HYPERKERATOSIS

As we all know, the Irish Terrier basically is a sound and healthy breed. Despite its small population and rather small genetic pool.  The main health issue that we have been dealing with over recent years is Digital Hyperkeratosis (CF) now termed Hereditary Footpad Hyperkeratosis (HFH). " It's always been in the breed", the breeders used to say in the old days, shrugging their shoulders.  But modern researchers being convinced that a disease of genetic origin must not be accepted as a sword of Damocles, as fate, decided to find out the way of inheritance to keep the breed healthy and to make it even healthier again.  The CF - riddle has been solved quite recently by Prof. Dr Toss Leeb (University of Bern Switzerland). The marker gene has been identified!

Designated 'HFH-A' the recessive marker gene is a variant of the FAM83G gene.  The condition is usually first seen by owners at 4-5 months of age and involves all footpads.  With time horny protrusions appear on the rims of the footpads and the pad surface becomes hard and develops cracks.  Affected animals avoid walking on irregular surfaces and may go lame.  The nails of affected dogs are very hard and seem to grow faster.  Visual diagnosis is not always simple as the intensity of clinical symptoms can vary between animals or even between pads on the same animal, therefore the DNA test is the conclusive diagnosis.  Inspections should be careful not to mistake for HFH accidental cuts or splits or abrasions, such as those from exercise on hard surfaces.

The result of the research was published in spring 2014 and the genetic test became available after evaluating its reliability and technical feasibility.  This is a wonderful contribution for all health concerned breeders as the test now allows us to find out about the genetic disposition of our breeding stock and especially about potential carriers, those dogs which are so risky in breeding as they do not show any sign of the disease but, when bred to a carrier partner, may produce affected offspring.  Swiss researcher, Prof. Dr Tosso Leeb, having managed to find the gene marker in the Kromfohrlander breed, directly went on with his research on the Irish Terrier.  

In 2008 the French group (Antagene and Rennes University) started on a different background: after having identified the gene marker for a similar condition in the Dogue de Bordeaux, Dr Anne Thomas was interested in doing the same research for the Irish Terrier breed and attend a show in Lyon with the aim of collecting samples from those Irish Terriers shown at that show.  There she met the French breeder Frederique Andersson who immediately agreed to collecting samples from all over France. 

Due to personal relations this idea spread to Germany where Andrea Gasch and Helga Richter were asked by Antagene to collect samples and then spread to Britain where Susan Seabridge spent a tremendous amount of time and energy in collecting samples and biopsies.  In Lactea it was Tatiana Necajeva who as well as in her country helped find in Russia several affected dogs based on well-known Western European lines.  The French research therefore focused exclusively on contemporary dogs.  Early November 2013, Anne Thomas presented the Antagene work at the German breeders’ annual reunion informing them that they had not yet reached a conclusion.  At this time neither Leeb or Thomas knew that both scientist groups were working on the same subject which Professor. Dr Leeb was able to report the successful conclusion and, being advised of their interest, invited the Antigen group to collaborate with him for the final evaluation.

Antagene were able to carry this work forward and offer testing to identify those Irish Terriers that are designated: 'Affected', 'Carries', or 'Clear' of HFH. their services can be found on http://www.antagene.com.  There are no restrictions on testing based on Prof Leeb's research.  The UK Laboratory, Animal DNA Diagnostics offers testing from simple at home cheek swabs (including puppies) and have collected samples from UK dogs of known status to validate their testing.  Details available on https://www.animaldadiagnostics.co.uk.

Now that the generic state of dogs can identify correctly, all dogs can be retained for breeding if they are desirable breeding stock. Mating combinations can be decided which avoid the risk of producing Foot Hyperkeratosis affected pups. The different breeding combinations and their outcomes are listed below. The combinations in BOLD risk affected pups and should be avoided, but there are recommended combinations which include both carriers and indeed affected dogs (in fact the affected - clear combination has the advantages that the resulting pups do not need to be genetically tested as they will be carriers).  Breeding from an affected dog could therefore be contemplated if he was an exceptional dog in other ways.  

Obviously, the LONG-TERM aim is to gradually remove the carriers from the breeding group, but this does diminish and the breeding group, so in an ideal world would be undertaken very gradually. Unfortunately, often breeders are too eager to discard carriers from breeding!    

The following table makes it easy if you don't understand has been provided by Dr June Swinburne, Animal DNA Diagnostics.   

Affective X Affected = 100 % Affected

Affected X Carrier = 50% Affected / 50 % Carrier

Affected X Clear = 100% Carrier

Carrier X Carrier = 25% Affective, 25 % Clear, 50 % Carrier

Carrier X Clear = 50% Carrier, 50% Clear

Clear X Clear = 100% Clear