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Mammals (other)
Progressive visual loss and severe retinal degeneration in a captive Kodiak bear (Ursus arctos mittendorfi)
  1. Kelly A Caruso1,
  2. Seth Koch2,
  3. Benjamin David Reynolds1,
  4. Paul Massimo Giannoni McCarthy1 and
  5. Cameron J Whittaker1
  1. 1Eye Clinic for Animals, Sydney, New South Wales, Australia
  2. 2Department of Ophthalmology, Hickory Veterinary Hospital, Plymouth Meeting, Pennsylvania, USA
  1. Correspondence to Dr Paul Massimo Giannoni McCarthy; paul.m.giannoni{at}


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.

  • retinopathy
  • ursid
  • kodiak bear
  • retinal degeneration
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  • Contributors KAC: drafting and final approval of the version published. SK and CJW: critical revision and final approval of the version published. BDR and PMGM: drafting and critical revision.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement There are no data in this work.

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