Updated date:

The Dangers Hidden in a Puppy's Coloring

An Australian Shepherd with Persistent Pupillary Membrane, a possible side effect of poor breeding.  (Photo: ASHGI.org)

An Australian Shepherd with Persistent Pupillary Membrane, a possible side effect of poor breeding. (Photo: ASHGI.org)

A gorgeous "double merle" dog.  He was deaf and was lost to cancer after his sixth birthday, possibly because of his genetics.

A gorgeous "double merle" dog. He was deaf and was lost to cancer after his sixth birthday, possibly because of his genetics.

An Unknown Danger

Many people hope that their puppy will be happy, healthy, and well-adjusted. We invest in training, get all the vaccinations and toys, and even do some research.

What we don't always realize is that a hidden health risk can be written all over our pup, and we might not even notice!

While not always the case, there are certain risks associated with the coat color called "merle," especially when the pup comes from a disreputable breeder (which means that he is breeding only for money and without regard to the health of his animals).

Too many people are confused about the specifics of this problem, sometimes assuming that dogs with a lot of white and blue eyes are deaf, or sometimes not understanding that there is any risk involved at all with the breeding of these dogs.

What Does Merle Look Like?

Merle is a gorgeous coloring pattern found in the breed standard of many breeds of dogs. Among some of these breeds are: Australian Shepherd, various Collies, Catahoula Leopard Dog, Welsh Corgi, and the Shetland Sheepdog. It's also sometimes called "dapple," mostly in Dachshunds.

A merle dog usually has a single-colored base coat with different-colored speckles, spots, or patches. The merle gene can also cause a dog to have blue or multi-colored eyes and/or foot pads with patches of pink and black.

What Causes Merle Coloring?

In order for a pup to come out merle, at least one of his parents must be merle. One merle parent, though, does not necessarily guarantee any merle puppies. As with most genetics, it is often luck of the draw.

Because of this, the merle pattern is often considered more "rare" than other possible colorings in any one breed. And rare -- because of supply and demand -- usually means "worth more money" to breeders, both responsible and otherwise.

Why not just breed two merle dogs together, then? This would ensure that there would be at least some merle puppies, right, and therefore the breeders would make more money (or charge less)?

While, yes, breeding two merle dogs often results in many merle puppies, the results are almost never desirable. This is because, statistically, a quarter of the produced puppies will be "double merle" or "lethal white" (another quarter will be non-merle, and the last half will be single merle).

The above photographs are copyrighted property of Red Dog Photography. They are photos of a merle mother dog and her litter double-merle puppies.

Why "Lethal White"?

The problem with these double merle (or double dapple) dogs is not in their gorgeous coats, but it is in the genetics that cause them. See, the genes that determine a dog's coloring also have a huge role in the development of his hearing and eyesight.

Lethal White in a dog is not actually deadly, unless you count the pups that breeders "cull" (euthanize after birth because of an unwanted trait). It also rarely results in an entirely white dog; usually a double merle pup will have at least patches of merle somewhere on its body. The title, therefore, is really a misnomer. The dogs are usually neither white nor doomed to an untimely death because of their genetics.

But misnomer or not, it can cause serious problems for the pups in its category, namely deafness or blindness, and even both! Pups born "lethal white" can also have malformed eyes or no eyes at all.

Disclaimer: "Lethal White" in dogs is very different from Overo Lethal White Syndrome in horses; the causes and effects of the two are completely unrelated to one another.

What's Wrong with a Deaf or Blind Dog?

Thousands of American families have dogs that are deaf, blind, partially one of the two, or any combination thereof. Handicapped dogs make great pets once you learn how to accommodate them.

This means that adopting a puppy deemed "lethally white" is not a bad idea; you just need to understand the risks and be prepared to deal with them. Double merle (or "double dapple") pups often have gorgeous color patterns, too.

So there's nothing wrong with a deaf or blind dog... as a pet.

But no breed club or registry will accept a genetically deaf or blind dog in its conformation ring. After all, a dog that has a genetic defect is not showing the standard of the breed.

