A novel method for objective vision testing in canine models of inherited retinal disease.
OBJECTIVE
The use of canine models of retinal disease in the development of therapeutic strategies for inherited retinal disorders is a growing area of research. To evaluate accurately the success of potential vision-enhancing treatments, reliable methods for objectively assessing visual function in canine models is necessary.


METHODS
A simple vision-testing device was constructed that consisted of a junction box with four exit tunnels. Dogs were placed in the junction box and given one vision-based choice for exit. The first-choice tunnel and time to exit were recorded and analyzed. Two canine models of retinal disease with distinct molecular defects, a null mutation in the gene encoding the alpha subunit of rod cyclic GMP phosphodiesterase (PDE6A), and a null mutation in the gene encoding a retinal pigment epithelium-specific protein (RPE65) were tested and compared to those in unaffected dogs.


RESULTS
With the use of bright light versus dim red light, the test differentiated between unaffected dogs and dogs affected with either mutation with a high degree of certainty. The white-light intensity series showed a significantly different performance between the unaffected and affected dogs. A significant difference in performance was detected between the dogs with each mutation.


CONCLUSIONS
The results indicate that this novel canine vision-testing method is an accurate and sensitive means of distinguishing between unaffected dogs and dogs affected with two different forms of inherited retinal disease and should be useful as a means of assessing response to therapy in future studies.
Gearhart
Patricia M
PM
Department of Small Animal Clinical Sciences, Michigan State University College of Veterinary Medicine, East Lansing, Michigan 48824, USA. gearhart@cvm.msu.edu
Gearhart
Chris C
CC
Petersen-Jones
Simon M
SM
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D002352:Carrier Proteins / Q000235:genetics; D002755:Choice Behavior / Q000502:physiology; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6 / Q000235:genetics; D004195:Disease Models, Animal; D004283:Dog Diseases / Q000175:diagnosis* / Q000235:genetics; D004285:Dogs; D004596:Electroretinography; D005136:Eye Proteins / Q000235:genetics; D005189:False Positive Reactions; D005260:Female; D008027:Light; D008297:Male; D009154:Mutation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012160:Retina / Q000473:pathology*; D012162:Retinal Degeneration / Q000175:diagnosis / Q000235:genetics / Q000662:veterinary*; D012680:Sensitivity and Specificity; D014787:Vision Tests / Q000662:veterinary*; D014792:Visual Acuity / Q000502:physiology
D002352:Carrier Proteins; D005136:Eye Proteins; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6