Canine Multifocal Retinopathy Type 1 (CMR1)

Canine Multifocal Retinopathy 1

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Price: $45.00Price: £40.00

Breeds: Alapaha Blue Blood Bulldog, American Bulldog, American Bully, Anatolian Shepherd, Aussiedoodle, Australian Bulldog, Australian Mix, Australian Mountain Doodle, Australian Shepherd, Australian Shepherd/Border Collie, Bandog, Boerboel, Boston Terrier, Brazilian Terrier, British Bulldog, Bulldog, Bulldog Mix, Bullmastiff, Cane Corso, Dogue de Bordeaux, English Bulldog, English Mastiff, Exotic Bully, French Bulldog, French Mastiff, Frenchton, Great Pyrenees, Havanese, Havapoo, Mastiff, Miniature American Shepherd, Miniature Australian Shepherd, Miniature English Bulldog, Miniature Olde English Bulldog, Mixed Breed, Neapolitan Mastiff, Olde English Bulldogge, Perro de Presa Canario, Pomsky, Shorty Bull, Southern Cross Bulldog, Tibetan Mastiff, Toy Australian Shepherd, Unspecified


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.

Possible Results

Genotype Description
CMR1/CMR1 Affected: Dog has two copies of the CMR1 mutation and may develop symptoms of the disorder. The dog will always pass on the mutation to all offspring.
n/CMR1 Carrier: Dog has one copy of the Canine Multifocal Retinopathy Type 1 mutation. The dog is not affected by CMR1 but may pass the mutation to offspring.
n/n Clear: Dog is negative for the mutation associated with CMR1.


Grahn BH, Philibert H, Cullen CL, Houston DM, Semple HA, Schmutz SM. Multifocal retinopathy of great Pyrenees dogs. Vet Ophthalmol. 1998;1(4):211-221. [PubMed: 11397233]

Guziewicz KE, Slavik J, Lindauer SJ, Aguirre GD, Zangerl B. Molecular consequences of BEST1 gene mutations in canine multifocal retinopathy predict functional implications for human bestrophinopathies. Invest Ophthalmol Vis Sci. 2011 Jun; 52(7):4497-505. [PubMed: 21498618]