Colors, Markings, Patterns, and Genes that cause them
This page is dedicated to helping those interested in colors, markings, Patterns and genes at play that cause different patterns, what are they, and what they mean to you and your Chihuahua. We will make all attempts to stay current with research.

*** It is also meant to educate those interested in the Controversy over the Pattern Chihuahuas through scientific fact, NOT ONE SIDED EDUCATION, TRUES about both PATTERN GENES THAT ARE FOUND IN THE CHIHUAHUA and all merle breeds, that's right there are TWO PATTERN GENES IN THE CHIHUAHUA, both carry the same HEALTH RISKS*** 

~Both pattern genes carry the same associated health concerns, and some independent concerns to each pattern. We believe both patterns can be bred healthy when you know what to look for, test for, and screen for. We have developed our breeding approach in order to breed RIGHT. We want everyone to have theirs~ 

**This pattern page is our understanding of research that has been completed by end of 2008(reading new research in 2011/links updated) and our interpretations of that research: we provide links to some references, we encourage you to research for your own understanding, and to keep going back as medical advances are made daily** 
Colors And Markings
the first issue we will discuss are colors and markings, this is the easiest to address
Registration Listed Colors For AKC in 08':
Black
Black&Tan
Blue&Tan
Chocolate
Chocolate & Tan
Cream
Fawn
Fawn &White
Red
Markings
Black Mask
White Markings
Merle Markings
Spotted on White
Black Sabling
Black Brindling

***Chihuahuas can also be TICKED, ticked Chihuahuas can be confused for merle Chihuahuas. A clue a dog is ticked and not merle, is ticked affects white areas or patterns, merle does not will NOT affect white, if you see ticked areas in white markings or patterns, your Chihuahua may be carrying the ticking gene. It is considered by most researchers to be a dominant gene, therefore it can be invasive to your breeding program***

***Chihuahuas also carry a dilution gene which confuses many people, a chocolate dilute for example will be the color of a cream with a chocolate or self pigmented nose, these Chihuahuas are most often registered the color they closest resemble, BUT it is IMPORTANT you know that your Chihuahua is carrying the DILUTION GENE as it, too, is a pigment reducing gene, and it should be bred properly. We do not recommend breeding certain colors to the dilution carrying Chihuahuas. Please study dilution genes if you want to breed them.

~~~ there is an extended color list by AKC for Chihuahua breeders in order to better classify your Chihuahua~~~

Please keep in mind it does not cover all colors, like your blue creams, chocolate creams, tan on tans, for example. These are results of the Dilution gene, diluting you base color and removing pigment from your dog.


(also if you aren't sure what color your Chihuahua is you can always submit pictures to AKC, have them review the photos and they will choose the correct color. Better to do this, than to just guess)
Chihuahua Breed Standard

Any color - Solid, marked or splashed.
AKC Merle Chihuahuas

Remain a registered, breedable, Showable color pattern. Nothing has changed. They remain part of the standard in the U.S.A., Even though there has been a strong debate here as well in many other countries. 

Recently the issue was put to rest, for some years to follow. Some are please with this outcome, while some individuals are saddened by the outcome, our goal is to breed healthy, sound, typey, Chihuahuas for show and we happen to breed both patterns.

We respect both non-merle and Merle breeders.

EYE ISSUES
Spotting pattern gene and the merle pattern gene
*** this is a very complicated issue for many, although it is lengthy to discuss We will attempt to keep it as simple as possible. The merle Chihuahua issue and the spotted or white Chihuahua issues have not been well thought out and/or reported on, by many breeders in many breeds. We will attempt to inform those interested in scientific answers to pattern genes and the health risks associated with both types of patterns, and how to breed them safely.*** 












































































































So we addressed colors, eye colors, and the pattern issues, now we discuss the two last issues in Chihuahuas
Size
Purity

SIZE
Chihuahuas are supposed to be between 2-6pounds. Both NON-MERLE Lines and MERLE Lines can have offspring that are less than 2 pounds and even more often ones that are over 6 pounds. Quality breeders will be striving for Chihuahuas that are between 2-6 pounds, but that does not mean we don't get some too big or too small. 


