Merle Pit Bull
If suddenly someone stops you on the street and ask you which dog is considered the most dangerous, you'll most likely answer without hesitation – the pit bull terrier.
Pit bulls don't have a good reputation because of its complex nature. Once upon a time, it was bred for dog fighting which means it's more prone to aggression than other breeds of dogs.
However, with regular training, pit bull puppies grow up to be loyal, reliable and friendly companions.
For quite a long time in different countries of the world, breeding these dogs was prohibited. So they are quite rare.
However, some Pit bull terriers are considered rarer than others because of the difference in their color.
Merle is a special, very rare coat pattern in which the hair is colored unevenly. Simply put, it looks like the dog was sprayed with dark paint to give him spots.
Despite the fact that merle pit bulls look incredibly impressive, the breeders are not in a hurry to spread them.
Moreover, in certain professional circles, dogs with this pattern are even considered prohibited.
The fact is that the process of pigment formation in the dog begins at the embryo stage at the same time when the nervous system is forming.
Merle is in fact a genetic defect in the coat pattern that is at a certain stage of the embryos development, there was a failure.
It affects the animal as a whole so these dogs almost always have nervous problems.