IngentaConnect Phenotypic diagnosis of dwarfism in six Friesian horses

Authors: Back, W.; van der Lugt, J. J.; Nikkels, P.G.J.; van den Belt, A. J. M.; van der Kolk, J. H.; Stout, T.A.E.

Source: Equine Veterinary Journal, Volume 40, Number 3, May 2008 , pp. 282-287(6)

Publisher: Equine Veterinary Journal Ltd.

Abstract:

An extreme form of abnormal development, dwarfism, is common in man and some animals, but has not been officially reported in horses. Within the Friesian horse breed, congenital dwarfism has been recognised for many years, but no detailed report exists on its phenotype. The most salient feature of the dwarf syndrome is the physeal growth retardation in both limbs and ribs. Affected animals have approximately 25% shorter fore- and hindlimbs and approximately 50% reduced bodyweight. Post natal growth is still possible in these animals, albeit at a slower rate: the head and back grow faster than the limbs and ribs leading to the characteristic disproportional growth disturbance. Thus, mature dwarfs exhibit a normal, but a relatively larger head conformation, a broader chest with narrowing at the costochondral junction, a disproportionally long back, abnormally short limbs, hyperextension of the fetlocks and narrow long-toed hooves. Furthermore, a dysplastic metaphysis of the distal metacarpus and metatarsus is radiographically evident. Microscopic analysis of the growth plates at the costochondral junction shows an irregular transition from cartilage to bone, and thickening and disturbed formation of chondrocyte columns, which is similar to findings in osteochondrodysplasia.

Keywords: HORSE; EQUINE; GENETICS; GROWTH PLATE; LONGITUDINAL DEVELOPMENT; OSTEOCHONDRODYSPLASIA

Document Type: Case report

DOI: 10.2746/042516408X278201

The full text electronic article is available for purchase. You will be able to download the full text electronic article after payment.

$38.00 plus tax Refund Policy