NO CROSSBREEDS/PUREBRED ONLY
at Mahkota Chihuahuas we do not bred crossbreeds, and have no interest in crossbred Chihuahuas. We ONLY have interest in AKC purebred dogs.
LONG COATS
It is well known that Poms and Paps and possibly Peks were introduced years ago to increase the quality of the long coat variety.  Which also adds breed specific health issues from each breed added. Our concern is... is it still happening? Recent reports have shown that some long coat lines continue to not test pure. One such line was known to be a Champion from imported lines. If you're long coat gives you concern, this site can test for your dog's purity. For those of us interested in protecting our purebred lines this site has been very helpful, and is a wonderful way to ensure the integrity of the AKC PUREBRED DOG.

Does this mean that Long Coats are not pure?
NO!!! What is part of the past is the past. The point is with reputable lines they will test pure yesterday, today and in the future. This is why you want to find a reputable breeder, whether they are a non-merle breeder or a merle breeder. If you have a long coat that you question, the point is don't be afraid to have it DNA'ed for purity, if purity is something you strive for then DNA it.

Did you know that Poms and Peks have recorded cases of Albinism? Could this be were the recessive blue eye came from? I don't know but it is something to follow the research on.

Defining the form of Albino in Poms and Peks

Albino Locus related to Poms and Peks


MERLE CHIHUAHUAS
Sadly some very respected Chihuahuas breeders/exhibitors have a strong dislike for the merle pattern. This I can respect, as I have my favorites and ones I don't care for either. It is all about respect. And I do respect their dislikes. 

However, some breeders have chosen to proclaim a verdict before the research is completed. By following some anti-merle propaganda, suggestions and statements, they are openingly reporting Merle is a result of a crossbreed of recent introduction...This does not mean that they are deliberately being wrong, it is simply something they were told or read somewhere. What we know today.... is..... No medical research confirms such claims. And some researchers admit to possibility of spontaneous mutations, while all dogs carry the "m" gene and no research can prove how long the merle Chihuahua has been in existence at this time, added to the fact "Mm" (merle gene) dogs are Identical no matter which breed it is found in, Whether they are a Great Dane or a Chihuahua, there is no way to pinpoint a source like some would want to suggest certain breeds.  History books will clearly show photos of merle Chihuahuas in early 1900's. Researchers have not ruled out spontaneous development as some findings indicate that the merle allele was present in all dogs before the divergence of breeds, and when the bottle neck of geographic's occurs the genomes line up correctly for certain events and changes to take place. This could be why some disorders are evolving and why the merle Chihuahua came back into the picture. If you are interested in articles you can email us. So again the past is the past, we need to work towards the future.

Proudly we announce every merle Chihuahua tested, has come back PURE CHIHUAHUA from reputable AKC breeders with use of the Canine Heritage Breed Test. Does this mean every Merle Chihuahua out there will test pure?, sadly as is the case with some bad breeders, some will not. This is why you need to find your Chihuahua from a reputable breeder, no matter what color, coat length or pattern you are looking for.



Again, some lines continue to show they are only secondary Chihuahuas, and primary breed continues to remain unknown. 

**Again I respect breeders that don't like merle Chihuahuas. We all have a right to breed colors and patterns we enjoy and like. Our goal is to do it well, and for the integrity of the breed**

~If purity is a goal~Then test~We have~
THE TRUTH and DEFINITIONS: 

Researchers are still researching both genes, let them finish what they started.  The merle gene is still being studied, and so is the spotting gene. They are discovering the truths about the genes.
