Merle Chihuahuas
The debate on merles has be raging for a long time now. One one side, breeders are claiming that the merle has resulted from the cross breeding of chihuahua's to another breed, while others have claimed that they have seen it for many years.***Please see note at the bottom of the page***
In our opinion, this is one of the most beautiful color patterns seen in the chihuahua today, please see Kasey.
Recently, the Chihuahua Club of America published this article on the merle chihuahua.
The Merle Color Pattern and Chihuahuas In short that have decided to leave the standard as is and accept the color pattern.
Finding the Right Merle Chihuahua
Everyone wants the perfect puppy, and the merles are no different. With this color pattern, no two will ever look identical. However, alot of responsibility falls on the breeder and buyer with this coat. If you decide that this is the coat color for you, try to visit the breeder personally and see both of the parents. ONLY ONE parent should be a merle. If both parents are merles, RUN!!! You can end up with severe problems with your pup. Also, the parents should not be a merle and a brindle (this will not cause problems, but sometimes merle patterns can look brindle and brindle patterns can look merle which can make correct identification hard). Try to avoid the merle pups that are mostly white, as most Double Merles are mostly white, and Double Merles have alot of health problems, see the genetics section below. If you do find one that you love that is mostly white, again, ask to see both parents, as one of them could have been a spotted (look at the ears of the pup, most double merles will have white ears). If one parent is a fawn, ask if there is any chance that the fawn is a cryptic merle (also known as phantom merles). The breeder should be able to show photo documentation to support the coloration. If you go to a breeders house and they try to sell you a cryptic merle, be sure that they show you photo documentation of the merle pattern from when the pup was younger. If they do not have this, proceed with caution. Most reputable breeders take at least one photo a week of their new babies as they are thier pride and joy.
Breeding Your Merle Chihuahua
Merle Chihuahuas are some of the most beatiful chis out there today, and as a result, many people are now breeding for this color to supply the demand.
If you are thinking about breeding merles, you need know that the merling pattern is a dominat gene, this means that one parent MUST be merle for the pups to merle(There is what are known as a phantom merles, meaning that the puppy was a merle, but the spots faded, but this only happens in fawn pups.) So don't buy a puppy from a breeder that tells you that because the mother or father was a merle, that the puppy is carrying the merling gene and can have merle puppies. Dogs carry recessive genes, like a black dog that can have chocolate pups. Merling is a dominate gene, therefore it must be seen in the dog for the pups to have it.
Okay, so you got a merle and are ready to breed. NEVER NEVER NEVER breed two merles together!!! THIS IS VERY DANGEROUS! The genetic mutations that result from this can range from blindess to pups being born with no eyes, hearing problems and the double merle pups are almost always sterile. Being a merle breeder, it is best if you can breed your merle to darker colors, such as black, blues, chocolates or lilacs. This keeps the colors very viberant, and reduces the chances of having phantom merles.
Also, unless you are a very experienced breeder, do not breed a merle to a brindle, as this can sometimes make the markings hard to tell if the offspring is a merle or a brindle.
If you decide to breed merles, check the pups at birth for the spots, and take pics to document them, this way you can be sure to mark them correctly on their paperwork.
So would it be safe to breed a blue merle dog to a blue dog? You can safely breed a blue merle to a blue as long as the nose leather of the merle dog is BLACK!! If the nose leather is blue you really have a dilute blue merle and you could risk the skin problems as if you bred a blue to a blue.
Merle Genetics
The merle gene is a dilution gene, meaning that it lightens the color that would otherwise be expressed in the coat.
The merle gene itself is an epistatic gene. This means that it has effects on other color genes, not only it's own genetic partner. This being said, it its also worth noting that contrary to popular belief there is not a blue merle gene or a red merle gene, simply the merle gene that affects color. Another odd thing about the merle gene is that it is incompletely dominant. Incomplete dominant genes do not act the way a complete dominant gene does. For example, if a dog is B/b genetically, the dominant Black (B) completely covers the recessive Chocolate (b). When a dog has the copy of Merle (M) is only dilutes the coat color in patches, creating the random spotting or streaking that is seen. If merle was a completely dominate gene it would dilute all the color patches.
The merle gene is also considered to be caused by a transposable element. These are segments of genetic material, or DNA, that can change its location, or remove itself from that gene. This is what is responsible for the color varation. The coat pattern is determined during embryonic development and the cells that the gene removes itself from will be the darker patches of the dog. The cells that the gene remains in will be diluted. The acts of this gene are totally random, and as a result no two merles will never be exaclty alike.
This is a puppy from our Tequila X Kasey. Notice the bi-color marking on both the front and back legs, this is called a tweed merle.
Problems Associated with the Merle and Double Merle
Most of the vision and hearing problems are associated with the double merles, however, there have been some "normal" merles that have vision and hearing problems.
Double merles have also been referred to as white merles, excessive whites or lethal whites. The correct genetic term for them is homozygous merles.
Below is a list of the problems that have been associated with the merling pattern. Most of the time it only affects the double merles. It is very rare for a dog to have both a hearing and vision problem. It is also worth noting that none of these are exclusive to the merle pattern.
Vision Problems
Anophthalmia: Complete absence of the eye.
Corectopia: This is a subluxated pupil, or when the pupil is not center in the iris. Sometimes referred to as a dropped pupil. Depending on the severity of the abnormality, the dog my be able to cope.
Eccentric Pupil: When the dog's pupil is misshapen, having jagged or irregular edges.
Microphthalmia: This is an abnormal smallness of the eye, and is also the most common vision defect that is seen in double merles. The severity of this can range from very mild to almost no eye visible. The smaller the eye, the more vision trouble the dog has.
Starburst Pupil: When the dog's pupil is misshappen, having spikey projections that resemble a starburst or sunburst pattern.
Their are also vision problems in the inner eye that cannot be seen by the naked eye. It is always a good idea to have your double merles checked by a veterinary ophthalmologist. Hearing should be checked by a veterinarian.
Also Little's work has noted that these doubles merles have infertility problems.
Fragile Merle Gene?
It has been theorized that the merle (M) gene is a fragile gene and has a high probability of mutation back to non-merle (m). This is because there have been litters in which a double merle (MM) was bred back to a non-merle (mm) and black were produced. If we look at the genetic square, you can see that 100% of the pups should be merle.
There are two possibilities here. First, the gene has mutated back to a non-merle state, or second that the dog is actually a cryptic merle that that has no markings because the ramdom patching covers the entire dog. Granted this would be rare, but so would the possibility that merle is a fragile gene. To know this for sure, the breeder would first have to breed a double merle (not recommended), then the double merle would have to be bred back to a dark colored non-merle dog until a solid pup was produced, then that solid pup would have to be bred to another dark colored non-merle dog. If this was a crytpic merle, 50% of the pups from this mating should be merle, while the other 50% should be non-merles. If even one merle is produced, it proves that the dog was a cryptic merle.
**NOTE**
Recently I came across a book called Know your Chihuahua by Earl Schneider
that was published by Pet Library, New York, in what appears to be the late sixties. I found this date on one website. [1967?]. The red box shows where this author mentions the merling pattern in the chihuahua for going on 40 years.
There are merle color examples on my Merle vs. Spots vs. Ticked page.