This means that no reputable breeder would ever allow two merle dogs to mate and produce puppies, even if they try to convince you that it is "safe". The risks are too great to them. A huge red flag should shoot up if you encounter, say, an Australian Shepherd "breeder" with all merle pups and adults. Do your research, and never support the creation of sick animals with backyard breeding and puppy mills.

So What to Do?

The only way to eradicate merle-to-merle breeding is to never endorse disreputable breeders who are only "in it" for the cash they can make off of these "rare" dogs.

Remember, this genetic problem is completely avoidable through responsible breeding practices. And while a dog with a genetic defect does not necessarily make a worse pet, it should never be intentionally bred now that we know about these dangers.

More Scientific Explanations

  • Homozygous Lethal White Merle
    An article mainly about Australian Shepherds, it applies to all "double-merle" dogs with a better explanation of the genetics of the problem.
  • The Double Dapple
    The Dachshund equivalent of the above link. This article goes further into detail about the behavior of the merle gene in breeding.


Skye on October 02, 2016:

Just read a Comment by Lisa S. She said that if the dog does not express the Merle gene then it is not Merle, and that 2 dogs that do not express the Merle gene cannot produce Merle pups, Merle grandparents or otherwise... This is not entirely true. While it IS true that Merle is a dominant gene and that I have never heard of a recessive Merle gene, there are some dogs where the Merle gene they have is shortened causing them to either show very little Merle or none at all either because any Merle they would have had has been masked by white markings or the Merle was simply not physically present. These are called Cryptic Merle's. Cryptic Merle should be tested for in any apparently solid coloured dog intended for breeding that comes from a Merle background because, while 1 Cryptic Merle gene and 1 Merle gene in the same dog has no ill effects (2 Cryptic Merle genes in the same dog also has no ill effects), the Merle gene that the Cryptic Merle dog has could lengthen in its offspring, leading to double Merle pups if a Cryptic Merle is bred to a Merle.

Also, there are Hidden Merle's as well as Cryptic, however Hidden Merle's occur when the Merle gene is put over pale coloured dogs like, Red, Fawn, Cream, Gold etc. The dog in question can have the Merle gene without physically expressing it. Blue Merle is the Merle gene over a black dog which effects the black parts of the coat while Red Merle is the Merle gene over a Chocolate dog which effects the chocolate parts of the coat.

Sis on August 12, 2015:

What would cause a piebald Aussie mom red tri dad blue Merle ...faces and ears marked perfectly but bodies a lot of white with spots?

brunette_baby124 on February 11, 2015:

So the Merle gene isn't actually bad for a dog's health in any way? I was thinking about adopting a Merle Australian Shepherd when I read your article. I got a black and white one instead, as I don't have a lot of money to spend on veternary assistance.

Thank you,


aqhlovr on May 14, 2013:

Lisa S...so how can two black/whites with no merling produce 4 merles in 1 litter? Someone above (pastor's wife) posted about the litter of borders they looked at.

Jaedyn Calcagno on January 27, 2012:

The reason of the first picture could be from genetics, like you said, or from a problem I heard. If you breed two blue merle's together the pups can be born with eye problems or even without eyes!

kieran mallon on September 23, 2011:

had the dog and was deaf and blindness set in was only a pup but we still had fun with it but when it hit a year old mental problems set in and was always chaceing shadows and walked up and down in a line or went round in circles was very sad had to put the reflaxs went to and she was not getting any rest so had to put her down very sad so be carefull

Lacy on May 25, 2011:

Hi, I was wondering if I bred my red merle aussie/border collie mix to a blue merle australian shepherd, would this produce the double merle since they are different colors and also since the border collie gene will be in the mix too?

kdkf on November 22, 2010:

what hapent with the eyse

V on August 10, 2010:

Thank you so much for the information. I recently got a merle puppie from the pound and we've been trying to figure out what seems to be the problem with him... He has the exact same thing! We will talk to the vet and try to help him live a long happy life even with his disabillity. Thanks a million!!! :)

helenathegreat (author) from Manhattan on June 15, 2010:

Lisa S, you are totally right. I was confusing the merle gene (which is dominant) with the piebald gene (which is recessive). Thank you so much; I'll correct this hub right away!

