What Is a Double Merle Dog?

A double merle dog results from breeding two merle-colored dogs together. This can result in blindness and deafness - both of which can affect a dog’s quality of life.

Jan 19, 2024byThalia Oosthuizen
what is a double merle dog

You may not have heard of a double merle dog, but there are plenty of breeds that may end up producing one. Double merles are the result of mixing two merle breeds and, while beautiful, may live a more challenged life. While they’re a rare occasion, it’s good to understand what they are and the health issues they experience.

What’s a Standard Merle?

Australian Shepherd Dog Standing in Grass Field
Image Credit: Bark Post

“Merle” is used to describe a specific coating on certain dog breeds, with a light base coat and splashes of dark patterns across the fur. Several dog breeds may have a merle coat, such as Australian Shepherds, Dachshunds, Great Danes, Chihuahuas, and Border Collies.

Dogs with merle coats are ever-so common, but unfortunately, due to poor education, some people may breed them with other merles without knowing the sometimes-detrimental side effects on the litter.

What Produces Double Merle Dogs?

White Double Merle Dog Lying on Wooden Patio
Image Credit: Reddit

When two standard merle-colored breeds are bred together, a double merle may be produced. They will often have an almost entirely light coat, whereas the parents may have the traditional light coat with darker spots.

If the puppy inherits the merle gene twice from both parents, they’ll be a double merle. The most telling sign will be the coat color, as well as health issues with vision and hearing. Bear in mind that not all pups with a lighter coat will be double merles–they can come in other colors, too.

The Science Behind Double Merles

White Double Merle Dog on Gravel Path with Sunglasses
Image Credit: Positively

The science behind the origin of double merles has to do with genetics. In the same way that human genetics may affect a child, the genes of a merle breed can affect a puppy. We’ve discussed the basics, but let’s break down the genetics.

A double merle is homozygous, meaning it’s inherited two copies of the dominant M gene. This makes its genotype MM, as opposed to a healthy mix of M and that of another non-merle breed. When two merle breeds are bred together, there’s a 25% chance of a puppy inheriting the merle gene twice and making it an MM pup.

White Double Merle Dog Sitting in Lounge
Image Credit: KingPet

In well-practiced and healthy merle and non-merle breeding, one of the merle genes would give the dog that marble color, and the other produces lighter spots throughout the color. When these genes mix, the puppy will lack pigment where it should normally be and will be almost completely one light color. This can then, unfortunately, lead to them being born blind or deaf. They may experience other common health problems, too.

When a merle is bred with a solid color breed, there is no risk of a double merle being produced, only the standard merle. It’s recommended not to breed two merle dogs together, as the effects on a double merle can be hard to watch. If you have a merle and would like to breed it, consider breeding with a non-merle breed.

Health Issues with Double Merle Dogs

Deaf White Double Merle Dog Sitting in Grass
Image Credit: Deaf Dogs Rock

Unfortunately, double merle dogs come with several health issues. It’s essential to be aware of these health concerns, including hearing and vision problems.

Vision problems are a significant health issue found in double merles and can be found in a few different forms. Their vision can range from slightly poor to completely blind, and the eyes will have some visual abnormalities.

Key eye abnormalities to look out for in a blind double merle are:

  • Complete blindness
  • Blown pupils, leading to light sensitivity
  • Microphthalmia (smaller eyes and visible third eyelid)
  • Corectopia (a dropped pupil)

Deafness is another health issue that a double merle will likely live with. While most double merles will be completely deaf, they may only be partially hard of hearing in some cases. Rarely, they may be fine and not suffer deafness whatsoever. If deaf, they will be born that way. Any sudden deafness may be a sign of another health issue.

Ways to Care for a Double Merle

Brown and White Double Merle Dog Lying on Grass
Image Credit: Alpha Paw

All dogs deserve loving homes, and double merles are just an unfortunate result of irresponsible, careless, and greedy breeding practices. If you’re considering getting a double merle, here are some tips for taking care of them.

If your double merle struggles with vision (which they likely will), you should regularly take them to the vet to keep an eye on any deterioration. It’s hard to see dogs suffer, so keeping up to date with checkups is the best we can do for them.

With deafness or poor hearing, there are alternative ways you can train your dog, as opposed to verbal commands. Some double merle owners make up their own sign language to communicate with their dog (very clever!). Others will have physical cues that translate to a command (i.e. a tap on the back for sit).

Can I Adopt a Double Merle?

Double Merle Great Dane Sitting in Garden
Image Credit: Hello Danes

In short, yes. Be aware that shelters may advise you against it due to their health concerns, but if you’re up for the challenge, there’s a lot of value in giving a disadvantaged dog a home. Not all shelters will house double merles, so search in your area to find places that do. To support the welfare of double merles, check out some rescue organizations that you can aid.

If you’re unsure about whether a double merle would make a good fit for your family, consider fostering these dogs first. This way, you can see whether you can meet their special needs and render the appropriate care.

Double Merle Dogs Deserve Homes

White Double Merle Dog in Snow with 2 Kids
Image Credit: Reddit

Double merles are a rare occasion and are often the result of poor breeding or uneducated breeding. If you own a merle, be careful when breeding and do your research. If you’re looking to home a double merle dog, you’re off to a great start by educating yourself on them and their health issues.

Thalia Oosthuizen
byThalia Oosthuizen

Thalia has been a freelance writer for over a decade and a dog (and animal) lover for over 30 years. She grew up on a farm where, at one stage, she had 15 dogs. She currently has one dog, Avery - an adorable pavement special with an extra toe on each foot, and two rescue cats - Boris and Mango. In her spare time, Thalia enjoys running, cycling, swimming, and reading