Merle Cocker Spaniels: The Good, Bad and the Ugly.

August 3, 2022

Merle-coated dogs range from Irish Red or Blue Great Danes, Australian Shepherds, Shetland Sheepdog, Airedale Terriers, the Cardigan Welsh Corgi, and Cocker Spaniels.

Despite their visual similarity, each breed has its own unique set of genetic markers, so it’s important to understand the differences before bringing home an adorable Merle Cocker Spaniel.

Even though they’re among the most popular of all spaniels, most people don’t know much about Merle Cocker Spaniels – from origin to disposition – let’s take a look!

What is a Merle Cocker Spaniel?

The term “Merle” is used to describe a coat pattern of any colour but is most often used to describe black, brown, and blue-gray dogs with a flecked, splotchy or spotted pattern.

Most Merle Cockers have solid black patches on their ears, tail, and legs, while their heads, bodies, and bellies are interspersed with dark brown spots. When the black sections of the coat are interspersed with rust-coloured spots, it’s called “Blue Merle.” Solid blue-gray Merles are known as “Black Merle”.

It's also common for a merle dog to have one brown eye and one blue eye, or even two blue eyes. This beautiful feature makes them attractive to a dog lover, but buyers beware. We're going to cover the pros and cons of merle pattern dogs.

Merle Cocker Spaniels: Origins and Meaning

Their origin remains unknown, but most experts agree that it’s an ancient breed. It’s also generally accepted that Merles are inbred with the American Cocker Spaniel, the English Cocker Spaniel, and the Field Cocker Spaniel. One hypothesis is that the merle gene was introduced through an outside breed, though it is not possible to prove this scientifically.

Although no official documentation exists, it’s believed that Merles were bred to assist hunters. Most ancient dog breeds (such as the Cocker Spaniel) were bred to be versatile: they hunted, herded livestock, and were guardians of the home. Merles were likely bred to be a jack-of-all-trades, but they were most often used as hunting dogs.

Merle Cocker Spaniels: Breeding and Genetics

Breeding Merles presents an ethical dilemma. While they’re beautiful dogs, breeding two Merles together will always result in a litter of all Merles or all Black Merles. This is called double Merle. This means that every single puppy in a Merle offspring litter will be born with a severe and life-threatening genetic defect called “Merle” Encephalopathy (ME).

When this occurs in humans, it’s called “leukodystrophy,” and it’s uniformly fatal. ME is a degenerative seizure disorder, often accompanied by blindness, seizures, and other neurological problems. When breeding Merles, most owners will breed merles with a non-Merle, hoping that the gene for ME will be diluted enough to prevent it from manifesting in the puppies.

This is standard practice in all Merle breeds, and while it prevents ME from occurring, it also results in less-than-ideal Blue Merle or Black Merle puppies. It is not advised for responsible cocker breeders to breed merle cockers. In fact, double merles are a phenomenon that should be avoided in all breeds as this same genetic mutation will occur.

Why Are Merle Spaniels So Rare?

The Merle is a rare breed because of its Merle gene. The Merle gene for ME, unfortunately, is dominant, which means that all puppies in a litter will be Merle. To maintain the breed’s numbers and avoid potential health problems, the majority of Merle Cocker Spaniels are bred with non-Merle Cocker Spaniels.

Per the American Spaniel Club, Merle is not a standard Cocker Spaniel colour and is not considered a purebred cocker spaniel. The standard colours are: 

  • Black Varieties: Solid colour black including black with tan points, any solid colour other than black, ranging from lightest cream to darkest red, including brown and brown with tan point
  • Parti-colour variety: Two or more solid colours that are well-broken, one of which must be white; black and white, red and white (red ranging from light cream to dark red), brown and white, and roans, to include any such colour combination with tan points.
  • Tan Points: From the lightest cream to the darkest red and is restricted to ten percent (10%) or less of the colour of the animal.

 The American Kennel Club-Canine Health Foundation categorizes merle as a disease for which there is genetic testing. As a result, the AKC-CHF concludes that merle is detrimental to the breeds.

The good and the bad of owning a Merle Cocker Spaniel

The good: Spaniels are loving dogs who make excellent family pets. They’re playful, energetic dogs who love to be active, and they’re excellent swimmers. Their long, silky fur requires regular grooming, but it also sheds very little.

They’re empathetic, endlessly affectionate, and great with children who are old enough to treat them with care. They’re playful dogs who enjoy both swimming and walking. Their webbed paws make them excellent swimmers, and their enthusiasm for water makes them ideal dogs for hunting and fishing with their owners.

On the other hand, a dog with a Merle genetic mutation can often suffer from neurological problems that prevent them from enjoying life to this extent.

The bad: Merle dogs are rare, and breeding them can result produce significant health issues. Blue Merles are stunning dogs, but they’re the result of breeding two Merles together, which can cause devastating neurological defects in the puppies.

Neurological defects can lead to behavioural issues like anxiety, or worse, aggression.

Breeding dogs with the merle gene can produce offspring with numerous health issues including hearing loss and ear abnormalities, a variety of eye problems and blindness, colour thinning, hair loss/baldness, seizures, and other problems, including death.

As stated before, this merle phenotype is considered a disease according to the American Spaniel Club and American Kennel Club-Canine Health Foundation.

Responsible merle breeders will always follow the breed standard, have a certificate of health for your merle puppy and perform DNA testing. If you're purchasing from a breeder, it's important that you insist on only buying from someone who is follow responsible breeding techniques. Otherwise, the general puppy buying population is contributing to this problem.


The Merle Cocker Spaniel is a sweet and beautiful breed, but breeding two dogs with the merle colour together can result in devastating neurological defects in the puppies.

If you’re considering bringing one into your life, make sure you understand the risks, and if you’re a Cocker Spaniel owner, be careful not to judge your breed by the faults of another.

Allan  Noble
Hi, my name is Allan! I am the owner of Spaniel Advisor and I've got over seven years experience of owning Spaniels.  
I hope this article was helpful for you! 
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