Progressive visual loss and severe retinal degeneration in a captive Kodiak bear ( Ursus arctos mittendorfi)

• Published in: Veterinary Record Case Reports
• Main Authors: Caruso, Kelly A, Koch, Seth, Reynolds, Benjamin David, McCarthy, Paul Massimo Giannoni, Whittaker, Cameron J
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2020
• Subjects: Ursus arctos
• Online Access: http://dx.doi.org/10.1136/vetreccr-2020-001115; https://onlinelibrary.wiley.com/doi/pdf/10.1136/vetreccr-2020-001115; https://onlinelibrary.wiley.com/doi/full-xml/10.1136/vetreccr-2020-001115

SUMMARY A 27‐year‐old female Kodiak bear displayed signs of progressive visual loss over an 18‐year period. The bear was examined under general anaesthesia, where fixed mydriatic pupils, a diffusely hyper‐reflective retina with vascular attenuation was observed. An electroretinogram was performed bilaterally, revealing no electrical activity associated with either retina and confirming a diagnosis of severe bilateral retinal degeneration. The bear was euthanased eight months later due to a diagnosis of a metastasised hepatic neoplasm. Histopathology of the bear's eyes revealed marked outer layer retinal degeneration. The aetiology of this retinal degeneration could not be confirmed.