Abnormal dark-adapted ERG in cats heterozygous for a recessively inherited rod-cone degeneration.
OBJECTIVE
To study retinal function in cats homozygous and heterozygous for a recessively inherited rod-cone degeneration.


METHODS
Dark-adapted electroretinograms (ERGs) were performed on early affected, heterozygous (ophthalmoscopically normal), and clinically normal, nonrelated cats. Responses to blue stimuli over a 3.9-log unit range were recorded.


RESULTS
Lower b-wave amplitudes than normal were observed in heterozygotes and early affected cats. The amplitudes of the heterozygotes took an intermediate position between normal and early affected cats. Normalized amplitude/intensity data suggest a normal dynamic range in carriers. B-wave implicit times in carriers were comparable to those of normal cats.


CONCLUSIONS
These results show that heterozygotes have an altered retinal function, although they are ophthalmoscopically normal. It is difficult to electrophysiologically differentiate heterozygotes from affected cats with the very early stage of retinal degeneration.
Ekesten
Björn
B
Department of Clinical Sciences, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, Uppsala, Sweden. Bjorn.ekesten@kirmed.sli.slu.se
Narfström
Kristina
K
D000818:Animals; D016022:Case-Control Studies; D002371:Cat Diseases / Q000235:genetics* / Q000503:physiopathology*; D002415:Cats; D003623:Dark Adaptation / Q000502:physiology*; D004596:Electroretinography / Q000662:veterinary; D005260:Female; D020022:Genetic Predisposition to Disease; D008297:Male; D010375:Pedigree; D010786:Photoreceptor Cells / Q000503:physiopathology*; D012162:Retinal Degeneration / Q000235:genetics / Q000503:physiopathology / Q000662:veterinary*