GENETIC REGISTRY

Genetic Registry for Hairless Dogs

Genetics
Hairless Gene - about hair

Other Characteristics of pila:

The Recessive Hairless Gene

Recessive hairlessness has special traits that make it distinct from dominant hairlessness. This is true in any species that has this kind of hairlessness. A coat is grown but will be shed when some unknown factor triggers it.
In humans with alopecia, and American Hairless Terriers, individuals are born with nirmal coats or hair and suddenly the coat or hair is shed and does not grow back, leaving individuals virtually free of any hair at all.
This gene does not affect the teeth, and individuals will have normal teeth.
But some AHT and pilas have a secondary coat of fuzz that may grow in later than at birth and will be shed eventually.
pilas have had eons to develop genetic diversity and some forms of this secondary coat are not shed for many years. This coat is often seen as curly reddish or white fuzz on the hairless part of a hairless dog, and is often lost by one or two years of age.
Some dogs may be very hairless and grow fuzz late in life around the face or on the body.
It is likely that the genes responsible for growing and losing an undercoat in normal double coated dogs, is involved in the recessive hairless complex or set of genes.
This extra body hair is often associated with red or blonde hair, and the true black Xolo hair (on the head of hairless dogs or black coated Xolo) restricts the growth of extra hair. Xolos may have the genes for the fuzz but never grow it until the dark dog is mated with lighter colored one. The offspring without the true black hair may develop fuzz.
In pilas the true black is even more restricting, and when it is present it may restrict almost all the hair producing the PIO (Peruvian Inca Orchid) type of dog without hair on top of the head.
One could think of pila genes as producing variety on both sides of the Xolo traits - a Xolo should have short hair on top of the head - pila may have long or fluffy hair or no hair at all. Either pattern should be seen as pila and not Xolo.
Please remember that all these dogs have been registered as Xolos and are considered Xolos - we are speaking about the genetics traits not the standard created by people to breed dogs to their taste.
Understanding the genetics makes it easier to breed for the puppies you want and not get surprises.
pilas as pups have distinct traits - in some lines. Puppies may fall off of beds or couches if not watched - EVERY SINGLE TIME. Puppies and young dogs may have very different droppings from Xolos. They will not be firm and may have a stronger odor. The pups may not have 'sphincter awareness' until 6 or 7 months and may not be aware they are making dotted lines across a yard. The pads of their feet may need constant washing. And they may have one play game - shredding everything in sight. THIS TRAIT IS INHERITED AND DOGS LIKE THIS SHOULD NOT BE BRED ROUTINELY! A litter of such puppies should not be placed in homes until their brain and sphincter clicks in, and should be spayed or neutered.
This trait was the reason for so many beautiful standard Xolos being found in shelters in the 1980's - by the time they were adopted they were normal and no one could understand why they had not been claimed by the original owners.
Luckily most pila come out of the nest at two or three weeks to do their business away from it - and if they can get outside themselves they may not even need paper from a very young age.
This is a trait that we find in most Xolos, one that makes training simple and is associated by other very convenient and moral thinking patterns.
Some pila types may have a gene set associated with short or partial length tails, and rear dewclaws. If bred to a second generation for type, the rear paws may have toes like tiny hands with the dewclaw like a little thumb, connected and functional. Such dewclaws should not be removed but are a mark of a historic type of dogs, and very rare. Rear dewclaws - or even front dewclaws - should not be removed if they are attached and functional. Unattached dewclaws should be photographed before they are removed to retain a record.
It seems contradictory that many pila do not climb even low fences, and the dogs i have had to take out of trees are always the Xolo phenotypes. But the fuzzyfaced dogs pictured earlier do both open gates that other dogs can not get out of.

The recessive hairless gene does not mix with the dominant hairless gene, but is expressed on top of it.
Dogs may accumulate pila genes to become more hairless or develop the powderpuff coat, and if they do not have the dominant hairless genes or lose it over generations, they will have litters of all hairless dogs, and may have complete sets of teeth. But dogs bred to be as hairless as possible for generations will lack something important, and may eventually die out. In the United States PIO have been bred to the point of near extinction due to this reason.
The dogs pictured below were turned in to rescuers because after many litters they had almost no hairless pups. Although they have hair on the head proper for Xolos, they have almost full sets of teeth.
The blond dog is a male pup that was one of the few hairless offspring. Notice he has hair on the sides of the face. In the future the younger female will be mated to a true black Xolo, which will hopefully verify the genetic theory that this will produce hairless pups by restoring the dominant hairless genes in the offspring.

Wild Card Red Hair

Occasionally a heavy-bodied red/blond fluffy hair female with a short or missing tail will be born unexpectedly in a Xolo litter. These dogs are rarely bred but become wonderful pets.
If they are bred to a Xolo without the strong true black hair, the Wild Card Red Hair gene unlocks the Xolo repression of other patterns, and a rainbow of offspring result. Few have any true black - pups born with black hair often have it change to red (if short) or blond (if long) or mixes of gray and tan and clear banding without color on straw colored hair (if fluffy).
There may be many offspring from such dogs that seem to be conforming to Xolo, but if one pays attention to some minor traits, it is clear that they have predominantly pila blood.
Many have slightly short tails and long hair on the tail that makes up the length visually. Owners often miss a color change in hair - a red-haired Xolo is born with red hair, a black-haired dog that changes to red is pila. Some may have back dewclaws. Some may have wispy hairs on the side of the face or a heavier body shape. Eyes that reflect red in the dark are pila. Some offspring may have almost no hair at all on their body. Lines with dark dogs with a bit of white markings may have a very hairless pup with charcoal skin and no white at all, perhaps a few straw colorless hairs on the feet.
People who are proud of having almost all hairless pups with no hair on the heads are proud of pila, not Xolos.
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