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Dog Health 15.03.2021

Merle - the special color in certain dog breeds

Johann by Johann, Johann has been a dog dad since 2018 and a dog fan since 1986.

The merle factor in dogs - between trend and torture

Next to their monochrome congeners, they immediately catch the eye: the brightly spotted merle dogs.

The wildly spotted coat gives the animals an extravagant appearance and appeals through its differentness.

But what is it about this special coat pattern and why is it so criticized?

What is the merle gene?

Merle dogs suffer from a mutation of the silver locus gene, which is located on chromosome CFA10. The blotchy special color comes from the fact that the merle gene lightens the pigment eumelanin. Animals with the base color black appear then gray in places (blue merle) and dogs with the base color brown get a reddish pattern (red merle).

shutterstock.com / Eudyptula

In some cases, the depigmentation also affects the skin and eyes, for example, trait carriers may have eyes of different colors (odd-eye) or combine several colors in one eye (iris heterochromia).

Although the appearance of the dog in most cases gives information about whether the dog is a trait carrier or not, there are variants in which the optical assignment is difficult (phantom merle) or not even possible (cryptic merle).

Pied fashion dog

Merle is very trendy at the moment. Some simply find the pied coat beautiful, others fall in love with the blue eyes or use their dog as an expression of status and prestige.

The fact that Merle has a genetic defect quickly fades into the background. Shady breeders see an opportunity to make big money and knowingly violate animal welfare laws and ethical standards.

shutterstock.com / Ivanova N

The merle factor and its health consequences

The German animal protection law forbids the mating of two trait carriers, because the merle gene can cause various health problems:

  • Diseases of the eyes,
  • damage to hearing,
  • abnormalities in organs and bone structure,
  • reduced fertility rate,
  • lethargy,
  • low life expectancy.


These health problems occur more frequently in homozygous (purebred/MM) dogs than in heterozygous (mixedbred/Mm) dogs, i.e.: not every Merle dog is necessarily ill!

Consequences for the buyer

Many buyers associate the merle factor mainly with visual characteristics. They are not aware of the fact that this can also be associated with increased demands on the keeping conditions or cost-intensive medication.

Additionally, behavioral problems can occur if the dogs are limited in their sensory perception. The standard rules in dog training are then often not effective, but must instead be laboriously and individually adapted to the competencies of the dog.

Preventive protective measures

In order not to further support the torture breeding of dogs or to prevent the accidental mating of trait carriers, you can observe the following points:

  • Only buy merle dogs with a pedigree.
  • Clarify with a gene test at the vet, whether a merle variant is present.

Typical dog breeds with merle factor

Dog breeds that are recognized by the FCI (Fédération Cynologique Internationale = largest cynological umbrella organization):

  • Australian Shepherds (Blue Merle/Red Merle)
  • Border Collie (Blue Merle/Red Merle)
  • Dachshund (Blue and Red Merle)
  • Short Harrcollie (Blue Merle)
  • Miniature American Shepherd (Blue Merle/Red Merle)
  • Mudi (Blue Merle)
  • Longhaired Scottish Sheepdog (Blue Merle)
  • Norwegian Hound (Blue Merle)
  • Shetland Sheepdog (Blue Merle)
  • Welsh Corgi Cardigan (Blue Merle)

In general, the merle factor can be crossed into any dog breed.

shutterstock.com / otsphoto
Banner: shutterstock.com / xkunclova
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