Pathological and electrophysiological features of a canine cone-rod dystrophy in the miniature longhaired dachshund.
OBJECTIVE
To characterize the electrophysiological and histopathological features of a retinal degenerative disease in a colony of miniature longhaired dachshunds known to have a form of progressive retinal atrophy (PRA).


METHODS
Serial electroretinograms were recorded from affected homozygous (n = 36) and heterozygous (n = 15) dogs. Morphologic investigations including immunohistochemistry and lectin histochemistry were performed on selected homozygous animals (n = 15).


RESULTS
Clinical findings included loss of tapetal hyperreflectivity. The mode of inheritance was autosomal recessive. An early dramatic reduction of cone-specific ERG amplitude with a more modest reduction in rod b-wave amplitude was demonstrated. Progressively, rod specific responses diminished until there were no recordable responses to the ERG stimuli at 40 weeks of age. Morphologic changes confirmed early cone inner and outer segment loss. Other abnormalities included opsin mislocalization and outer nuclear layer thinning due to the subsequent loss of rod photoreceptors.


CONCLUSIONS
A novel canine cone-rod dystrophy has been identified.
Turney
Clare
C
UCL Institute of Ophthalmology, London, United Kingdom.
Chong
N H Victor
NH
Alexander
Robert A
RA
Hogg
Chris R
CR
Fleming
Lorraine
L
Flack
Deborah
D
Barnett
Keith C
KC
Bird
Alan C
AC
Holder
Graham E
GE
Luthert
Philip J
PJ
D000818:Animals; D002452:Cell Count / Q000662:veterinary; D004283:Dog Diseases / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D004285:Dogs; D003576:Electron Transport Complex IV / Q000378:metabolism; D004596:Electroretinography / Q000662:veterinary*; D005260:Female; D005808:Genes, Recessive; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006651:Histocytochemistry / Q000662:veterinary; D007124:Immunoenzyme Techniques / Q000662:veterinary; D008297:Male; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism / Q000473:pathology*; D012160:Retina / Q000503:physiopathology*; D012162:Retinal Degeneration / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D017299:Rod Opsins / Q000378:metabolism; D016708:Synaptophysin / Q000378:metabolism
D005904:Glial Fibrillary Acidic Protein; D017299:Rod Opsins; D016708:Synaptophysin; D003576:Electron Transport Complex IV