title: Progressive retinal atrophy in the Polski Owczarek Nizinny dog: a clinical and genetic study.
abstract: OBJECTIVE
  To describe ophthalmic, functional, structural, and genetical characteristics of progressive retinal atrophy (PRA) in the polski owczarek nizinny (PON) breed of dog.
  Client-owned PON dogs (n = 82) from Sweden.
  
  
  METHODS
  Routine examination for presumed inherited eye disease was performed in all dogs. Bilateral full-field electroretinography (ERG) was performed in 11 affected and 4 control dogs. Eyes from one affected dog were studied with light microscopy. DNA samples from 34 Swedish and 30 PON dogs collected by Michigan State University (MSU) were tested for the mutations causing the rcd4 and prcd forms of PRA.
  
  
  RESULTS
  Sixteen of the eighty-two Swedish dogs were diagnosed with PRA. Slight vascular attenuation, first seen at 4.5 years of age, preceded changes in tapetal reflectivity. The initial ERG changes in affected dogs showed markedly diminished rod responses, while cone responses were barely affected. Eventually, cone responses were also reduced. Retinal morphology showed approximately a 50% reduction of photoreceptor nuclei in the outer nuclear layer. Fourteen of fifteen PRA-affected Swedish dogs and eighteen of twenty of the MSU PRA-affected dogs tested genetically were positive for the rcd4 mutation. All tested dogs were negative for the mutation causing prcd-PRA.
  
  
  CONCLUSIONS
  PRA of PON dogs is a late-onset degenerative disease with slow progression. There is early loss of rod function, while the cone system deteriorates later. The rcd4 mutation in the C2ORF71 gene was associated with the majority of the PRA cases tested. The possibility of additional forms of PRA in the breed cannot be excluded.
authors.affiliation: Blue Star Animal Hospital, Gjutjärnsgatan 4, Gothenburg, 417 07, Sweden.
authors.forename: Marika
authors.initials: M
authors.lastname: Svensson
authors.affiliation: Division of Pharmacology and Toxicology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, SE-750 07, Sweden.
authors.forename: Lena
authors.initials: L
authors.lastname: Olsén
authors.affiliation: Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Road D, 208, East Lansing, MI, USA.|Genetics Program, Michigan State University, East Lansing, MI, 48824, USA.
authors.forename: Paige A
authors.initials: PA
authors.lastname: Winkler
authors.affiliation: Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Road D, 208, East Lansing, MI, USA.|Genetics Program, Michigan State University, East Lansing, MI, 48824, USA.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Petersen-Jones
authors.affiliation: Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Tomas
authors.initials: T
authors.lastname: Bergström
authors.affiliation: Veterinary Eye Clinic, Grupy AK Polnoc 2/u10, Warsaw, 00-713, Poland.
authors.forename: Yacek
authors.initials: Y
authors.lastname: Garncarz
authors.affiliation: College of Veterinary Medicine, 900 East Campus Drive, Columbia, MO, 65211, USA.|Retvet KB, Karlsuddsvägen 14b, Vaxholm, 185 93, Sweden.
authors.forename: Kristina
authors.initials: K
authors.lastname: Narfström
mesh_terms: D000818:Animals; D004283:Dog Diseases / Q000000981:diagnostic imaging / Q000235:genetics*; D004285:Dogs; D004596:Electroretinography / Q000662:veterinary; D005260:Female; D008297:Male; D009154:Mutation; D012164:Retinal Diseases / Q000000981:diagnostic imaging / Q000235:genetics / Q000662:veterinary*; D013045:Species Specificity
keywords: Polski owczarek nizinny dog; electroretinography; genetics; morphology; progressive retinal atrophy; rcd4