***2010 update on research for the PIGMENT PATHWAY***
Both pattern genes have health concerns to consider, they CAN carry microphthalmia, note in the prior link that both merle and white factored dogs are at risk to carry Microphthalmia it does not mean all will or do, and congenital deafness, congenital blindness, and some other disorders. You need to how to breed patterns to avoid health concerns, this is easy to do when you know what you are doing. Remember Quality breeders have been breeding merles and piebalds for many decades and generations safely in numerous different breeds, without causing harm to their breed of Choice.

TRUTH:
We are not seeing blind/deaf Chihuahuas with any noted percentages whether they are merle patterned or spotted patterned. I know of NO merle Chihuahuas that have not passed their cerf and baer tests. I have not had one solid or spotted carrying or actual spotted not pass their cerf and baer test. They all passed. Merle breeders have a current history of testing with higher percentages, then non merle breeders. Merle breeders tested to ensure to those concerned that the merle Chihuahuas were indeed not affected and remained healthy when bred in the heterozygous state(one copy of the merle gene). We also believe that all Chihuahuas should be tested for CERF, and BAER especially if white hairs extend into the ear canal. Although many Chihuahua breeders aren't testing... "We hope this changes". 

Spotting gene, is the white factor of the dog, for years researchers and genetically interested breeders used terms to describe the amount of white factor present on a dog, S(solid, or may have a white chest spot, toes spots, star or blaze on forehead) S1 and S2(the amount of Irish spotting), S3 (spotted on Whites or piebalds usually with 50%-75% white markings) and S4(excessive whites, these where dogs with 25% or less color showing). As research evolves so will the terms we use. S1 and S2 are now called Si's(they remain your Irish marked dogs). S3's are now SP's. and S4's are now SW(both are forms of the piebald gene). SP or SW are homozygous for the piebald gene. Two copies of the gene are present in order for the pattern to be present, or the amount of white showing. Your S, Si's(S1 and S2) dogs are dominant over SP/SW(S3 and S4) and are considered by many breeders to be a safer white marking to breed to/with.
Spotting/Piebald Pattern Gene
is a recessive, complete pigment reducing pattern gene, which removes ALL pigment to white in random unpredictable areas affected by the gene, it removes all colors to those areas affected, thus no color present, extreme whites by definition with blue eyes are partial albinos, therefore by default partial albinos must be considered a form of albinism. Blue eyes have been linked to the piebald gene, spotting gene has been linked to microphthalmia. See the prior link for spotting gene specific microphthalmia. All litter mates and parents of a blue eyed whelp pup must be considered a recessive carrier of the recessive blue eye gene. Piebald and or spotted on whites and excessive whites are homozygous forms of the piebald(SP/SW) gene. It is a recessive gene, therefore it can skip generations, and at this time can not be DNA'ed for its presence, but it is just around the corner, see our health testing page for more info. It is still uncertain if recessive carriers can or are effected by the gene linked disorders. Piebald/spotting gene effects a large majority of the canine breeds, and it is causing problems within many breeds. Some breeds more than others.

It has be scientifically proven that the more patches of color the less likely the chance for disorders. Proving once more color is a healthier choice for the breeder and the dog.
See a medical article on the spotting gene.
Breeds/ Facts about the risk of the spotting gene in many canine breeders.
Dalmatians, Bull Terriers, Great Danes, Bulldogs and many other breeds openly discuss their concerns over too much white and/or the presence of the piebald gene, below we will share just some breed clubs with open concerns.
Samoyed Club : Bichon Frise Club : Boxer Club : Biewer Club : Jack Russel :
there are many more, we just want to show you how piebald, spotting gene effects health and how some breed clubs are coping with the spotting gene

    genetic articlebreeds most affected by deafnessMITF news , breeds with congenital deafnessDr. Strain misquoted
There are many more research sites to study, but we wanted to give a starting point to find some facts we referred too.

