Congenital Cerebellar Ataxia in the Gotland Pony Breed

Abstract

Summary A probably hereditary cerebellar ataxia in the Swedish Gotland pony breed is described. Its frequency was estimated to be 1—1.5 per cent. The ataxia follows, as a rule, the normal instability of movements after birth, but it can also appear later in life. The pattern of abnormal movements was rather uniform with an unstable, stiff gait, the legs wide apart, and very straight hocks. The forelegs were lifted high up, with superflexion of the upper joints. The foals were very likely to fall, especially when trying to jump. The cerebellum weighed less than normal. The lobular and foliar structure was much accentuated. As a consequence of the relatively high degree of inbreeding it was difficult to evaluate the theory of a genetic etiology. There were, however, good arguments for a recessive, autosomal gene forming the basis and carried by the Olle‐line. Based on a defect frequency of 0.015 the frequency of the defect gene should be about 0.12. The penetrance might very well be 1 or close to 1. Zusammenfassung Kongenitale cerebrale Ataxie beim Gotland‐Pony Es wird eine wahrscheinlich vererbliche cerebellare Ataxie beim schwedischen Gotland‐Pony beschrieben, die mit einer Häufigkeit von 1—1 1/2% auftritt. Die Ataxie folgt den normalen unsicheren Bewegungen des Neugeborenen; sie kann aber auch später in Erscheinung treten. Die Krankheit äußert sich meistens durch einen unsicheren, steifen, breitbeinigen Gang mit gestreckten Sprunggelenken. Die Vorderbeine werden mit einer übertriebenen Beugung der oberen Gelenke hoch angehoben. Die Fohlen fallen bei Springversuchen leicht hin. Das Gewicht des Kleinhirns war bei den betroffenen Tieren gegenüber der Norm verringert. Auffallend war die ausgeprägte Ausbildung der lappigen und faltigen Struktur des Cerebellums. Der relativ hohe Inzuchtgrad dieser Ponies erschwert die Deutung einer genetischen ätiologie dieses Leidens. Doch gibt es gute Anhaltspunkte dafür, daß ein rezessives autosomales Gen, das von der Olle‐Linie in die Gotlandzucht gebracht wurde, Ursache dieser Erbkrankheit ist. Basiert auf einer Defektfrequenz von 0,015 dürfte die Frequenz des defekten Gens etwa 0,12 betragen. Die Penetranz dieses Gens kann gut 1 oder angenähert 1 betragen. Résumé Ataxie cérébelleuse congénitale chez le poney du Gotland On décrit une ataxie cérébelleuse probablement héréditaire chez le poney du Gotland suédois, qui se manifeste à une fréquence de 1—1,5%. En règle générale, l'ataxie succède à l'instabilité normale des mouvements du nouveau‐né, mais elle peut également se manifester plus tard. La maladie se caractérise par une démarche instable et raide, les jambes sont largement écartées et les jarrets tendus. L'animal lève les jambes avant avec une flexion exagérée des articulations supérieures. Les poulains vacillent, surtout lorsqu'ils essaient de sauter. Le poids du cervelet est en‐dessous de la normale. Sa structure lobulaire et ses replis sont accentués. Le degré relativement élevé de consanguinité de ces poneys rend difficile une estimation de l'étiologie génétique de la ma...

Cerebellar Purkinje cell degeneration in a mule foal (Equus mulus mulus)

“…The mare was a mixed breed pony and the stallion was a mixed breed donkey. In ponies, PCD has been reported in the Gotland pony breed with a suspected recessive mode on inheritance 5. Although the phenotype of the mare was not consistent with this breed, it was not possible to confirm her origin.…”

“…Purkinje cell degeneration (PCD), also known as cerebellar cortical abiotrophy (CCA), is a neurological condition characterised by a premature degeneration of the Purkinje cell population in the cerebellum 2 3. PCD has been reported in dogs, cattle, cats, horses, ponies, sheep, pigs and chickens 3–9. Among these species, there are certainly differences in the time of onset, severity of clinical signs and histological lesions, suggesting a spectrum of different disease mechanisms 3…”

“…In horses, PCD is found almost exclusively in the Arabian breed and partbred Arabian horses 4 10–12. A few additional cases have been reported affecting the Gotland pony breed,5 Oldenburg warmblood horses13 and American miniature horses 14…”

Cerebellar abiotrophy in an Icelandic horse

“…This mutation has been transmitted to the Trakehner, Welsh pony and Bashkir Curly horse breeds due to cross breeding [ 7 ]. Cerebellar abiotrophy has also been reported in a number of other breeds such as the New Caledonia horse [ 8 ], Oldenburg [ 9 ], American Miniature Horse [ 10 ] and the Gotland pony [ 11 ].…”

Morphometric magnetic resonance imaging and genetic testing in cerebellar abiotrophy in Arabian horses

“…CA is found in Arabians and partbred Arabian horses but it has also been reported in the Gotland pony and the Oldenburg Warmblood horse [2,3]. CA is seen in several species including dogs, sheep and cattle, but it is likely that in these species, CA does not have the same aetiology as in the horse [1,4,5].…”