title: Novel retinopathy in related Gordon setters: a clinical, behavioral, electrophysiological, and genetic investigation.
abstract: OBJECTIVE
  To conduct ophthalmic, behavioral, electrophysiological, and genetic testing on two related Gordon setters presented for day blindness and compare findings with those of nine related and unrelated Gordon setters.
  
  
  METHODS
  All dogs underwent comprehensive ophthalmic examination. Maze testing was conducted under different light intensities. Rod and cone function was assessed electroretinographically. DNA samples were screened for five canine retinal disease gene mutations.
  
  
  RESULTS
  Ophthalmic examination was unremarkable in all dogs. There was no notable difference between day blind dogs and the reference population in scotopic and mesopic maze tests. Day blind dogs performed worse in the photopic maze with slower course completion time and more obstacle collisions. Electroretinography revealed extinguished cone function in day blind dogs and depressed rod responses in all but two reference dogs. One reference population dog presented with day blindness 1 year after initial examination. Mutations that cause achromatopsia (in CNGB3) and cone-rod dystrophies (in ADAM9 and IQCB1) were not detected in any dog tested, although five reference dogs were carriers of the mutation in C2orf71 that causes rod-cone degeneration 4 (rcd4) in Gordon setters and in polski owczarek nizinny dogs.
  
  
  CONCLUSIONS
  This report describes a novel retinopathy in related Gordon setters that has clinical signs and vision testing results consistent with achromatopsia but electroretinographic results suggestive of cone-rod dystrophy. The majority of Gordon setters in this study had low rod responses on electroretinography but it is unclear whether this was indicative of rod dysfunction or normal for the breed. Longer-term observation of affected individuals is warranted.
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA. kgkoehler@ucdavis.edu.
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Good
authors.affiliation: Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.|Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, 48824, USA.
authors.forename: András M
authors.identifier: http://orcid.org/0000-0002-8845-0588
authors.initials: AM
authors.lastname: Komáromy
authors.affiliation: Department of Population Health and Reproduction, School of Veterinary Medicine, University of California- Davis, Davis, CA, 95616, USA.
authors.forename: Philip H
authors.initials: PH
authors.lastname: Kass
authors.affiliation: Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Rehovot, 7610001, Israel.
authors.forename: Ron
authors.initials: R
authors.lastname: Ofri
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D003117:Color Vision Defects / Q000235:genetics / Q000503:physiopathology* / Q000662:veterinary*; D004283:Dog Diseases / Q000235:genetics* / Q000503:physiopathology*; D004285:Dogs; D004596:Electroretinography / Q000662:veterinary; D010375:Pedigree; D012164:Retinal Diseases / Q000235:genetics / Q000503:physiopathology / Q000662:veterinary*; D012174:Retinitis Pigmentosa / Q000235:genetics / Q000503:physiopathology / Q000662:veterinary; D013045:Species Specificity
keywords: achromatopsia; cone-rod dystrophy; day blindness; dog; electroretinography; night blindness