Overview of Feline Progressive Retinal Degeneration (PRD)
Progressive retinal degeneration or atrophy (PRD, PRA) is premature degeneration (deterioration) of the photoreceptor cells of the retina. There are two types of photoreceptors in the retina and these are the light-sensitive rods and cones. They are responsible for detecting light and converting it into an electrical signal that travels to the brain. When the photoreceptor cells deteriorate, vision is lost because the animal has no way to generate an image from the light reaching the retina.
PRA/PRD is in cats initially affects the rods. The rods are responsible for dim light vision; therefore, the cat loses its nighttime vision first. The disorder is progressive and eventually the cones are affected. Over time, the cat slowly goes completely blind. The disease affects both eyes at the same time.
Most cats are seen in the late stages of disease and have advanced changes in their retinas because they compensate very well as their vision slowly deteriorates. Sometimes the blindness can appear to be sudden in onset (even though it has been developing for months) because the cat may show almost no signs until the last bit of vision has been lost.
PRA in cats is rare in the United States. It is seen most often in purebred cats, such as the Abyssinian, Persian, and Siamese. It is seen sporadically in domestic shorthair and other mixed breed cats. In the Abyssinian, the disease is inherited as a dominant trait, but the inheritance pattern is unknown for other cats.
Below is an overview of Progressive Retinal Degeneration (PRD) in Cats followed by more detailed information on the diagnosis and treatment of this disease.
What to Watch For
Diagnosis of Progressive Retinal Degeneration (PRD) in Cats
Diagnostic tests are needed to recognize PRA/PRD and exclude other diseases. Your veterinarian will probably take a complete medical history and perform a thorough physical examination.
A complete ophthalmic examination is indicated and involves all of the following tests. Your veterinarian may refer your cat to a veterinary ophthalmologist for completion of some of these tests:
If your veterinarian is concerned that some disease other than PRA is the source of the cat’s blindness, then medical tests to rule out other causes may include the following:
PRA can sometimes be confirmed at the time of retinal examination because it causes characteristic changes in the appearance of the retina. Early stages of the disease can be more difficult to diagnose, and in that instance the disease can be detected with the following test:
Treatment of Progressive Retinal Degeneration (PRD) in Cats
No therapy is available to prevent, slow the progression of, or reverse the degenerative changes of PRA.
Early diagnosis of PRA using electroretinography is most important in catteries to eliminate individuals from the breeding pool that are either clinically affected or represent genetic carriers of the disease.
Care consists of providing a consistent and safe environment for pets with vision loss. Considerations include: