|Sixty-two Bernese Mountain Dogs (38 males and 24 females), whose ages ranged from 2 months to 9 years, were examined over a period of 3 years.
Visual behavior, pupillary light reflexes, menace responses and ocular fundi were evaluated in all animals. Electroretinography (ERG) was performed on six of the affected dogs after dark adaptation. Fluorescein angiography (FA) was performed on one affected dog. Whenever possible, the pedigrees of the affected dogs were evaluated.
A histological examination of the retina was performed on one of the affected dogs.
Eight dogs (seven males and one female) were diagnosed with retinopathy with an early onset of clinical signs. (Four dogs were aged between 3 months and 1 year, two dogs were aged 2 and 3.5 years, and one dog was 7 years old.)
Night vision was impaired in most of the dogs.
Retinopathy was characterized ophthalmoscopically by a bilateral, symmetrical horizontal zone of tapetal hyper-reflectivity adjacent to and above the optic disc, and sometimes by peri-papillary hyper-reflectivity. ERG changes included a reduction in b-wave amplitude varying from one case to another. Fluoroscein angiography demonstrated an ischemic-type alteration with epitheliopathy opposite the hyper-reflective zone.
Pedigree examinations suggested a familial predisposition.
The histological examination indicated photoreceptor degeneration that was more pronounced in the central tapetal zone. In France, retinopathy in the Bernese Mountain Dog involves an early retinal degeneration that produces specific manifestations of the ocular fundus, night visual impairment or blindness, and has familial transmission.
Source: Chaudieu, G. & Molon-Noblot, S. (2004):
Early retinopathy in the Bernese Mountain Dog in France: preliminary observations. In: Veterinary Ophthalmology 7 (3), 175-184.
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