Merle Coat Colour in the Chihuahua
At its meeting on 6th January, the General Committee approved a ban on the registration of Chihuahua (Long or Smooth Coat) puppies sired or whelped from a merle parent. This follows representation from the British Chihuahua Club and will be effective from 1st March 2009. No puppies from matings which take place on or after this date which involve a merle parent will be accepted.
This announcement is in addition to the press release issued in July 2007, where it was agreed that merle puppies would no longer be registered due to the possible health problems that are associated with this colour, which does not exist naturally in the breed.
Previous information relating to the merle colour indicated that this colour could only be produced as a result of a dominant gene. Therefore, the merle colour could not be carried without it being exhibited in the dog. However, the British Chihuahua Club provided evidence from Genmark, an American company confirming that ‘cryptic’ merles exist, whereby a dog could show no outward appearance of being merle but could still be carrying merle.
Merle Bull Terriers
At the request of the Bull Terrier Breed Clubs, the Kennel Club has agreed that it will no longer accept the registration of any merle Bull Terrier puppies produced from matings which take place on or after 1st March 2011.
Coat colour in the Bull Terrier is complex because a range of colours is acceptable. Merle patterning, patches of lighter colour appearing in the coat, is the result of the M gene in the dog. There are two alleles of this gene: MM (merle) and M+ (non-merle), with merle (MM) being dominant to non-merle (M+). In some breeds, the effect of the merle allele (MM) is termed ‘dapple’.
Unfortunately, the effects of the merle allele (MM) are not confined to coat patterning and we know that there can be an increased risk of impaired hearing and sight associated with it, particularly in dogs that are homozygous for MM (dogs that carry two copies of the MM allele).
However, because the colour has not hitherto been encountered in the United Kingdom in Bull Terriers, and the fact that it is not a natural colour in the breed, the General Committee of the Kennel Club has agreed that with effect from 1st March 2011, it will not accept the registration of any merle Bull Terrier puppies produced from matings which take place on or after this date.
http://www.thekennelclub.org.uk/cgi-bin ... gi?id=2249http://www.thekennelclub.org.uk/item/3510