Jack Vanderwyk’s article on Dilutes

The Silver Labrador - A Trojan Horse

Following recent Kennel Club actions (in offering “silver” as the first colour option when making an online application to register a litter on their new website), and in grateful tribute to Labrador enthusiast, Jack Vanderwyk, who sadly died in August 2016, I am delighted to republish below Jack’s excellent article on this topic, which he kindly wrote for the Club’s 2015 M.C.L.R.C. Yearbook. Readers will note that references in Jack’s article relate to circumstances at that time.

The Kennel Club Registers Dilutes as Purebred Labrador Retrievers –A Trojan Horse

Caroline Kisko ([then] Kennel Club Secretary and Communications Director) has admitted that The Kennel Club will register any pups from KC registered parents, whether they are black, yellow, chocolate, ‘silver’, ‘charcoal’ or ‘champagne’. Furthermore, these diluted dogs can be entered in shows. The Kennel Club leaves it to the Judges to decide whether these dogs meet the standard.

Our first problem is that the dilution gene (d) is alien to the Labrador Retriever breed. The dilution gene originated in a shabby puppy mill in the United States several decades ago where several pointing breeds were running loose together. In an effort to create a “pointing Lab”, the dogs were allowed to cross breed with Labradors. One of these breeds was the Weimaraner, and many of the diluted “Labradors” we see, especially those of the past, resemble the Weimaraner in several ways. It’s not only their appearance and behaviour, but also their diseases, which shouldn’t be introduced to our bloodlines.

Various expressions of the dilution gene have been noted. Some dogs with dilute colour display minimal or no health problems, other dogs experience hair loss and skin problems. Colour dilution alopecia (CDA) and black hair follicular dysplasia (BHFD) can accompany coat colour dilution. These diseases cause recurrent skin inflammation and drying, bacterial infections of hair follicles and severe hair loss. Late 2013 a 12-week-old female silver Labrador Retriever was submitted to the Comparative Ocular Pathology Laboratory of Wisconsin and was diagnosed with Malignant Uveal Schwannoma. Scientists believe that the dilute colour mutation may contribute to the cause.

Other disorders that could travel with the dilution gene are heritable Weimaraner genetic issues such as trembling disorders, autoimmune related vaccination sensitivity and intolerance, Von Willebrands Disease, hyperuricosuria causing painful bladder and kidney disease, and behavioural problems that are more common in the Weimaraner, such as separation anxiety, and dominant, protective, territorial temperament. Minimizing occurrence of these conditions would mean minimization of the dilute mutation. Selection against dilution is important in breeds that display health issues associated with the mutation. It is also important

to minimize the dilution mutation in breeds that do not have a standard written which include these colours. The Labrador Retriever is currently one of these breeds. Dilute coloured Labrador retrievers are a disqualification according to breed standards. Those dogs carrying the dilute gene should not be registered as purebred Labrador Retrievers.

The Labrador Retriever Club Inc. is the AKC Parent Club of the Labrador Retriever. On May 12, 2014, the LRC published the following message on their website: “Very exciting news – the OFA has agreed to maintain a database of Labradors who have been permanently identified (microchip or tattoo) and have been tested for the d gene. Dogs having the genotype dd will be listed as affected, Dd as carriers of the dilute gene and DD as clear of the dilute gene. This is great news for us.”

Note: The Orthopaedic Foundations for Animals (OFA) only registers hereditary diseases (or the lack of those) in their databases. So, it’s not a simple matter of “a different colour”.

Our second problem is the fact that The Kennel Club has already registered 400+ dilutes as purebred Labradors, some as “Colour Not Recognised”, but all of them without any restrictions with regard to showing, breeding or anything else for that matter. These dogs are now part of the Labrador gene pool in the United Kingdom.

Our third problem is the fact that not all of these dilutes are affected by the dilution gene. Many of them are “only” carriers of the dilution gene, which means that they are able to produce dilutes. So not only could these dogs enter shows, but they could also come to your doorstep for a mating with your Champion stud. Many breeders have been duped this way and were unpleasantly surprised to see that their Champion is the sire or grandsire of diluted puppies.

What can we do?

While DNA-tests are increasingly used as a valuable breeder’s tool, we can easily and reliably test Labradors for the dilution gene. DD is the only acceptable result, as Dd is a dilute carrier and dd is affected by the gene. So, any bitch you don’t know, which comes to be mated by your stud, should be tested for the dilution gene.

Of course, The Kennel Club should require all imported “Labradors” to be tested, but they don’t. Despite the fact that we have been able to show the presence of the dilute gene in DNA since 2007, the Kennel Clubs just look at the phenotype of a Labrador, not at the genotype. So, a dilute who only carries the dilute gene without being affected by it, will be seen as a purebred Labrador, while a simple and inexpensive DNA test would show it is a Dd, able to produce dilutes eligible to be registered as purebred Labradors.

And then there are the online LRCN and LabradorNet Databases, in which you can find the “Labradors” carrying, or affected by, the dilution gene. Note: not all of them are registered in the database, but most of their ancestry is. Studying pedigrees might give you an indication. From a showing point of view it would be helpful if there were an addition to the standard, such as “any colour other than black, yellow or chocolate is considered a disqualifying fault “.

Last but not least, there’s the organised Labrador world. There is so much that should have been done, and so much more we can do. It all depends on the people we elect in the committees and the Labrador Breed Council. I refuse to believe that, in the end, a Kennel Club is able to decide something which dramatically affects the future of the Labrador breed, very much against the will of the Labrador Clubs and the Breed Council. Jack Vanderwyk

COAT COLOUR GENETICS FOR THE DILUTE GENE IN LABRADORS D Locus (DNA marker tested – C.22G > A) Associated with the dilution or lightening effect of solid colours, with D being the dominant allele, the dd genotype results in the diluted effect (like grey, blue, silver, lilac and champagne).

Possible Genotypes: DD – does not carry the dilute, has 0 copies and will NOT pass dilute to offspring.

Dd – dilute carrier - has 1 copy of dilute d, and 1 normal allele D, has 50% chance of passing dilute to offspring.

dd – dilute phenotype - has 2 copies of dilute dd, will display dilution in their own coat and will ALWAYS pass dilute to any offspring.