The Australian Shepherd, often called an “Aussie,” is a popular herding dog breed with a beautiful multi-colored coat. The red tri color pattern, with red, white and copper markings, is one of the most common coat colors seen in Aussies. However, there is sometimes confusion around whether a red tri Aussie is also a merle dog.
The merle gene causes a marbling effect on a dog’s coat and is responsible for producing some of the signature Aussie coat patterns. But the specifics of how merle works and interacts with other coat color genes can be confusing. So, are red tri Aussie’s also merles? Or does the red tri color pattern preclude a dog from having the merle gene? Let’s take a closer look.
The Genetics of Coat Color in Aussies
There are several different genes that interact to create the variation of coat colors and patterns seen in Australian Shepherds:
- The B locus determines whether a dog is black/brown (dominant B) or red (recessive b). This gives us the basic pigment options.
- The E locus codes for the black pigment. The dominant E produces black pigment, while the recessive e allows red pigment to show through.
- The A locus controls how much white/tan markings appear. The recessive a allows for minimal white markings.
- The M locus produces the merle pattern when the dominant M allele is present. The merle causes a marbling effect.
- The S locus determines how much white covers the body. The recessive sp allele produces large white areas and can create extensive white spotting.
Now let’s look specifically at how the red tri color is produced.
What Makes a Red Tri Aussie?
For a dog to have the red tri coat pattern, it must have the following genotype:
- B locus: bb – Homozygous recessive, allowing the coat to be red instead of black.
- E locus: E? – At least one dominant E allele, enabling black pigment production.
- A locus: aa or Aa – Homozygous or heterozygous recessive, limiting white/tan markings.
- M locus: MM or Mm – No merle alleles present.
- S locus: ss, Ss, or SS – No excessive white spotting.
The locations of the red, black, and copper/tan on the coat are determined by the interplay of these genes. But the key point is that to be a red tri, the dog cannot have a dominant merle allele (MM or Mm).
So red tri Aussies are not merles. The red tri coloration is dependent on a bbee genotype, while the merle patterning requires the dominant MM or Mm alleles. It is not possible for a dog to be both a red tri and a merle.
Common Aussie Coat Patterns
Here is a table summarizing some of the most popular coat patterns seen in Australian Shepherds and whether they can be merle or not:
As the table shows, the red tri pattern is the only common Aussie coat color that cannot also be merle.
Why Merle Is Not Possible in Red Tris
So why exactly can’t a red tri Aussie be a merle? Here are two key reasons:
- The merle gene (M) causes a marbling effect by randomly diluting black pigment. But in a red tri, there is no black pigment present for the merle to act upon, only red. So the merling effect cannot be produced.
- The red tri color requires two copies of the recessive “no black” allele (bb) from the B locus. But in order to have merle, the dog must have at least one copy of the dominant B allele that enables black pigment production. So a red tri is unable to genetically carry merle.
For a red tri Aussie to also be a merle, it would have to simultaneously have a bb genotype (to be red tri) and a BB or Bb genotype (to enable merle). This is genetically impossible, so no dog can display both coat patterns.
Real World Examples
To help illustrate this further, here are some photos of red tri Australian Shepherds compared to merle coat patterns:
|Red tri Aussie: Only solid red, copper, and white markings. No marbled coat pattern.|
|Blue merle Aussie: Marbling effect clearly visible in the black areas.|
|Red merle Aussie: Marbling in red areas instead of black.|
As you can see, the red tris lack any kind of marbled coat pattern compared to the merles. This demonstrates how a red tri coat color excludes the possibility of also being a merle.
One final reason why red tris can’t be merles is related to health. Merle Aussies require special breeding practices to avoid serious health problems.
Breeding two merle patterned dogs together can result in a double merle (MM) puppy. Double merles often have severe vision and hearing impairments. So intentionally breeding two merles is considered unethical.
By breeding a merle dog only to a non-merle partner, these risks can be avoided. The red tri pattern provides an ideal merle-free mate to safely produce merle pups. Mixing the genetics allows both coat patterns to continue in the breed safely.
So in summary, the red tri coat color is invaluable for providing genetic diversity in Aussies and enabling responsible merle breeding programs. Breeders can feel confident red tri Aussies will never carry or pass on the merle gene.
While Australian Shepherds are best known for their distinctive merle coats, the red tri color pattern also has an important place in the breed. The red tri stands out for its vibrant copper, red, and white markings devoid of any merling.
Through an understanding of the underlying genetics, we can confirm red tris are unable to genetically carry or display the merle coat pattern. The coat color requirements conflict, making it impossible for a red tri Aussie to also be a merle. So while the red tri may seem similar to a red merle at first glance, the two are definitively different.
So for those who love the classic red tri look, you don’t have to worry about any surprise merle genes cropping up down the line. A red tri is a red tri through and through.