Stargardt Disease in Labrador Retrievers

Stargardt Disease

Stargardt Disease (STGD, also known as Stargardt’s Disease) is a hereditary eye condition in Labrador Retrievers and related breeds that causes degeneration (deterioration) of the retina. As a result, the dog gradually loses more and more vision, which can eventually lead to near-total blindness.

Symptoms

Dogs with Stargardt Disease appear to see normally at a young age, but as they get older, it becomes increasingly noticeable that their vision is deteriorating. First, their vision in daylight worsens, and later, their vision in dim light also declines. Affected dogs will always retain some level of vision—they do not become completely blind.

Young dogs (under 2 years of age) often show no visible symptoms. Occasionally, a dog may miss a bird or dummy that falls in the distance during hunt training. From around the age of one year, a veterinary ophthalmologist may be able to detect retinal abnormalities, for example during an ECVO eye exam. However, these abnormalities are so minor at this stage that they are easy to overlook.

Middle-aged dogs (5 to 7.5 years old) can generally still see well, but there may be some uncertainty about their vision in daylight. At this age, a veterinary ophthalmologist can detect retinal abnormalities.

In older dogs (10 years and older), it is almost always evident that they have difficulty seeing in both daylight and dim light. In addition, their pupils are often dilated in daylight to allow more light into the retina, and the eyes respond differently to light.

A veterinary ophthalmologist can confirm whether the vision loss is due to Stargardt Disease or another condition through an eye examination, possibly supported by a DNA test.

What causes Stargardt Disease?

Stargardt is a hereditary disorder caused by a mutation in the ABCA4 gene. This mutation is autosomal recessive, which means that only affected dogs (with two faulty gene copies) show symptoms. Carriers (with one faulty and one normal gene) maintain normal vision but can still pass the faulty gene to their offspring.

Stargardt Disease occurs in Labrador Retrievers and in breeds where Labradors have been crossed in. In humans, a mutation in the same gene causes a similar condition, which is also called Stargardt Disease. The mutation in dogs was only discovered in 2019, after which the condition was named after the human version.

The mutation in the ABCA4 gene causes the retina to slowly degenerate. The retina contains photoreceptors, which are the cells that detect light. These photoreceptors are known as rods and cones. Cones detect daylight and allow for color vision. Rods detect light in dim conditions and darkness. In Stargardt Disease, the cones are mainly affected, but the rods are also impacted. This is why impaired vision in daylight is noticed earlier than in dim light.

My dog is affected or a carrier of Stargardt Disease—what to do?

A DNA test can determine whether your dog is clear, a carrier (one normal and one faulty gene), or affected (two faulty genes) by Stargardt Disease. Dogs that are affected will eventually develop symptoms, but there is no treatment available. The good news is that most dogs with Stargardt Disease can live relatively normal lives as household pets. However, some dogs may become anxious or struggle in unfamiliar situations due to their poor vision. As working or hunting dogs, they are usually no longer suitable.

Although most dogs can still enjoy a good quality of life as pets despite their poor vision, it is best to prevent dogs with Stargardt Disease from being born. This is possible with the help of a DNA test. If a carrier (or affected animal) is used for breeding, it is essential to always pair them with a clear (non-carrier) dog. This ensures that no affected puppies will be born.

Relevant tests

• H907