Tellier's AKC  Boston Terriers
Long Lane, Missouri 
(417) 718-5626

Canine Multifocal Retinopathy (CMR) is an autosomal recessive eye disorder known to affect Australian Shepherds, English Bulldogs, American Bulldogs, and many others. Autosomal recessive disorders are disorders that can be passed from either parent and require two copies of the gene to show symptoms.

 

The mutation causes raised lesions to form on the retina of the eye. These lesions can alter the appearance of the eye but usually do not affect sight. The lesions may disappear or may result in minor folds on the retina. Symptoms of the mutation usually appear when a puppy is only a few months old, and generally do not worsen over time.

Because CMR1 is a recessive disorder, a dog must have two copies of the mutation in order for the disease to manifest.

 

This means that a dog can have one copy of the mutation and not experience any signs or symptoms of CMR1. This dog would be known as a carrier. The carrier can then pass on either the normal gene or the mutated gene to any offspring. If two carriers are bred, there is a 25% per puppy that they will develop symptoms of CMR1. Additionally, since retinal defects can be caused by other conditions, testing can verify that a dog actually has CMR rather than some other eye condition.