Lisa S on June 15, 2010:

There is no such thing as a "recessive" merle gene. You are taking advice from someone that doesn't understand the merle gene at all. :D Merle gene is or isn't ,,period. If it's merle,,,it has the gene...if it's not merle..it doesn't have the gene. Merle X Merle does have a higher risk of deafness/blindness due to the fact that there is too much white sometimes in the ear/eye area. Lack of pigment in the ears, eyes can impede development. It certainly isn't a good idea to breed Merle to Merle, BUT a non merle patterned puppy out of merle parent does NOT carry merle. If it doesn't look like a merle,,,,it's not a merle. Research research research.

Also note that merle is NOT a color at all....it is a pattern spread throughout whatever color is already there. Example... a 'blue merle' is a black dog with the merle pattern.

To ad...I do not breed double merles in any breed. I do not advocate the breeding of double merles in any breed. I am simply correcting some misinformation given with the best of intentions. :D

Closing....Merle gene is NEVER , EVER, EVER, recessive. No such thing. Dominant only. It either is, or isn't. A non merle patterned dog cannot EVER produce a merle patterned dog unless bred to a merle dog. period. ever. never. :D It doesn't even matter if it's dam was merle,,or sire,,or grandma,,or grandpa. If IT'S not merle, it won't produce it.

Shawn on May 03, 2010:

This is another reason to adopt a shelter dog! I have a purebred double dapple from a pet store. I had no idea when I bought her, I was contributing to a VERY bad breeding practice among unethical breeders. Shelter dogs are JUST as wonderful and who knows what all this "designer" breeding will eventually produce. I now believe no one should be selling dogs until the shelters are empty! I am completely reformed forever! Wacky breeding also produces still-born pups. Think about it.

helenathegreat (author) from Manhattan on November 13, 2009:

Wow, Erin, what a great story! Not everyone would have been as brave to stand up to the breeder like that. I'm glad you're willing to give a loving home to that beautiful puppy, and hopefully the "breeder" will think twice next time?

Erin on November 10, 2009:

Hello, I just adopted a little 4 month old double dapple dachshund girl. As soon as I saw the puppies I KNEW they were double dapple and I shouldn't support this breeder. But the poor baby had deformed eyes and was just the sweetest puppy I have ever met, and I feel like its not the puppies fault the breeder doesn't know! So I educated the breeder (not sure how much good that will do!) and she told me I could just take the puppy if I promised to give her a loving home, So I did! She still deserves to be loved! =] but I wish there was more I could do about that "breeder"

but anyways! Wonderful read and very informative!

raisedbydogs on October 26, 2009:

i grew up with an aussie, Lacey, born with no eyes at all. Her mother was almost completely white, and the father was merle. We rescued the entire litter and the bitch after we found the owner was regularly drowning pups born with the "lethal white" problems.

Despite her blindness, Lacey was an incredible dog. She loved to run and play on the farm, adored people, and was an avid (and surprisingly successful) rabbit hunter. She only ever ran into things when she got soo excited at meeting new people. She lived to 12 or so and was by far one of my favorite dogs. The only sad thing was that she loved to play fetch but often couldn't find the sticks. We got her a ball with a bell, and she loved to chase it and play soccer even when she was quite old.

Her eyes never caused her any pain, and she was a much loved member of my family for many years.

helenathegreat (author) from Manhattan on September 16, 2009:

Hi Donna, thanks for writing. The parents both being merle carriers should not create genetic problems in your dog. Of course, you can't guarantee against other genetic issues, but those puppies cannot be lethal white because of the way genetics work. Hopefully you're buying from a good breeder, though, who should be able to walk you through all of the rest of the possible genetic issues your purebred dog could have. Good luck with your new family member!!

donna on September 15, 2009:

We looked at border collie puppies tonight. Expecting to see all black and white dogs we were surprised to see 4 blue merles, two black/white/tan and one black/white. The breeder offered us pick of the litter since my husband is her pastor and our beloved collie died 2 months ago. The mother is only black/white, with one merle parent. The father is the same combination. Are the health risks still higher with the parents both being only black white with one merle grandparent each?

Many thanks


helenathegreat (author) from Manhattan on September 11, 2009:

I'm not sure what you mean, ezguides. I don't think it's "racist" or "breedist" or anything. Did you read my hub? It's about genetics.

ezguides from Boston on September 05, 2009:

Mnn...I can't help but think it's kinda of "racist" to hub about this.

