<P> The typical fine, straight, and silky Yorkshire Terrier coat has also been listed by many popular dog information websites as being hypoallergenic . In comparison with many other breeds, Yorkies do not shed to the same degree, only losing small amounts when bathed or brushed . and it is the dog's dander and saliva that trigger most allergic reactions . Allergists do recognize that at times a particular allergy patient will be able to tolerate a particular dog, but they agree that "the luck of the few with their pets cannot be stretched to fit all allergic people and entire breeds of dogs ." The Yorkshire Terrier coat is said to fall out only when brushed or broken, or just said to not shed . Although neither of those statements agree with what biologists, veterinarians, and allergists know about dog fur, allergists "think there really are differences in protein production between dogs that may help one patient and not another". </P> <P> The Yorkshire Terrier is a tan dog with a blue saddle . Particolours exist, although they are not correct for the breed standard . The particolour coat is white with black / blue and tan . The white is caused by the recessive Piebald - gene . It is very rare to get a particolour, and if one is found, it tends to be very expensive . Some Yorkshire Terriers are solid golden, they only produce pheomelanin, others are liver or chocolate, a brown colour; they only produce brown eumelanin but are unable to produce black eumelanin . The breed is defined by its colour, and such non-standard colours may indicate health problems or cross-breeding with other breeds of other colours . The AKC registration form for Yorkshire Terriers allows for four choices: blue and tan, blue and gold, black and tan, black and gold . Colour alone will not affect whether or not a dog is a good companion and pet . Even though off - coloured Yorkshire Terriers are advertised at premium prices, being of an unusual or atypical colour is neither new, desirable, nor exotic . </P> <P> Until recently, mismatched Yorkshire Terriers could be crossed with Biewer Terriers, a new breed originated in Germany from particoloured Yorkshire Terriers . Although the American Kennel Club will not deny registration of a Yorkshire Terrier on colour alone, meaning that particolours are now registerable with the AKC, the Yorkshire Terrier Club of America has a directive that "any solid colour or combination of colours other than black and tan" for adult dogs is a disqualification, and "dogs of solid colour, unusual combination of colours, and particolours should be disqualified ." </P> <P> It may take three or more years for the coat to reach its final colour . The final colour is usually a black / grayish colour . P.H. Combs, writing in 1891, complained about show wins awarded to puppies, when the dog's coat does not fully come in until three or four years old, "and the honor of winning such a prize (for a puppy) can therefore be of but little practical benefit to the owner" since the adult dog's colour cannot be exactly predicted . </P>

When does a yorkie puppy become a dog