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. 2008 Jul;49(7):675-81.

Congenital ocular anomalies in purebred and crossbred Rocky and Kentucky Mountain horses in Canada

Bruce H Grahn  1 , Chantale Pinard, Sheila Archer, Rebecca Bellone, George Forsyth, Lynne S Sandmeyer
Affiliations

Congenital ocular anomalies in purebred and crossbred Rocky and Kentucky Mountain horses in Canada

Bruce H Grahn et al. Can Vet J. 2008 Jul.

Abstract
in English, French

Multiple congenital ocular anomalies in purebred and crossbred Rocky and Kentucky Mountain horses in Canada are frequently diagnosed with biomicroscopic and indirect ophthalmoscopic examination. In order of frequency detected, these include temporal ciliary epithelial cysts; iridal hypoplasia; prominent corneas; focal temporal retinal degeneration related to ciliary cysts; and, rarely, retinal detachment. A pedigree analysis confirms a dominant mode of inheritance with incomplete penetrance and with a linkage to coat color.

Anomalie oculaires congénitales chez des chevaux Rocky et Kentucky Mountain de race pure et croisée au Canada. Des anomalies oculaires congénitales multiples chez des chevaux Rocky et Kentucky Mountain de race pure et croisée au Canada sont souvent diagnostiquées par examens biomicroscopiques et ophtalmoscopiques indirects. Par ordre de fréquence, les anomalies détectées comprennent les kystes épithéliaux ciliaires temporaux, l’hypoplasie iridienne, la cornée proéminente, la dégénération focale de la rétine temporale reliée aux kystes ciliaires et, rarement, le détachement de la rétine. Une analyse du pedigree confirme un mode dominant de transmission génétique avec pénétrance incomplète et liaison à la couleur de la robe.

(Traduit par Docteur André Blouin)

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Figures

Figure 1
Figure 1
The most common lesions in Rocky and Kentucky Mountain horses in Canada were large temporal ciliary cysts. Most were bilateral as noted in this Rocky Mountain filly.
Figure 2
Figure 2
Other common lesions in this study were focal retinal degeneration with curvilinear streaks related to cysts and focal retinal detachment. Complete retinal detachments were uncommon. Note the hyperreflectivity in the temporal fundi of these 2 Rocky Mountain mares and the multiple curvilinear streaks.
Figure 3
Figure 3
Iridal hypoplasia was confirmed by a lack of any substantial dilatation after 1% tropicamide was applied for approximately 30 minutes and by small pupils, encircling hypoplastic granula iridica, and thin irides.
Figure 4
Figure 4
Pedigree of horses affected with Rocky Mountain horse eye anomaly in Canada. Note that cysts were detected in the F1 crossbred generation sired by a Rocky Mountain stallion with cysts (all but 2 dams were gaited breeds). Note also that the F2 generation failed to express ciliary cysts, expressed ciliary cysts alone, expressed ciliary cysts and multiple ocular anomali es, when sired by either a Rocky Mountain stallion with ciliary cysts or a Rocky Mountain stallion with ciliary cysts and multiple ocular anomalies.
Figure 4
Figure 4
Pedigree of horses affected with Rocky Mountain horse eye anomaly in Canada. Note that cysts were detected in the F1 crossbred generation sired by a Rocky Mountain stallion with cysts (all but 2 dams were gaited breeds). Note also that the F2 generation failed to express ciliary cysts, expressed ciliary cysts alone, expressed ciliary cysts and multiple ocular anomali es, when sired by either a Rocky Mountain stallion with ciliary cysts or a Rocky Mountain stallion with ciliary cysts and multiple ocular anomalies.
Figure 5
Figure 5
Pedigree of some of the Kentucky Mountain horses that were related and when examined found to be affected with uveal cysts.
See this image and copyright information in PMC

Comment in

References

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