MERLE PATTERN GENE
is a dominant, incomplete pigment reducing pattern gene, which dilutes pigmented areas of color(will not affect white) in random unpredictable areas of color that end up affected, it lightens those areas affected, thus areas are shaded, spotted with color that is darker and lighter. In a heterozygous state(one copy), it will not reduce areas to white when a single copy is present. It is a dominant gene therefore it CAN NOT SKIP GENERATIONS, it is either present or not. Meaning that the gene can be COMPLETELY removed in one generation. Puppies whelped from a merle breeding that are NOT merle CAN NOT REPRODUCE A MERLE nor will any of its offspring unless you bred back to a merle. DNA exists so breeders and interested parties can now test for it presence. You NO LONGER, have to wonder. We test our non-merle pups to confirm non merle status, prior to leaving our care. And although it is true, that merles do not skip a generation, it is Vitally important to remember that MERLES can stay HIDDEN FOR GENERATIONS. It can hide very easily on reds, fawns, creams, whites, (colors that were preferred by show exhibitors for many decades and continue to dominant the show ring) but even more easily on sables and brindles. Merle does not effect tan points. We are not sure why this is. But researchers are studying tan points and are making ground way, so we hope there will be answers soon. Remember Brindle can and does affect tan points. The merle gene has been linked to microphthalmia just like the spotting gene. See the prior link for merle gene specific microphthalmia.
Did you know?
there are 6 types of merle genotype: phenotype

mm-homozygous wildtype : non-merle(all canine carry the m genotype)
Mm-heterozygous merle: merle
MM-homozygous merle: double merle(UNWANTED type)
M[c]m-heterozygous "cryptic" merle: non-merle
MM[c]-heterozygous "cryptic" merle: merle
M[c]M[c]-homozygous "cryptic" merle: non-merle



CONCLUSION
Both the spotting pattern and the merle pattern SHARE the same HEALTH concerns from what we know by the end of 2008, by watching your patterns and amount of color, and where color is found on your breeding stock, and avoid breeding two copies of either pattern you will see a large reduction in the % of health issues to NONE at all. REMEMBER Chihuahuas don't seem to have the same incidence of occurrence like other breeds are showing. Researchers are still working on the genes, it may prove to be a modifier that is linking to either the spotting gene or merle gene, that will be identified one day and can be totally avoided all together.  Until then test, screen, and breed to the BEST OF YOUR ABILITY, watch your PATTERNS to ensure HEALTH. Breed away from Blue eyes, White patches over the eye, or White Hairs into the ear canal.  Place mismarks in loving pet homes unless you find a breeder knowledgeable in canine genetics, Do what other breeders in breeds that carry both patterns do, Mismarks go to loving pet homes, or genetically aware homes only. Some examples are the Aussies, Collies, Shelties, Boxers, Danes, Dachshunds, etc.


BREAKING NEWS!!!

Recessive Blue Eyes, Self Colored Eyes, Merle Eyes

Recessive Blue Eyes:
Blue Eyes are a recessive gene, that have been linked with the piebald gene, and two disorders blindness, and deafness. It also is considered by some researchers as a form of albinism, and pigment on CERF exam in some cases will be missing! Normal colored eyes with SP/SW carrying dogs have had rare intense's where they are lacking ALL PIGMENT behind the eye! These eyes and recessive blue eyes do test NORMAL FOR CERF. That means there is no abnormalities to the eye, or vision. However, in some breeds they are finding abnormalities on CERF exams. The gene is the same no matter the breed, so we do need to CERF all our Chihuahuas.

Recessive blue eyes can be bilateral, unilateral, partial, flecked, specked. Recessive Blue eyes are currently being linked to the piebald gene or spotting genes SP/SW. Because it is recessive it can skip generations. It is unknown at this time if recessive carries are or can be affected by disorders associated with the gene.

Self Colored Eyes:
These are eye colors of your chocolate, blues, creams, and any self colored dogs. Examples of this are: light brown for a chocolate is anticipated and accepted, Blue or hazel on a blue Chihuahua would also be expected. Creams, reds that are self colored also could have light brown, amber, to a dark amber eye. 

The darker the eye, the more preferred the eye. It is near impossible to get dark eyes on self colored dogs no matter what breed they are. If it happens that you get dark eyes on a self colored it is strongly preferred.

