Day Blindness


Day Blindness (also known as Cone Degeneration (cd) or Achromatopsia) is a progressive, non-painful disorder of the retina that affects color vision and light perception. Cone cells not only register color, but also allow the dog to adjust their eyes to bright light. Affected dogs develop day-blindness and photophobia (light sensitivity). Symptoms are present only in bright light; vision in dim light is normal.

  • Signs and symptoms

    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.

    Uncover health risks with Embark

    Embark Breed + Health Test

    Original price:


    Sale price:



    Embark for Breeders Dog DNA Test

    $129 - $159


  • Diagnosis

    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.

  • Treatment

    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.

  • What to do if your dog is at risk


    • Help affected dogs navigate their homes and the outside world by keeping your furniture in the same location, adjusting light exposure, making sure they are on a leash when in unfamiliar territory, and training them to understand verbal commands.

  • Genetic Information

    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.

    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 names:

    CNGB3 ‐ chr

    Inheritance type:


  • Breeds affected

    This health condition affects the following breeds

Learn about your dog’s unique genetic health

Dog owners

Breed identification, health and trait insights, personalized care recommendations, and the world’s first canine relative finder—all in one leading dog DNA test.

Learn about the report for dog owners
Shop the test
Breeding programs

Embark’s test for breeding programs is one comprehensive DNA test designed with your needs in mind.

Learn about the report for breeders
Shop the test