Sunday, 15 April 2012

Good news, bad news and interesting news

Good news update: blood samples from a further five HWSS affected ponies have been processed by the Bannasch Laboratory.  The analysis from these arrays is not yet complete, however early indications are that the areas of significance on the genome will be greatly reduced.  Instead of having a 'scattershot' approach to the molecular search, the specific area/s of interest are now being pinpointed.  This work cannot be hurried; we all need to await the outcome with grace and patience.

Bad news update: not the type one ever wishes to report.  The group has been notified that two HWSS affected fillies have recently been euthanased; both were profound cases of  HWSS.  These fillies were euthanased on humane grounds after advice from the owner's veterinarian and farrier.  The fillies had both been under the care of the care of these professionals since they were 3 months old.   

The veterinarian (under request from the owner) performed a post-mortem on both ponies.  This report, plus various body tissue samples and the legs from each pony were sent to the Centre for Equine Health at UC Davis for in-depth analysis.  
Let us hope that the lives of these two fillies will not have been in vain and that through the generosity of their owner in sending samples and body parts for pathology, will help successive generations of the breed.  The condolences of the research group members go out to this owner on the loss of these ponies.

Interesting news update.  This is interesting news from the academic and research perspective but probably will be seen more as a bad news post for the Connemara pony community at large.

Notification to the research group of the first clinical case of HWSS, has just this week, come in from yet another new, country.  The research group was already aware that HWSS was in this genepool but only because of the ponies which have been exported from this location that have gone on to produce HWSS offspring in other countries.   

For example, to date the only clinical case of HWSS in New Zealand is in a imported in utero from this country but, born in New Zealand, pony.  To say the least, this was a surprise to all at the time.  It also has to be noted that this in-foal mare was imported to New Zealand well before existance of the HWSS condition was being acknowledged in the wider Connemara pony population. 

What is extremely interesting from the pedigree research perspective is that in each of these  ponies from this new country, looking at their four generation pedigrees they have nothing in common with each other.  It is only when one is able to look at extended pedigrees that the probable lines of descent become apparant.  

The hypothesis behind the transmission of HWSS, as you are now all well aware, is that it is a simple recessive progression; it can pass through many generations without it ever being expressed.  To date there are (to the members of the research group) well known and obvious patterns of inheritance which appear in affected HWSS ponies.  For the most part these are 'close-up' in the pedigrees of affected ponies and quite obvious within a 4 generation pedigree.  However with two of the 'new' carriers and the one recently notified HWSS affected pony, the already known lines of descent do not appear until  6-7 generations back in the pedigrees.  

This indicates that HWSS came into this 'new'  country  with the early imports of the 1960's and 1970's and that the condition was already widely spread within the Connemara populations from Ireland and the UK.  
With the contraction of the genepool towards a more homozygous state (as is happening with the Connemara breed worldwide) then statistically one expects to see a rise in HWSS affected ponies in this particular country.

Other news: Blood samples from clinically affected HWSS ponies have recently been sent to the Bannasch laboratory from Denmark, Germany and Sweden.  Thank you to the pony owners who at their own expense had their ponies inspected, identified and blood sampled by a veterinary professional, provided the high definition photographs of the hooves and then also paid the shipping costs to the Bannasch Laboratory, UC Davis.   Sending biological samples between countries is a very involved, precise and expensive process.  Thank you to those people.

New Zealand breeders have sent over a consignment of  blood and hair samples from 39 ponies.  This shipment included the one HWSS case, the dam of this case and a normal half sibling.   

New Zealand is in a very interesting position genetically.  The ponies in this country are for the most part even more closely related to each other than seen elsewhere in the world.  This is the result of geographic isolation and the prohibitive cost of importation.  The genepool still includes breeding stock whose parents were from the first wave of imports into the country in the 1970's.   The large number of blood samples sent from New Zealand is to provide a pool of ponies that are expected to to be free of HWSS carrier status, which can then be used as 'controls' in developing the future diagnostic test.  Only time will tell whether this is in fact a true reflection of the genetic status of the Connemara pony in New Zealand.