Merle Eyes:
Merle Eyes are eyes where the merle gene has affected the eye pigment. Causing the pigment to become reduced in different regions and shades in the eye. Merle eyes can be bilateral, unilateral, partial, flecked or specked. Merle eyes are not a form of albinism. And pigment on CERF exam will still be noted behind the eye. Merle eyes do test NORMAL FOR CERF. That means there is no abnormalities to the eye, or vision.

***It is important to know that NOT all merles have merle eyes, some do some don't. Just like with the sow's(spotted on whites) or excessive white Chihuahuas, not all Spotted on Whites, or Whites will have blue eyes. In fact it is quite the opposite. It is simply something that can occur in each pattern. Remember that Merle Chihuahuas can also be carries of recessive blue eyes. Pick your breeding stock carefully to avoid adding more things with each pattern that you'll want to screen and/or watch for(WHY MAKE IT HARDER THAN IT NEEDS TO BE).  Blue recessive eyes can skip generations, Merle eyes are result of a dominant gene and can only occur on a merle dog. Therefore, it can not skip generations.***


:see the Chihuahua Breed Standard on eyes. It changed in 08':

 Chihuahua Standard
PER THE CCA
note it is now a series fault if a Chihuahua has two different colored eyes or two different colors within one iris. And Blue eyes are also now a series fault. HOWEVER THEY ARE NOT A DQ.
BREED STANDARD PER AKC WHICH FOLLOWS THE CCA (PARENT CLUB)

There is question I get asked alot: since self colored eyes are allowed, merle eyes on a merle are self colored and in most all other AKC breeds are considered to be self colored, is a merle eye then not acceptable without being considered a serious fault. We can not answer this for you at this time. It will be up to each individual judge, you and the dog to discover. If you want to be sure, pick a merle with 2 dark eyes. If it is an outstanding specimen then consider showing him/her as each dog will have its own faults to work off of. Blue eyed dogs continue to Champion.

~Just because you have a recessive blue eye or merle eye, it doesn't not mean your dog will not pass a CERF eye exam, if fact we have never had a Chihuahua not pass the CERF test. However, we have had non merle lines, that carry the Spotting gene with absolutely NO PIGMENT behind the eye. Had we not CERF tested these non merles they could of been breed to a spotted on white, certain shades of merle or a dilution carrying Chihuahua. That would of been a mistake.~

Avoid Starburst patterned eyes whether merle eyes, blue eyes or normal colored eyes, they have the highest incidence of visual field loss.

***PLEASE CERF TEST***
it will help stop the spread of disorders
Recessive Blue Eye
The above eye is of a long coat Black Tri, NON MERLE LINE, year old Chihuahua. He has bilateral recessive blue eyes that are flecked in a circular ring. His bloodlines contain several Spotted on White Breeding's to one another. He is out of well known Canadian Champions lines.

He had no visual disturbances. We are unsure if he has been CERF'ed yet; HOWEVER HE NEEDS TO BE CERF TESTED. HE IS OUT OF A SPOTTED ON WHITE GRAND CHAMPION SIRE.

In 2008, He became a Champion.
HE NOW IS ALSO A GRAND CHAMPION
Merle Eye
This is a smooth red merle Chihuahua puppy. She has a Unilateral flecked merle eye which only has one fleck in her left eye in the 4 to 6 O'clock position. The rest of her bilateral eyes are very dark brown. 

She PASSED her CERF EXAM. 
SHE IS NORMAL BILATERALLY.
SPOTTING GENE & MERLE GENE
PATTERNS
Health Gene
I contacted Health Gene on 12-15-08, and they confirmed at the end of Dec. 08', they will be offering DNA testing for the Spotting Gene for some breeds. 

When asked if Chihuahuas are included in breeds being offered the testing, they informed me not at this time. For those of us with other breeds or friends with the piebald gene, please share the news! I will be watching and hopeful for news that the Chihuahua has been added.
MERLE PATTERN
SPOTTING PATTERN
THE QUESTION OF PURITY
GenMark
effective in Dec 08' has 
DNA tests on 
HOLD