Giselbrecht Juliana, Nell Barbara
Department of Companion Animals and Horses, University of Veterinary Medicine, 1210 Vienna, Austria.
Animals (Basel). 2025 Aug 11;15(16):2342. doi: 10.3390/ani15162342.
This case report investigated the cause of visual impairment at night in Beagle dogs in a family of 12 individuals. Four related adult male Beagles with impaired night vision and eight related Beagles (three females, five males) underwent a complete ophthalmological examination at the ophthalmology service. Electroretinography was performed on four dogs with impaired night vision after dark adaptation to evaluate retinal function. Retinoscopy was performed in 12 dogs in a standing or sitting position to assess refraction. Axial globe measurements were conducted using B-scan ultrasonography in nine dogs. In total, twelve adult Beagles (nine males, three females) from four generations were evaluated, with nine dogs showing impaired night vision. Ophthalmic examinations revealed no abnormalities that could explain the visual impairment. Electroretinography showed normal retinal function. In total, 83.3% (10/12) of the dogs were myopic, with refractive errors ranging from -1.25 to -6.25 diopters (D). All dogs with night vision impairment were significantly more myopic (median: -4.88 D) than those without impairment (median: -1.25 D). In two myopic dogs, the insertion of contact lenses improved navigation in the dark maze test. Myopic dogs showed a significantly greater vitreous body depth (10.1 mm; range 9.7-10.3 mm) compared to emmetropic dogs (9.5 mm; range: 9.4-9.6 mm). These findings suggest that in dogs with night vision impairment, retinoscopy should be included in the ophthalmological exam to exclude myopia as a potential cause. Further research is needed to determine the cause of myopia in the tested Beagles and to investigate possible genetic factors.
本病例报告调查了一个有12只比格犬的家族中比格犬夜间视力受损的原因。4只患有夜间视力受损的成年雄性比格犬和8只相关比格犬（3只雌性，5只雄性）在眼科接受了全面的眼科检查。对4只夜间视力受损的犬在暗适应后进行视网膜电图检查以评估视网膜功能。对12只站立或坐姿的犬进行检影验光以评估屈光状态。使用B超超声检查对9只犬进行眼球轴长测量。总共评估了来自四代的12只成年比格犬（9只雄性，3只雌性），其中9只犬表现出夜间视力受损。眼科检查未发现可解释视力受损的异常情况。视网膜电图显示视网膜功能正常。总共83.3%（10/12）的犬为近视，屈光不正范围为-1.25至-6.25屈光度（D）。所有夜间视力受损的犬比未受损的犬近视程度明显更高（中位数：-4.88 D）（中位数：-1.25 D）。在两只近视犬中，佩戴隐形眼镜改善了它们在黑暗迷宫测试中的导航能力。与正视犬（9.5 mm；范围：9.4 - 9.6 mm）相比，近视犬的玻璃体深度明显更大（10.1 mm；范围9.7 - 10.3 mm）。这些发现表明，对于夜间视力受损的犬，眼科检查应包括检影验光以排除近视作为潜在原因。需要进一步研究以确定受试比格犬近视的原因并调查可能的遗传因素。
