Foal Immunodeficiency Syndrome (FIS) is a fatal inherited disorder that was first described in Fell Ponies back in 1996. Foals with FIS are normal at birth, but within a few weeks develop severe anaemia. They almost completely lack B-cells, which are a critical part of the immune system. Foals with FIS are euthenased, or die from the effects of opportunistic infections.
After the first report, it became increasingly clear that foals with FIS were being born in the Fell Pony and Dale Pony breeds.
The gene responsible for FIS was identified in 2009. FIS is a recessive disorder, which means that both parents must be FIS carriers for an affected foal to be born. Once a genetic test was available, the advice for breeders in affected breeds was to avoid crossing two FIS carriers. If a horse was tested as a carrier, it should only be mated with horses that had tested clear of FIS.
Fell Pony and Dale Pony breeders did a great job of acting on this advice. The rate of FIS foals being born in Fell Ponies fell almost immediately from around 8% to a single affected foal being born 2012.
Fell Pony and Dale Pony breeders don’t exclude FIS carrier horses from their breeding population. That would be very damaging for the gene pool of these small breeds. Instead, they take advantage of the positive attributes of bloodlines with carriers and simply use genetic testing to avoid producing affected foals. This benefits breeders financially and improves horse welfare, because breeding a foal is expensive and fewer foals are lost.
The FIS gene is also present in Gypsy Cobs, though it is much rarer than in Fell Ponies or Dale Ponies. Testing for FIS is included in our Gypsy health & colour panel. A very small number of Gypsy Cob FIS carriers have been identified in Australia. Our advice for Gypsy cob breeders is exactly the same as the advice for Fell Pony and Dale Pony breeders: if a horse is a carrier, it should only be mated with horses that have tested clear of FIS. Following this advice means you will never lose a foal to FIS, and you can still enjoy all the positive attributes of your beautiful horse.
You can test individually for FIS or as part of the Gypsy health & colour panel. There is a one off sample-processing fee of $40 per horse and the individual test is $14 (Order the FIS test here)or the panel is $120 (Order the Gypsy Colour & Health panel here).