There are lots of dogs with different fur patterns, colors and spots. do these patterns and colors say anything about our beloved furry friends? well yes! ha! you didnt know right ?
There are some breeds of dogs known to have patterns on their coat/fur that is suggestive of a “condition” known as merle. the dogs could have a dominant or recessive gene/dna of the merle.
Most dogs with two merle genetic codes are deaf in both ears. This shows how complex the genetics of the merle hair pattern are.
The dapple in some breeds makes the dogs look unique with their mottled or dappled look. It’s found in many dog breeds, from the eye-catching blue merle to the deep red merle.
The dapple gene is an old mutation that came before modern dog breeds. It shows a common genetic link among dogs.
This gene, marked by the letter M, creates the merle design. It shows up as patches of color on a lighter background.
When a dog gets one merle dna, it looks spotted. But if it gets two, the effects can be serious.
What makes a Merle Coat Pattern?
The merle coat pattern is a unique look found in some dog breeds. It’s caused by a specific genetic material that lightens parts of the coat to grey.
This gives the dog a mottled appearance, with patches of their original color next to lighter areas.
Introducing the Merle Gene
The merle allele, marked by the letter “M,” causes the merle pattern. It changes the pigment eumelanin, affecting black, liver, blue, or isabella colors in the coat, eyes, and nose. the “M” representing the dominant merle gene.
The non-merle allele, shown as “m,” also plays a role in the merle pattern’s look.
Breeds with Merle Coat Patterns
Some dog breeds have the merle allele, like the Australian Shepherd and Catahoula Leopard Dog. Others include the Norwegian Dunker and Border Collie.
The list also includes the Hungarian Mudi, Cardigan Welsh Corgi, and Collie. The Shetland Sheepdog, Dachshund, Beauceron, Bergamasco, Pyrenean Shepherd, and Great Dane also have this pattern.
Recently, the spotted pattern has been added to breeds like the Chihuahua, American Staffordshire Terrier, American Cocker Spaniel, and Pomeranian.
The Genetics Behind the Merle Pattern
To grasp the genetics of the dapple in dogs in some breeds, we must look at the merle allele (M) and its inheritance. This gene is dominant, so just one copy is needed to show the merle look.
Dogs with the Mm genotype will have the striking merle pattern. Those with the mm genotype won’t. The merle look comes from a SINE insertion in the SILV (PMEL17) gene. This affects how melanin pigment is made.
The Merle Allele and Inheritance
Studies show that the dapple pattern comes from a SINE insertion in the SILV genetic code. The length of the SINE can vary among dogs and even within the same dog, leading to different dapple patterns.
Changes in SINE length often result in more pigment in the coat, affecting the dog’s color. There are also cases where the SINE length increases, showing just how varied these lengths can be.
Knowing about the merle allele and its inheritance is key for breeders and dog lovers. It helps identify the merle genotype and avoid health issues linked to the merle color. This is especially true for breeds where the merle can be hidden by various coat colors.
Variations in Merle Coat Patterns
The merle fur pattern in dogs can look very different. Some have just a few black patches, while others have big patches all over.
The base color can be light, like a “powder blue,” or dark grey with a special pattern, known as a muddy or ticked merle. It’s important to know that “blue merle” isn’t the right term for these dogs. They should be called “black merles.”
Patching and Base Color Variations
The look of merle patterns and base colors changes a lot because of the SILV genetic code. This genetic code affects how melanin is made during growth. Here are some important things to know about merle coat variations:
- Dogs with the shortest lengths of the oligo(dT) region in the SILV gene might not have the merle coat pattern. This is called cryptic merle.
- Standard merle dogs usually have oligo(dT) lengths between 78 and 86 base pairs. Dilute merles have shorter lengths, and harlequin merles have the longest.
- Coat dilution in merle dogs starts with oligo(dT) lengths between 56 and 66 base pairs. Patches of full pigmentation start to show up with lengths between 75 and 78 base pairs.
- Longer oligo(dT) lengths often lead to more varied coat patterns, like tweed.
These genetic factors lead to the wide range of merle fur variations, merle patching, and merle base color patterns seen in dogs. This includes everything from blue merle to ticked merle and muddy merle looks.
Eyes and Nose Pigmentation in Merle Dogs
The merle genetic information creates a unique coat pattern in some dog breeds. It also affects the pigmentation of their eyes and noses. This leads to a visually striking look for merle dogs.
