Information About The Merle Gene
Merle is not a color in and of itself; it is a splashed color pattern with many variations. It is a very interesting color pattern and merle Pomeranians are very sought after in the US. Despite its popularity here, this is not an overly common coloring for this breed because of the very careful breeding that is required to produce a healthy litter.
The merle gene is a dominate gene that weakens the primary color of the dog. This gene will often alter the dog’s eye color in part or whole (mixes it with blue). The dog’s skin, pads, lips, nose, eye lids, etc., may also be spotted, reflecting the dilution of color. Many gorgeous examples of merles are now seen in the Pomeranian breed! This is an exciting new color pattern that is here to stay!
MM – a double dominant merle - This dog has two merle parents - This dog received a merle gene from each parent ***Do NOT breed a merle dog to another merle. While a merle dog from a merle and non-merle parent is healthy (Mm), merles bred to merles (MM) can throw significant health issues such as eye defects including blindness, eye deformity, deafness, skeletal issues, and weakened sperm production. This mostly occurs in the white offspring resulting from a merle to merle breeding (approximately 25% of the time).
Mm – a merle dog - has only one merle parent.
mm – a dog without the merle gene present although it may (or may not) have a merle parent.
A merle dog MUST have a merle parent.
However, it is imperative for one to be careful when wanting to breed a merle dog. The safest breedings are with the darker colored dogs because it shows the merle characteristics much more readily than a lighter colored dog.
Merles crossed with blacks produce blue merles (a distinctive diluted black). When crossed with chocolate, a chocolate merle can be born, and when crossed with red, produces red merles. However, one cannot be sure whether a light colored dog carries the merle gene (light orange, cream, white, sables, brindles, etc.).
**Do not breed a merle dog with an ee/recessive red.
A dog that is homozygous for recessive red, so has the genotype ee, will be completely red. Its nose will remain black, (or whatever its eumelanin pigment color is), and so will its eye rims and lips, but the rest of its coat will be solid red (with or without white markings). This is because the recessive red gene, in effect, gives the skin cells a disability (but not a harmful one!) - it stops them from being able to produce eumelanin (The K locus determines whether a dog is solid-colored (eumelanin only) or has red/tan (phaeomelanin) in its coat as well. There are three genes in the K series, and if a dog has one or two K genes (K is the top dominant in the series, so it overrides everything else), it will be solid-colored).
It is therefore impossible for a recessive red dog to have any black or blue in its coat. Recessive red, although recessive in its own series, is essentially dominant over almost all other. Dominant black, sable, tan points, wolf grey, merle, and any other pattern with black in it will be turned to solid red by the recessive red gene. This, in a way, is the danger of recessive red - it can mask so much.
It's impossible to know from looking at a recessive red dog whether it carries sable, tan points, brindle, or any other A or K locus gene, and so impossible to know what it will pass down to its puppies unless you know its family history.
A recessive red dog could even be merle while still appearing solid red, and this is a problem that has arisen in Pomeranians, among other breeds. Merle is a recent addition to the Pomeranian breed, and it is entirely possible for double merles (MM) to be bred by accident because recessive red is so common in the Pomeranian breed.
The only way to tell if a recessive red dog is merle is if it has blue or partially blue eyes (which not all merles do), so it would be easy to accidentally breed two merles (MM) together if you weren't aware of how the merle gene can be hidden. The best way and only sure way to prevent this is genetic testing to insure your red pomeranian isnt an ee/recessive red pomeranian.
If a merle dog has a litter with sable or light colored puppies, it is very difficult to tell whether the puppy is a non merle dog or a "Phantom merle". The only way to tell could possibly be a slight spot of blue in one eye. The only tell tale signs that the dog is a phantom merle are their colored eye/eyes and mottled nose/skin. Why is this important to know? If a breeder unknowingly bred the “phantom merle” to a merle, there is a strong chance that 25% of the puppies would be double dominant (MM) and have serious health defects such as eye, vision, or hearing issues.
It is easiest to tell at birth whether the dog is a merle or not – (unless a phantom merle has been produced).
When breeding for merles, the best colors to use for the non-merle parent are blacks, blues, chocolates, or black/blue/chocolates with tan points. It is said that nearly 50% of the offspring will be merle when using this breeding regiment.
In our my experience, however, it has been about half to a third of the offspring. When in question on whether a phantom merle has been produced, it is best to test the dog's genetics, neuter the dog, or alert the owner that the dog may be a merle and not to breed it to another merle (so that the health of future puppies is not compromised).
A dog that is not a merle (or phantom merle) but has a merle parent cannot pass the merle gene onto his/her offspring. This dog can also be bred back to a merle. Only then could it produce a merle in his/her litter.
There is a lot of confusion about a merle parti dog that is mostly white, extreme piebald parti merle that is mostly white, (or even a phantom white merle). You can breed merle partis & phantom white merles as long as they are bred with a Non-Merle. They may LOOK like a double dominant merle-to-merle (MM) breeding, but they are not! The only Pomeranians that are serious health risks for this is when a merle has been bred to another merle (MM) (including phantoms).
We DO NOT recommend breeding any merle to a cream or solid white (not a parti) - you may not know you have a merle and therefore, this could cause future problems (MM problems) - especially if the dog is sold to someone who knows nothing about the merle issues.
We have also heard of issues with other breeders when breeding an ice white to merles - same type of issues as breeding merle to merle (MM). Please stick to breeding merles with darker colored dogs (Blacks, Blues, & Chocolates) although you will get some light colored dogs, they won't have the health issues.
**A merle gene is actually a heterozygote of an incomplete dominance gene.