Wednesday, 4 July 2012

Genetic Disorders in Arabian Horses

Considerate Breeding.

Investment in horses and in particular breeding of horses is financially and emotionally an expensive venture at the best of times. It should not be entered into lightly without consideration of the possibility of factors out of our control playing havoc with the best laid plans. 

Breeding is a game of juggling genetic possibilities and we endeavour to produce the best foal possible my matching stallions and mares for their physical, mental and proven or potential capabilities to create a horse to meet whatever the breeder’s vision into the future may be.

What of the invisible ingredients in our mix? The genetic codes that actually create our foal, the map that really charts the creation and engineering of everything the horse breeder sets in motion. Mostly we apply our best skills as a judge of those horses in our various fields of expertise and then cross our fingers perhaps confident we do know what the mix will create but praying nature does not have a hidden agenda. Which she does.

Genetics and nature are a fluid part of evolution; essential to the survival of any species is diversity created by selection of genetic codes carrying changes. Sadly not all those genetic changes have a role that meets the needs of the species and some are just outright destructive. These we tag as ‘Genetic Disorders’ and generally thank whatever we believe in that they mostly only manifest occasionally. But even that is just an evasion of facing the truth.

The Hispano-Árabe, while essentially an old established breed dating back hundreds of years (as previously discussed to the days of the Moor invasions of the Iberian Peninsula) is undergoing a breed preservation and regeneration programme which by necessity means the introduction of genetic codes from new sources. 

Specifically the increase of new Arabian blood lines and with the modern world diversification of Arabian ‘types’ a far greater range of genetic phenotype (physical characteristics); all of which in the last 30 years the Spanish Hispano-Árabe Stud Book has taken into consideration in developing its grading and testing of the ‘new’ Pure Bred Hispano-Árabes.

However, there is another implication of the re-introduction of Arabian lines to the Hispano-Árabe  at the genetic level. The Arabian horse carries with it known breed specific genetic disorders which Arabian breeders are alerted to by WAHO: 

The probability of the manifestation of these disorders within Pure Arabian breeding programme is higher than in its partbreds (generally) as the chances are that the carrier partbred horses are less likely to be bred back to other carriers. But the Hispano-Árabe is not a partbred, it is a derivative breed and our F1 (PRE x Arabian) are bred back with other F1 stock and by the very fact that the breed is critically low in number the incidence of manifestation of the transmitted Arabian genetic disorders is as high a probability (if not higher) than in the Pure Arabian.

The decision to test or not for these disorders (where testing is available) and then to breed or not (when tested positive as a carrier) has been left to the integrity of the Arabian horse owner.  So in effect while some breeders elect to endeavour to eliminate genetic disorders from their breed programme, others elect to continue breeding. They consider the odds for now might be in their favour with limited losses of foals from the devastating consequences of these disorders but they ignore the future when their action has resulted in the compromise of all Arabian horses as the number of silent carrier’s increases.

The Hispano-Árabe breed protection programme is barely in the gateway in its development. It would be devastating if the work of the past 30 years to protect this breed was to be shattered for want of a moment’s consideration before breeding. If we view our-selves competent to breed horses then we should have the integrity to think not just of our short term desires but of the long term consequences of our choices and decisions. 

The Spanish Government has taken stock of the implications of the introduction of Arabian breed specific genetic disorders being carried into the Hispano-Árabe breed and accordingly the Ministry on 18 June 2012 amended the Hispano-Árabe Breed Rules to adopt measures to deal with this. Details of these measures will be published as soon as I receive exact copy.

However, there is no reason on earth for Hispano-Árabe horse breeders to not exercise common sense. Check the Arabian horse you intend to breed from. If it is a carrier : Don’t breed! It is in the interests of both the Arabian and the Hispano-Árabe owners to ensure before breeding that the Arabian horse is tested clear of those disorders we have tests for.

These are:
  1. Severe Combined Immunodeficiency Disorder (SCID) (test available)
  2. Cerebellar Abiotrophy (CA) (indirect marker test available)
  3. Lavender Foal Syndrome (LFS) (test available)
  4. Occipital Atlanto-Axial Malformation (OAAM) (test not yet available)
The company that developed the test for SCID at present is playing a greed game and withholding ease of access to the test as they intend patenting it as well as apparently charging high fees!  So at present this test can only be obtained through Vet-Gen and Laboklin : 

The CA and LFS disorder tests are available at most laboratories carrying out equine DNA testing so owners can shop around for best prices and labs they feel suit their needs. Hispano-ÁrabeUK uses Animal Genetics Uk for our DNA testing and this lab apart from being sensible on costs provides a superb service for horse owners. 

A little thought and integrity and there is no reason for the worry that maybe all your hopes and plans for a perfect foal are going to be shattered. A bit of consideration for the future and the integrity to not breed if a test is positive and you will not be the founder of the future destruction of the lines of horses you elected to contaminate. 

Hard truths but better to swallow than to stand beside a foal in distress dying because you crossed your fingers and hoped!