How is the merle pattern produced in chihuahuas?

there IS NO Merle-pattern in purebred Chis.
they can be pinto, fawn, fawn/mask, black, white, liver, any of those colors with white markings, blue, black-n-tan,… solids or pied.

there is NO BRINDLE; there is NO MERLE.
any Chi with either or those patterns is a cross-breed.
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30 yrs educating ppl, training pets;
certified Vets Asst; humane-educator

I dont know how the merle Chihuahua was bred, I dont think it is a bad thing. Other people will say so. I think its beautiful. Plus Chihuahuas come in all different colors. I have a brindle one. Just because they are brindle or merle does not mean they are cross bred. What did they do breed them with boxers? or Australian Shepherds? I dont THINK so.

ADD:
Yeah they are mixed with poms or dachshunds, yeah right!! yall are a bunch of idiots. And mine is mixed with a boxer…huh? hahahahha. Stupid.
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genetics traits
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A Chihuahua who has merle puppies, or a Chihuahua that is merle isn't completely pure-bred. They're normally mixed with Dachshunds or Pomeranians to get that color. So, basically you're paying $700 for a pretty mutt. Also, dogs with the merle gene tend to end up with hearing problems, or sight problems. You'll notice that a lot of the merle chi's are on the bigger side. I've never seen one that was small and compact, they've all had long backs. This color of Chihuahuas has only been around for so many years. Which means it's just recently been introduced from another breed.
http://www.picassochis.com/merles.htm
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