Canine Multifocal Retinopathy is one of two genetic disorders in which the mode of inheritance has been found.
PRA is the other.
CMR is an eye disorder which can cause of range of symptoms ranging from minor retinal folding, up to detached retinas.
Most of the time symptoms are minor, and sometimes symptoms are not even present. The minor symptoms range from
small folding in the retina (folds) to small patches of raised areas on the retina (geographic). Opthamologists say
that CMR probably does not affect vision much, it may or may not cause small areas of fuzzy vision, and might cause decreased
night vision. Geographic would cause larger patches of fuzzy vision than folding. (Per CERF doctor).
CMR affected dogs with folds can get CERFed, with a breeder option, but CMR affected dogs with geographic patches can't
get CERFed. Nor can detached retina, but that is the worse case scenerio in CMR and rarely seen.
CMR is inherited as a recessive gene meaning the dog must have two copies of the gene to be affected. Carriers
(dogs with only one copy) are phenotypically normal, but carry one copy for the CMR gene.
Since the symptoms of CMR are mostly minor, it isn't widely tested for, but we still feel it is important to breed out,
especially since there is a DNA test for it. Affected and carrier dogs should be bred to non-carrier dogs (dogs carrying
two copies of the normal gene).
Testing is done by drawing blood and sending it to Optigen for DNA testing:
Dogs can also be cleared by parentage (both parents are DNA clear, or all four grandparents DNA Clear, etc.)