Progressive retinal atrophy

Causes of PRA in dogs

PRA is a genetic disease that is passed on from parents to offspring. There are various forms of PRA, which differ in the way they are inherited, the time of onset and the course of the disease. The most common forms are

• Generalized PRA (GPRA): This form affects many dog breeds and can occur at an early or late stage. In GPRA, the rods are usually affected first, leading to night blindness. Later, the cones are also affected, leading to day blindness and color blindness. Blindness is usually complete by the age of 3 to 5 years.
• Central Progressive Retinal Atrophy (CPRA): This form mainly affects Labrador Retrievers and Golden Retrievers. In CPRA, the cones are affected first, which leads to reduced visual acuity and a restricted field of vision. The rods are affected later, leading to night blindness. Blindness is usually complete by the age of 6 to 8 years.
• X-linked Progressive Retinal Atrophy (XLPRA): This form mainly affects Siberian Huskies and Samoyeds. In XLPRA, the responsible gene is linked to the X chromosome, which means that only male dogs can develop the disease. Female dogs are only carriers of the gene. In XLPRA, both the rods and the cones are affected, which leads to rapid blindness at the age of 1 to 2 years.

The exact genes responsible for PRA are not yet known for all dog breeds. However, there are genetic tests for some breeds that can determine the risk of PRA. These tests can help to reduce the spread of PRA by using only healthy or free dogs for breeding.

Symptoms of PRA in dogs

The symptoms of PRA in dogs depend on the form and stage of the disease. The first signs may be

• Difficulty seeing at dusk or in the dark
• Enlarged or shiny pupils
• Increased gleaming of the eyes in the light
• Cautious or anxious behavior
• Bumping into objects or walls
• Reduced activity or playfulness

In advanced stages, the following symptoms may occur:

• Difficulty seeing in daylight or bright light
• Limited or lost field of vision
• Color blindness
• Gray or green veil over the eyes
• Complete blindness

PRA is a painless condition that does not directly affect the dog. However, blindness can lead to stress, anxiety or depression, which reduces the dog's well-being and quality of life.

Diagnosis of PRA in dogs

The diagnosis of PRA in dogs is made by a thorough examination of the eyes by a vet or an eye specialist. This involves looking at the retina and other structures of the eye using a special device called an ophthalmoscope. Various tests are also carried out to check the function of the retina, such as

• Electroretinography (ERG): This test measures the electrical activity of the retina when it is exposed to light stimuli. In PRA, this activity is reduced or absent.
• Optical coherence tomography (OCT): This test produces a detailed image of the retina and its layers. In PRA, these layers are thinner or destroyed.
• Fluorescein angiography (FA): This test uses a special color that is injected into the blood vessels of the eye. The color is then recorded with a camera to assess the blood flow in the retina. In PRA, this blood flow is reduced or interrupted.

In addition to these tests, a genetic test can also be carried out to determine the presence or absence of the gene for PRA. This test can also be performed on healthy dogs to determine their status as carriers or carriers.

Treatment of PRA in dogs

Unfortunately, there is currently no effective treatment or cure for PRA in dogs. The disease is progressive and irreversible. However, there are some ways to support the dog and improve their quality of life. These include:

• Regular check-ups with a veterinarian or eye specialist to monitor the progression of the disease and to detect and treat potential complications such as cataracts or glaucoma.
• A balanced diet with high-quality ingredients and supplements that can promote eye health, such as antioxidants, omega-3 fatty acids or lutein.
• A safe and familiar environment for the dog in which he feels comfortable and oriented. Sudden changes should be avoided, such as rearranging furniture or adding new objects. In addition, potential sources of danger such as stairs or sharp edges should be secured.
• Gentle and patient care of the dog to give him security and confidence. Clear and consistent commands should be used to guide and warn the dog. Positive reinforcements such as praise or treats should also be given to motivate the dog and boost its confidence.
• Appropriate physical and mental stimulation of the dog that challenges its senses and intelligence. Activities should be chosen that are fun for the dog and appropriate to its abilities. For example, games with sounds or smells can be used to engage and reward the dog.