Eternal Evolution from kentucky on August 20, 2009:

Interesting hub. I knew that white dogs are prone to deafness and or blindness but never knew about the merel coloring.

helenathegreat (author) from Manhattan on March 11, 2009:

Hi Jen, thanks for reading! I haven't read that, and I'm certainly not a geneticist, but that does sound completely possible.

Jen on March 10, 2009:

I thought I read somewhere this DD combo could result in heart or liver/kidney problems too. But now I can't find a refrence. Is this true?

helenathegreat (author) from Manhattan on July 28, 2008:

Hi steven, thanks for the comment! Make sure to check out my hub about finding a reputable breeder... they'll make sure to look out for all the other breeding problems that you might not know about, too! https://hubpages.com/animals/ReputableBreeder

stevenschenck from Sacramento California on July 26, 2008:

Thank you very much for this information - we are looking at Ausie Shephers right now to replace our loved dog that just passed and I had no idea about lethal white.

helenathegreat (author) from Manhattan on May 01, 2008:

The main thing to do, welsh corgi checks, is to never breed two merle dogs together! This is just one more reason to leave breeding dogs to the professionals; you don't know if your dog is carrying the recessive merle gene unless you know all about his lines. It's more work than a lot of people seem to think! Thanks for stopping by.

welsh corgi checks on May 01, 2008:

omg, i've never realized this kind of skin disease in dogs until now. at least, this hub is very helpful in making me realize this "merle" & how it can affect our poor dog's health. I will be wary this time in choosing a breeder. thanks for the hub, helenathegreat! btw, you can visit this site and preserve your dog's "youthfulness" with these nifty items! Check it out! I'm sure you'll love this!


helenathegreat (author) from Manhattan on April 06, 2008:

Well thanks for reading, Lilie! I appreciate your kind words.

lilie on April 06, 2008:

hello im a big fan of yours thank for helping dogs

helenathegreat (author) from Manhattan on March 08, 2008:

A merle/sable combination CAN produce "double merle" puppies, Shawna, if the sable dog had the merle recessive gene, which he may well might have.

But even if your dog is double merle, that doesn't mean he's deaf. And even if he's deaf, that doesn't mean he won't be the best dog ever!

Have you clapped or made loud noises behind him, so he couldn't see you? Did he react? He might also be partially deaf.

Here's my recommendation: Talk to the breeder, if you can, about testing for deafness. Ask your vet, too. He might be a very mellow pup, might be deaf, or might be partially deaf. Then I suggest you join the Yahoo groups group for people with deaf dogs. I'm not sure what it's called, but it is an EXCELLENT resource. People will give you tips for training and communicating; I think you'll find that a deaf dog is not too much different than a hearing one, and that community will help you through any bumps you might hit.

Thanks for asking the question, and if you have any more, please let me know!

Shawna on March 07, 2008:

I just bought a merle puppy. The mom was a merle and the dad was a sable. I have read that is not a good combination. My puppy does not seem to hear. My vet seems to think he is fine, but he does not even look at me when I talk to him. He is 9 weeks old, and I feel bad for him. What do you think? Can my puppy hear? My 8 year old shelti is so alert, but I did not raise him as a pup.

helenathegreat (author) from Manhattan on February 12, 2008:

Thanks, wychic! Plenty of double merles are perfectly healthy, as it seems yours is, so it's never a bad idea to adopt one... just a terrible decision to breed them! Thanks for the comment.

Rebecca Mikulin from Sheridan, Wyoming on February 12, 2008:

Great hub! One of my dogs (a rescue) is a double merle and luckily as far as we know she doesn't have any hearing or eyesight problems but it's good to know the color can have problems.

helenathegreat (author) from Manhattan on February 12, 2008:

Oh, I see how the title would make you think that... Think I should change it to be more accurate? (Thanks for commenting, by the way!)

Whitney from Georgia on February 12, 2008:

Very interesting. Although, I was thinking I would find more information about health concerns with different colored dogs. Like how solid white dogs are prone to getting sunburnt. I definitely wasn't expecting merle. Ha. Very nice hub either way.

Related Articles