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Immunology: immunodeficiency – Fell pony syndrome
Introduction
- Cause: autosomal recessive inheritance; genetic defect resulting in a mutation in the sodium/myo-inositol cotransporter gene (SLC5A3) on chromosome 26 → immunodeficiency.
- Signs: foals <2 months old; insidious onset lethargy, weight loss, opportunistic infections; anemia; diarrhea, nasal discharge and cough are common.
- Diagnosis: clinical pathology.
- Treatment: supportive only.
- Prognosis: hopeless.
Presenting signs
- Very young foal - foals initially presented at 2-6 weeks. Treated foals may be up to 12-14 weeks old before succumbing.
- Lethargy
. - Weight loss
. - Failure to thrive (poor growth) .
- Fungal infection of mouth with diphtheritic tongue surface
. - Profound anemia
. - Multiple system, opportunistic infections.
Geographic incidence
- Worldwide in Fell ponies Fell Pony .
- Most cases are centered on major breeding regions of Cumbria, UK.
- Case also reported in a Dales pony Dales Pony .
Age predisposition
- 2-3 weeks at first presentation but signs are insidious and probably start around birth.
Breed/Species predisposition
- Fell pony Fell Pony .
Cost considerations
- Treatment of opportunistic infections and supportive therapy until death or euthanasia.
- Mortality rates in some herds up to 25%.
Pathogenesis
Etiology
- Single point mutation on chromosome 26 resulting in a mutation in the sodium/myo-inositol contransporter gene (SLC5A3).
- Inherited as recessive mutation.
Predisposing factors
General- Dam or sire with history of producing affected offspring.
Specific
- Breed.
Pathophysiology
- Suspected bone marrow stem cell anomaly → :
- Immunodeficiency → opportunistic infections.
- Anemia.
- Thymic/lymphoid hypoplasia.
Timecourse
- 8-10 weeks maximum.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Carter S D, Fox-Clipsham L Y, Christley R & Swinburne J (2013) Foal immunodeficiency syndrome: carrier testing has markedly reduced disease incidence. Vet Rec 172 (15), 398 PubMed.
- Tallmadge R L et al (2012) Fell pony syndrome: characterisation of developmental hematopoesis failur eand associated gene expression profiles. Clin Vaccine Immunol 19 (7), 1054-1064 PubMed.
- Fox-Clipsham L Y et al (2011) Identification of a mutation associated with fatal Foal Immunodeficiency Syndrome in the Fell and Dales pony. PLoS Gent 7 (7), e1002133 PubMed.
- Fox-Clipsham L Y, Brown E E, Carter S D & Swinburne J E (2011) Population screening of endangered horse breeds for the foal immunodeficiency syndrome mutation. Vet Rec 169 (25), 655 PubMed.
- Fox-Clipsham L et al (2009) Immunodeficiency/anaemia syndrome in a Dales pony. Vet Rec 165 (10), 289-290 PubMed.
- Gardner R B, Hart K A, Stokol T, Divers T J & Flaminio J B F (2006) Fell Pony Syndrome in a pony in North America. J Vet Intern Med 20 (1), 198-203 PubMed.
- Thomas G W, Bell S C & Carter S D (2005) Immunoglobulin and peripheral B-lymphocyte concentrations in Fell pony foal syndrome. Equine Vet J 37 (1), 48-52 PubMed.
- Thomas G W, Bell S C, Phythian C et al (2003) Aid to the antemortem diagnosis of Fell pony foal syndrome by the analysis of B lymphocytes. Vet Rec 152 (20), 618-621 PubMed.
- Dixon J B et al (2000) Discriminant and multiple regression anelysis of anemia and opportunistic infection in Fell Pony foals. Vet Clin Pathol 29, 84-86 PubMed.
- Perryman L E (2000) Primary immunodeficiencies of horses. Vet Clin North Am Equine Pract 16(1), 105-116 PubMed.
- Richards A J M et al (2000) Anemia, diarrhea and opportunistic infections in Fell Ponies. Equine Vet J 32, 386-391 PubMed.
- Young K M & Lunn D P (2000) Immunodiagnostic testing in horses. Vet Clin North Am Equine Pract 16 (1), 79-103 PubMed.
- Scholes S F E et al (1998) A syndrome of anemia, immunodeficiency and peripheral ganglionopathy in Fell pony foals. Vet Rec 142, 128-134 PubMed.
Other sources of information
- Knottenbelt D C (1999) Fell pony syndrome. In: Proc 38th BEVA Congress. pp 71-72.