Day Blindness, Cone Degeneration, Achromatopsia

Affected dogs may blink repeatedly in daylight, shake their heads, or seek out areas with dimmer light. Affected puppies may bump into objects that unaffected puppies easily avoid, and dogs may be fearful or aggressive in unfamiliar settings.

Affected dogs develop day blindness and photophobia between eight and 12 weeks of age. Normal cone function can be detected by electroretinography (ERG) in very young cd-affected pups but begins to fail at six to 12 weeks of age. While cone function is absent in mature day blind dogs, rod photoreceptors remain functionally and structurally normal throughout the dog's life.

Throughout their life, this variant doesn’t result in changes to an affected dog’s retina upon physical examination. Instead, definitive diagnosis of photoreceptor dysfunction is by ERG, which records the electrical potentials of the retina in response to a light stimulus. Referral to a veterinary ophthalmologist may be needed for a definitive diagnosis.

There is currently no treatment for cone degeneration. However, gene therapy is an evolving field. In humans, deeply tinted glasses are used to help manage the symptoms.

Talk to your vet about your dog’s achromatopsia result so you can work together to plan their ongoing care and monitoring.

Limit your dog’s exposure to bright sunlight and provide shaded areas for outdoor activities.

If your dog seems sensitive to light, try using tinted dog goggles or visors made for pets to help them see more comfortably in bright environments.

This variant was first observed in Alaskan Malamutes and has subsequently been identified in Australian Shepherd-type dogs. Keep in mind that eyesight can deteriorate with age due to other causes. Please consult with your veterinarian should you have any concerns about your dog’s eyesight, even if they tested clear for this variant.

Penetrance: This is a recessive variant, that is, a dog requires two copies of the variant to show signs of Day Blindness (also known as Cone Degeneration or Achromatopsia) from the variant.

Gene

CNGB3

Inheritance type

recessive

Clinical category

Ophthalmologic

Citations

1. Sidjanin et al 2002
2. Yeh et al 2013

• Alaskan-type Husky
• Alaskan Malamute
• Australian Shepherd
• Australian Shepherd
• Miniature/MAS-type Australian Shepherd
• Siberian Husky