Dog model relevant to retinal disease study in humans

The dog model is an appropriate choice for developing and testing novel therapies applicable to human patients because the approximately 300 dog breeds are genetically isolated populations. Furthermore, it is believed their phenotype is similar to that of humans, according to Gustavo Aguirre, VMD, PhD, professor of ophthalmology and medical genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia.

"All of the species and animal models that you're using have very valid answers, assuming you have the right questions, to examine mechanisms by which the retina degenerates and to devise treatments," Dr. Aguirre said.

Many advances have made the dog model, in particular, more useful in studying eye disease, he continued. These include the recent release of the dog genome draft sequence and the ongoing development of single nucleotide polymorphism chips that can be used for disease association studies.

Progressive rod-cone degeneration (PRCD) is one disease in which gene discovery in dogs can be applied to humans. A localized area for closer study has been identified, and the same mutation has been found in all 17 dog breeds known to be affected by PRCD. So far, one patient with the same mutation has been identified and examined. The use of phenotype-directed candidate gene analysis to study canine multifocal retinopathy also has yielded correlations to human disease.

Research in animal models has also led to therapeutic results that may be applicable to humans. Canines with a form of Leber congenital amaurosis have recovered retinal function following a single treatment with gene therapy, Dr. Aguirre reported.