This one is for breeders producing pure and part-bred Gypsy horses, Fell Ponies and Dale Ponies: we now have FIS testing.
Foal Immunodeficiency Syndrome (FIS) used to be called Fell Pony syndrome. It is a fatal inherited disorder that has been found in pure and part-bred Fell Ponies, Dale Ponies and Gypsy breeds. Foals with FIS are normal at birth, but within a few weeks develop severe anaemia and B-lymphopenia. If they are not euthenased they will die from the effects of opportunistic infections.
FIS is an autosomal recessive disorder. Autosomal disorders are equally likely to affect male or female horses, while “recessive” means that a horse needs to inherit the FIS mutation from both its sire and its dam to be affected. Horses that have inherited the FIS mutation from just one parent are called FIS carriers, and do not have physical signs of this disorder.
In a group of Gypsy horses in the USA, about 9% were found to be carriers. The proportion of FIS carriers is higher in Fell Ponies, but breeders are using the test very well to avoid producing affected foals.
