Eye Problems
Goldens are susceptible to various conditions that can affect their sight, such as Progressive Retinal Atrophy (PRA) and Hereditary Cataracts (HC). Additionally, there are other conditions, like Multifocal Retinal Dysplasia (MRD) and Post Polar Cataract (PPC), that do not impact their vision. In Australia, breeders diligently screen their dogs annually for these conditions. At GRCWA, we understand the importance of ensuring the health and well-being of golden retrievers, which is why we prioritise regular screenings to maintain the breed’s overall health.
Progressive retinal atrophy is characterised by bilateral degeneration of the retina resulting in progressive vision loss leading to total blindness.
More than 20 mutations have been identified in different breeds that result in canine progressive retinal atrophy (PRA). Golden Retrievers are affected by more than one form of PRA and mutations in three distinct genes having been identified. Two of such mutations are known as PRA1 and PRA2. PRA1 results from a mutation in the SLC4A3 gene and accounts for over 60% of diagnosed PRA cases in the Golden Retriever. PRA2 results from a mutation in the TTC8 gene and accounts for 30% of Golden Retrievers diagnosed with PRA. Both mutations are autosomal recessive thus two copies of the same affected gene must be present for the disease to be observed and both males and females are equally affected. Presence of one copy of each affected genes in the same dog will not cause blindness, two copies of the mutated gene are needed to produce the disease.
In affected dogs, clinical signs of PRA1 appear around 6 years of age. Clinical symptoms of PRA2 appear around 4 years of age. Breeding two carriers with the same mutation is predicted to produce 25% affected puppies and 50% carriers. Mating a carrier of PRA1 with a carrier of PRA2 will not produce affected animals.
Testing for PRA1 and 2 assists owners and breeders in identifying affected and carrier dogs. Breeders can use results from the tests as a tool for selection of mating pairs to avoid producing affected dogs. Genetic testing for PRA1 and 2 is recommended for Golden Retrievers.
Hereditary cataracts is an inherited eye disease in dogs. Cataracts are opacities in the lens of the eye caused by structural changes in lens proteins. A normal lens allows light to pass through it to the Retina in the back of the eye. Light cannot pass through the parts of the lens affected by cataracts and vision becomes blurry. Dogs with Hereditary cataracts most commonly present within a few weeks to months after birth with small cataracts that are visible on a veterinary eye exam. Cataracts from this disease will eventually affect the whole lens in both eyes leading to complete blindness between 2-3 years of age. Of note, not all forms of cataracts are inherited and environmental factors such as UV damage can also play a role in the severity of disease. Fortunately, the age of onset, appearance and evolution of the cataracts which are hereditary are usually quite specific, enabling inherited cataracts to be distinguished from other non-inherited types of cataracts.
Posterior polar subcapsular cataracts (PPC) better known as the star cataract is a hereditary cataract seen in the golden retriever. It is usually in both eyes and becomes apparent between 6 to 18 months of age. Some dogs may develop this problem as late as 6 to 7 years of age. This cataract may be slowly progressive, but rarely interferes with vision. It is advised not to breed from affected animals as mating’s with affected dogs have produced litters of blind pups. Despite the large number of breeds affected by HC only a single gene, the transcription factor HSF4, has been implicated in the development of cataracts in dogs to date. However, HSF4 has been excluded from involvement in the development of PPC in the Golden Retriever.
Treatment of Retinal Dysplasia in Dogs
There is no treatment for this condition. While there is ongoing research, there is nothing yet to prevent this condition from occurring. Prevention comes in the form of not breeding your dog if he has this condition as it will pass the genes on to the next generation
Glaucoma is caused by Increased pressure within the eye. The increased pressure can rapidly cause blindness, and pain. The normal pressure within the eye is 10 to 25 mm Hg. When the pressure is increased (usually > 30 mm Hg) a diagnosis of glaucoma is made.
Primary Glaucoma – in some dogs the outflow of fluid from the eye is blocked by an abnormal drainage angle.
Secondary Glaucoma – develops due to inflammation of the eye (uveitis), lens luxation, blood in the eye (hyphaemia), or due to growths inside the eye