Warning Signs of PRA in Black Labs

Progressive Retinal Atrophy (PRA), an incurable canine genetic disorder common to several breeds, gradually causes blindness in affected dogs. In Labrador retrievers, the disease is autosomal recessive, meaning that the faulty gene does not appear on sex chromosomes; the dog must inherit a copy of the gene from both parents to get PRA, though a healthy dog can pass the disease to offspring if it mates with another carrier. Warning signs include night blindness, abnormally enlarged pupils and cataract formation.

  1. Night Blindness

    • PRA gets worse over time, but night blindness often provides an early warning of the disease's onset. Labrador retrievers exhibit the "rod-cone degeneration" form of PRA, so when a dog has trouble seeing at night, this indicates degeneration of the retina's photoreceptive "rod" cells, which allow eyes to see in low light. Common behaviors that suggest night blindness include disorientation and nervousness around darkened staircases.

    Enlarged Pupils and Reflective Eyes

    • Unusually dilated pupils may also indicate that a Labrador retriever suffers from PRA. Once photoreceptors stop working properly, a dog's eyes compensate by opening pupils wider to let more light through to the retina. Dog owners may notice not only dilated pupils, but also shinier-than-normal eyes. PRA causes retinal thinning, which makes the retina more reflective. This increased reflectivity becomes especially obvious in dogs with wide-open pupils.

    Cataracts

    • A Labrador retriever with PRA may develop cataracts in the later stages of the disease, which can make the disease more difficult to diagnose because the cloudy tissue obscures the retina. Veterinarian Charles Martin notes that dog owners may blame their dogs' blindness on cataracts rather than PRA, but he suggests that the breakdown of retinal photoreceptor cells caused by PRA may release chemicals that cause cataract formation.

    Lack of Effective Treatment and Adjusting to Blindness

    • Veterinarians have not found a cure or effective treatment for PRA. Martin writes that, "Various vitamin supplements with antioxidants are frequently prescribed and are usually considered placeboes for the owner as well as the dispensing veterinarian," suggesting that these treatments do little for the dogs. The American Kennel Club's Canine Health Foundation notes, however, that because PRA takes time to cause total blindness, dogs can learn to live with their disability and function normally so long as their owners do not make drastic changes to their home environment.