Colour Dilution Alopecia - Kennel Club webinar

This was a free webinar for owners and breeders who wanted to find out more about the dangers of breeding for fashionable colours, using the example of colour dilution alopecia - including what research has told us to date, and how best to support dogs affected with this condition.

Colour Dilution Alopecia (CDA) is a genetic condition found in some breeds that causes hair thinning and loss, which can leave the skin prone to sunburn, infection and dermatitis. The condition is associated with dogs who have a “dilute” colour (e.g. blue, lilac, isabella or silver). While the disorder is commonly described in Dachshunds and Dobermanns, it has also been recognised in other breeds. With the rise in popularity of “fashionable” coloured dogs, it’s crucial to understand the dangers that can be associated with breeding for certain colours and what breeders can do to try to reduce the prevalence of conditions associated with dilute coat colours.

The webinar shared some data on the 2021 registration statistics of those breeds where there are Non Breed Standard (NBS) colours in their registration options. This applies to about 10% of the KC’s registered breeds. At one extreme, French Bulldogs had 70% of their 2021 registrations as NBS and 53% for Bulldogs. Labradors had 1% NBS but, with over 61,000 registrations, that still amounts to over 800 NBS dogs.

Colour Dilution Alopecia is a concern to many of us in the Dachshund community because it is reported in the dilute colours (blue and isabella). We ran a breed health survey in 2021, supported by The Kennel Club, specifically to find out how prevalent the condition was. Our 2018 survey had shown skin diseases and allergies to be the second most prevalent health concern in all colours (after IVDD - back disease) and we wanted to find out if this was a particular issue in the increasingly popular dilute colours. Most people will be aware that Mini Smooth Dachshunds have grown in popularity over recent years (under 3000 registered in 2013 and over 15000 registered last year). Shockingly, registrations of dilute Mini Smooths have grown from 0.1% in 2018 to 20% last year. Not only has the breed become extremely fashionable, but “rare” colours have too (often aided by the influence of social media).

In Fitch Daglish’s 1952 book “The Dachshund”, he refers to blue dachshunds, so it is clear that the dilution gene has been in the breed for a very long time. This is not something that has been added by cross-breeding. The high number of dilute puppies now being bred is down to intensive selection for the dilute coat colour in the UK population. Our 2021 health survey showed 80% of blue dachshunds were affected by CDA and 86% of isabellas.

Dr Rosario Cerundolo (Head of Dermatology at Dick White Referrals) presented during the webinar on the signs, diagnosis and treatment of CDA. He showed examples of the condition in several breeds, including Dalmatians, Russian Toy Terriers and Dachshunds. Electron microscope images illustrated the structure of hairs in dilute dogs that causes patches of hair thinning or loss and may also include flaky and/or itchy skin. It is an early-onset, lifelong condition, often being seen from around 6 months of age and cannot be cured; it can only be managed.

The genetics of CDA Dr Joanna Ilska (KC Genetics Health Manager) was the second speaker at the webinar and she discussed the research evidence and genetics of CDA. While the gene variants for dilution are now known and can be identified with DNA tests, the gene (or genes) that cause CDA have not been found, to date. Joanna explained that, while dilute colour is a predisposing factor for CDA in Dachshunds, the 2 traits are not irrevocably linked. The fact that dilute colours in some other breeds do not suffer from CDA and not all blue or isabella Dachshunds do either, shows this is not a simple genetic condition. The evidence also does not support the view that other health conditions are caused by the coat colour. So, the fact that many of the dilute dogs in our 2021 survey also suffered from autoimmune conditions is more likely to be a result of close inbreeding, use of popular sires, and strong selection within a narrow population pool.

The scientific evidence on the association between colour dilution and CDA was reviewed by the veterinary and genetics specialists on the KC’s Genetics & Health Screening Dog Health Group and they recommended an educational approach rather than a ban on registration of dilute Dachshunds. This webinar was part of that educational approach.

Recognising that where there is demand, there will be supply, Joanna stressed the dangers of breeding for “rare” colours and offered some practical advice to minimise the risks. This included carrying out all recommended health screening, breeding from dogs over the age of 2 once they were known to be unaffected by CDA, and avoiding close inbreeding and popular sires.