Dogs appear to not be merle, but genetically they can be. If such a dog is crossed with another merle dog, this could be an unwanted merle-to-merle breeding, with the unfavorable results of double merle puppies.

double merle border collie breeding unhealthy

The bottom line

A dog with a single copy of a merle gene is not less healthy than his solid-colored relatives. Double merle dogs however are very different – they are highly impacted by their two copies of the merle gene. 

Some puppies are stillborn and do not survive the first weeks of life. Others are able to reach adulthood, but suffer from vision and hearing issues and have a strong tendency to develop skin cancer. The extreme lack of pigmentation that is seen in these dogs is not healthy – and double merle breeding need to be avoided by all means.

In some breeds, merle can be present even if it is not visible (such as in the ee red color in Border Collies). In this case, dogs should have genetic testing done to determine whether only one of them has the merle gene.

Unfortunately, some breeders strive to breed merle dogs for financial reasons. They often do not do health-testing on the parents or even breed dogs with known issues in their lines (such as epilepsy). This is especially prevalent in “high demand merle dog breeds”, such as merle Pitbulls or Fluffy Frenchies.

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