Ancient British Breed at Risk
The Horse Trust is funding a three-year project to develop a genetic diagnostic test for Fell Pony Syndrome (FPS) and thus enable control and possible elimination of the disease.
The work will be
undertaken at the Animal Health Trust, Newmarket, and the University of
Liverpool Veterinary School.
The Fell pony, an
ancient British pony breed categorised as “at risk” by the Rare Breeds
Survival Trust, has over the past decade or so been subject to a severe
immune deficiency known as Fell Pony Syndrome (FPS), which results in
the death of some of the newborn foals.
Foals
affected with FPS appear normal at birth but within a few weeks begin
to lose condition and suffer diarrhoea, coughing and weight loss.
Severe anaemia and immune dysfunction follows, leading to wasting and
finally death. The disease is always fatal.
As a
large percentage of these ponies live and breed on the fell, the
prevalence of FPS is unclear. Despite an improvement in foal
registration numbers in recent years, Fell Pony Syndrome remains of
concern to breeders.
Studbook analysis and knowledge
of affected foals strongly suggests that this is an inherited disease
caused by an autosomal recessive genetic mutation. A DNA based test for
this mutation would enable carriers of FPS to be identified and the
conception of affected foals prevented.
As well as
identifying carriers in the Fell pony population, the project will be
used to identify any carriers in other breeds which have been involved
in the extensive outbreeding of Fell ponies over the
years.
“The success of this project will prevent the
suffering of newborn Fell pony foals affected with FPS,” says project
leader Dr June Swinburne, senior post-doctoral equine molecular
geneticist at the Animal Health Trust Centre for Preventive Medicine.
“Foals affected by the condition inherit an incurable genetic defect
which results in severe wasting and a profound anaemia together with
multiple infections. Veterinary intervention is in vain and once the
condition is diagnosed foals are often euthanased. The gradual but
relentless decline in these foals leaves both veterinary surgeons and
breeders powerless.
“Breeders are supportive of our
attempt to develop a diagnostic test which will help to prevent
carrier-carrier matings, one in four of which results in an affected
foal.”
The Horse Trust’s Chief Executive and
resident veterinary surgeon Paul Jepson said: “This is an exciting and
achievable project with significant benefits for equine health and
welfare, as it will lead to the prevention and elimination of a fatal
disease.”
The
History of FPS
The extent of FPS in the
population may have resulted from the recent history of the breed, as
there was a dramatic fall in numbers after the Second World War, which
would have resulted in a ‘genetic bottleneck’. The small number of
animals which were subsequently used to invigorate the breed would have
made it much more likely that inherited diseases would appear in
successive generations. FPS may therefore be a direct result of the
genetic bottleneck. The situation may have been exacerbated by the
unknowing over-use of one or several stallions which were carriers of
the condition. This condition is a serious clinical problem which at
the moment is restricted to the Fell pony population but which could
spread to other breeds at any time. Indeed it may be possible that
carriers of the condition already exist in other breeds which have
interbred with the Fell pony over many years.
The
Fell pony breed is not a closed population; it is known that the Dales
pony and others are interbred with the Fell, putting their populations
at risk by the spread of FPS. The Dales pony is categorised as
“critical” (the highest level) by the RBST, so it is imperative that
the spread of FPS is halted. Other breeds will be randomly tested to
detect any further penetration of the defect into the equine
population.
