Chihuahuas are small dogs belonging to the toy group originating from Mexico. The chihuahua has several breed standard accepted colours and markings. The dog is hardly ever bred for a specific colour because some colour genes are known to cause health problems. Some colours are more commonly seen than others and the spectrum of the different colour categories varies widely.
The colour combinations in chihuahuas are determined by recessive and dominant genes. The dominant colour genes and basis for all chihuahua colours are black, black and tan, chocolate and chocolate and tan. Adding recessive colour genes that dilute the dominant colour in varying shades results in over 29 American Kennel Club (AKC) recognised chihuahua colours. Since there are hardly any restrictions on chihuahua colour set by kennel clubs, breeders consider health rather than colour, and there is no true rare chihuahua colour.
While the name sounds exotic, the blue chihuahua is not actually blue but varying shades of black. The diluting gene can create from a dark grey to a light silver which in certain light appears shades of blue or lavender. The blue chihuahua can come with a variety of markings including blue and tan, blue sable and blue and white. Because both parents of a blue chihuahua need to carry a recessive gene, they are harder to breed and are less common than many of the other colours.
Merle is a colour commonly found in Australian shepherds and border collies. A white coat is mixed with spots in a completely random pattern and usually produces different colour eyes. Merle chihuahua spots can be red, blue, chocolate and sable. Merle is the only less common colour not recognised by the AKC, and many other clubs see it as a deterrent to breeding because the genetic combination almost always results in hearing and vision problems.
Brindle is a common colour in boxers and pit bulls that looks similar to a tiger's stripes. The darker and lighter colours of the coat alternate creating a striped effect. A brindle chihuahua is less commonly seen but can be red, fawn, chocolate or a blue-based brindle with or without white markings on the paws and chest.
Although black is one of the primary dominant genes determining chihuahua coat colour, it is rare to find an all-black coat. The black gene is seen in multicoloured coats and can manifest in mask markings, but the two dominant black genes needed to create a solid black chihuahua is very uncommon.