If you’ve spent time in “Labradoodle” communities online, you may have noticed debates about Merle genetics. Some claim Merle is “unnatural” in the Australian Labradoodle, while others celebrate the stunning patterns it can create.
WHAT IS THE MERLE GENE?
The Merle Gene is a genetic variation that affects the pigmentation of a dog’s coat.The Merle gene is actually a genetic mutation that attaches to DNA. Merle affects the colouring of the coat, often giving the coat a dappled or mottled look — and it can also change eye colour. Sometime dogs may even display two different eye colours (heterochromia). Heterochromia does not affect the function of the eyes in any way and can be quite a beautiful appearance.
Let’s unpack the controversy together. This post will explain the Merle gene, how it works, and why it sometimes appears in the Australian Labradoodle. We’ll also address common myths and provide tips for those considering adopting a puppy.
WHERE DID IT ALL BEGIN?
Can you believe that the Genetic Merle Patterning originated in a single dog many hundreds of years ago. That’s right! The merle mutation really has happened only once in the history of dogs and all Merle dogs living today are descendants from that one mutant individual.
Traditionally, Merle was not associated with the parent breeds for the Australian Labradoodle which has fueled the belief that it’s “unnatural.” to be found in the Oodles Mixes.
In reference to the Australian Labradoodle, the infusion of the Merle Gene, happened many years ago and multiple ancestors prior to Genetic Testing for Merle becoming available. DNA testing of the “Breed Lineage” for individual dogs is available through Embark Genetic Testing. As far back as the DNA will allow, our Merle dogs have only shown, poodle; Labrador and Cocker Spaniel ancestry.
It is certain that Merle happened in Europe, likely in central or western Europe, and during a time when dogs were already more than "just dogs", when they had specific work to do. It may have happened a few hundred years ago, perhaps 250-500 years, either in herding dogs or in hounds. Not in a certain breed, as it has happened before there were what we now think of as "pure bredsI
GENETICS AND INHERITANCE OF MERLE.
Merle is a dominant gene, meaning a dog only needs one copy for the pattern to appear. However, when two Merle dogs are bred together, the pairing increases the risk of producing a “Double Merle,” which can be linked to vision or hearing loss.
Let’s get a bit technical. If you are not the nerdy type then feel free to skim over this section. The Merle Gene is inherited as a Sine Length. This can be imagined as a microscopic tail. The length of the tail will determine the characteristics of the patterning and the amount of dilution in the coat. There are seven alleles on the M locus. These are expressed as base pairs.
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m Non-Merle - Wild Type
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Mc Cryptic Merle 200 - 230 bp
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Mc+ Cryptic Merle + 231 - 246 bp
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Ma Atypical Merle 247 - 254 bp
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Ma+ Atypical Merle + 255 - 264 bp
- M Merle 265 - 268 bp
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Mh Harlequin Merle 269 - 280 bp
Here is what is important to take away from this scale. Shorter lengths of Merle may not be displayed on a dog’s coat. In fact Cryptic Merle can be regarded in a similar way to Non Merle. [m]. In addition, the Merle Gene does not show up in Cream, Caramel and Red Coats so you cannot assume that a dog does not carry Merle just because he or she does not look Merle. Testing is essential!
Merle is a dominant gene, meaning a dog only needs one copy for the pattern to appear. However, when two Merle dogs are bred together, the pairing increases the risk of producing a “double Merle,” which can be linked to vision or hearing loss. With careful, responsible breeding, Merle patterns can be expressed safely, while avoiding the health risks linked to double Merle dogs.
THE IMPORTANCE OF CHOOSING THE RIGHT BREEDER.
When considering a Merle puppy it is important to do your homework. Have both the dam and the stud received genetic testing? Have the Merle Lengths been measured? Where is the Merle inheritance originating? Some breeders have sourced the Merle from Border Collie Lines which is not an approved foundation breed for the Australian Labradoodle. At other times, the Merle may be obtained directly from back-crossing to a poodle, resulting in more wool coats in the offspring.
THE MAGIC OF MERLE.
Merle is so much fun. I love the uniqueness of patterning and the surprise element. No two Merle puppies are ever the same. Because the Merle gene carries both beauty and complexity, working with a responsible breeder is key.
At Burrinjuck Labradoodles, we prioritise the health of our dogs in every decision we make. All our dogs are health tested and their Merle Length is scored to ensure health, vigour and beautiful patterning without compromise. Families can feel confident when welcoming a Merle puppy into their home.
These litters have been meticulously planned to ensure we can breed incredible and stunning puppies from premium bloodlines that tick all the boxes for your perfect fur-ever new addition. 
