Foal Immunodeficiency Syndrome (FIS)

Foal Immunodeficiency Syndrome

Turnaround: 3-5 business daysTurnaround: 7-10 business days

Price: $45.00Price: £35.00

Breeds: Canadian, Clydesdale, Clydesdale Cross, Clydesdale/Cob, Cob Cross, Cob/Thoroughbred, Cob/Warmblood, Dales Pony, Drum Horse, Fell Pony, Gypsy Cob, Gypsy Cob/Clydesdale, Gypsy Drum Horse, Gypsy Horse, Gypsy Vanner, Irish Cob, Mixed Breed, Tinker Horse, Traditional Gypsy Cob, Unspecified, Welsh Cob


Foal Immunodeficiency Syndrome (FIS) is a recessive genetic disease that primarily affects two relatively rare native UK pony breeds: the Dales and Fell pony. FIS is caused by a single mutation in the sodium transporter gene (SLC5A3). This gene plays a vital role in the regulatory response of many tissues, including the lymphoid tissues.

As many as 10% of all Fell ponies born every year are born with FIS. This has put a strain on the long-term survival of this breed. This also increases the chance of FIS spreading into other breeds’ genomes. Animal Genetics Inc. has found the mutation that causes FIS in approximately 9% of Gypsy horse breeds in the US and Europe, allowing us to test for FIS.

Because FIS is a recessive disease, foals must have two copies of the mutated gene in order to be affected with FIS. Therefore, each parent must be a carrier of the mutated gene in order to have an affected foal. A carrier has only one copy of the mutated gene and does not present symptoms. 

Affected foals appear healthy and normal at birth, but begin to show signs of weakness, a dull coat and anorexia around 2-3 weeks after birth. The first clinical signs of this disease include diarrhea, nasal discharge, poor growth, pale gums and decreased appetite. Vision may be affected, presumably due to secondary bacterial infections. Mortality rate for foals affected by FIS is 100%, despite intensive treatment. All FIS affected foals generally die or are euthanized before they reach the age of 3 months.

FIS is an autosomal recessive trait, meaning a foal can only be affected if the foal inherits the disease from both parents. Parents that are carriers do not have any symptoms associated with FIS. If two carriers are bred with one another, there is a 25% chance per foal born that they will develop symptoms of FIS. There is a 50% chance per foal born that they will also become carriers of the disease.

Animal Genetics offers DNA testing for both the FIS mutation found in Dale and Fell Ponies as well as any horses with Dale and Fell Pony blood lines.

Possible Results

Genotype Description
FIS/FIS Affected: Horse has two copies of the gene mutation associated with FIS and will exhibit symptoms of the disorder.
N/FIS Carrier: Horse has one copy of the gene mutation associated with FIS. Horse has a chance to pass this gene on to any offspring.
N/N Clear: Horse is negative for the gene mutation associated with FIS.
NR/NR No Result- Please submit a new sample for this animal.