Merle dogs might have all or part of their eyes appear blue. This happens because the merle genetic information changes how melanin is made. It can cause the iris to lack pigment partially or fully. Also, they might have a “butterfly” nose, which is mostly pink.
Not every merle dog will have blue eyes or a pink nose. The amount of pigmentation change depends on the breed and the dog’s genetic code. Dogs with darker patches on their coats are more likely to have normal eye and nose colors.
The merle gene affects melanin production all over the body. This genetic variation leads to a wide range of unique and striking features. It makes merle-patterned dogs even more appealing.
what makes a dog a merle
The dapple pattern in dogs comes from a special genetic mutation in the SILV (also known as PMEL17) dna. This gene helps create a matrix that keeps pigment in place, giving dogs solid coat colors. But, if the SILV dna has extra genetic material, it messes up this matrix. This lets pigment granules spread out, making the merle coat look mottled and patchy.
The size of this genetic insertion in the SILV gene changes as cells divide during growth. This can make the merle patches vary in size and position on a dog’s body. This is why merle patterns can look different in various breeds and even within the same breed.
Merle Modifiers and Dilute Spots
Other dna can also change how the dapple pattern looks. For example, a gene that dilutes spots can make the merling less intense, creating a softer look. These genes work with the SILV dna to make merle coats even more unique and eye-catching.
Learning how the SILV gene and other genes work together helps us understand the many fur coat patterns in dogs. By studying merle genetics, breeders and fans can guess and manage the look and health of this special coat pattern.
Hidden and Cryptic Merle
The spotted pattern is unique and popular in some dog breeds. It’s important to know about hidden and cryptic merle for responsible dog breeding and care.
The merle dna can be hidden by the recessive red allele (ee) at the E locus. Dogs with this allele lack eumelanin pigment, showing a solid red coat. These dogs, though not visibly merled, can still carry the merle dna and pass it on to their offspring.
Cryptic (phantom) merles have very slight merle coloration. They can look like non-merle dogs because their merle markings are hard to see. It’s important to check puppies closely to spot these hidden merles. Breeding these dogs can lead to health issues in their puppies.
In summary, hidden and cryptic merle are key concepts for merle dog owners and breeders. Being aware of these variations helps ensure the health and happiness of these dogs.
A genetic test at Texas A&M Vet School helps breeders know if a dog has 1, 2, or zero merle genes, it is possible to get to get your dog assesed at a vertinary to know if its part of the merle dog breeds. This test helps breeders make informed decisions. By understanding hidden and cryptic merle, we can promote responsible breeding and protect the health of merle dogs.
Health Concerns with Merle Coats
The merle fur pattern is eye-catching, but it comes with health risks. Dogs with this pattern often face deafness and blindness. These issues are more common in double merle dogs.
Double Merles and Breeding Considerations
Double merles have two copies of the merle gene, making them mostly white with small patches. Breeding two merle dogs together is risky. It can lead to double merle puppies, which face serious health problems.
- Responsible mating between a solid-colored dog and a merle dog result in offspring that are 50% merle and 50% solid.
- Irresponsible breedings where two merle dogs are paired produce offspring with a breakdown of 1/4 solid dogs, 1/2 merle dogs, and 1/4 double merle dogs.
- homozygous merle dogs can experience a range of health issues, including hearing impairment, vision impairment, microphthalmia, and skin cancer.
- Some dogs with homozygous merle dna are stillborn or do not survive the first weeks of life, while others may reach adulthood but suffer from health challenges.
- Merle dogs with only one copy of the gene can be as healthy, strong, and smart as solid-colored dogs.
Breeders must be careful with the merle coat pattern. They should think about the health risks. By being responsible and using genetic tests, breeders can avoid double merles and their health issues.
Conclusion
The merle fur pattern in dogs is both fascinating and complex. It is controlled by the SILV gene and the merle allele. This pattern can create unique and beautiful coat colors. However, it’s crucial for breeders and owners to know the health risks and breeding standards associated with double merle in dogs.
Responsible breeding and genetic testing can help celebrate the merle trait while focusing on the dogs’ health. By choosing the right breeding partners and avoiding two merle-coated dogs, breeders can prevent double merle puppies. These puppies often face severe vision and hearing issues.
Research and education are key in the dog breeding world. Understanding the science behind the merle pattern helps breeders make better choices. This way, we can ensure these beautiful dogs live happy lives without health problems.
