Australian Shepherd Health & Genetics Institute

Australian Shepherd Health & Genetics Institute

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Cone Degeneration


What is cone degeneration (CD)?

CD causes day blindness; affected dogs can’t see in bright light but have normal vision when the light level is low.

 How do I know my dog has CD?

If the dog shows signs of vision loss in the daytime but not in the dark it should be checked by a veterinary ophthalmologist.  If the dog is found to have retinal degeneration the DNA test should be done to confirm the diagnosis.

What does having CD mean for my dog?

Your dog will have increasing vision loss to the point of blindness in bright light, and normal vision in very low light.  Vision will be impaired to some degree in intermediate light levels.  The disease is not painful.

How common is CD in Aussies?

Unknown but probably rare.

Is CD inherited?

Yes.  It is recessive.

Is there a DNA test?

Yes.  Dogs with two copies of the mutation are affected, dogs with one copy are carriers.  Because this disease causes blindness, parents, full siblings and offspring, if any, of affected dogs and any that are found to have even one copy of the mutation should be tested if they are used for breeding.  As additional affected or carrier dogs are identified via testing, their untested first-step relatives who are to be used for breeding should be tested.

What does CD mean for my breeding program?

Don’t breed affected dogs.  Breed carriers (parents of affected dogs or those with one mutation) only to clear-tested mates.  Preference should be given to clear-test offspring to carry on with.