NEURONAL CEROID LIPOFUSCINOSIS
Neuronal Ceroid Lipofuscinosis storage disease is a progressive degeneration disease of the central nervous system. In Golden Retrievers, NCL is caused by a 2 base pair deletion in the CLN5 gene causing causing a frameshift and premature termination codon.
Affected Golden Retrievers begin to develop signs of the disease around 13 months old. Often the first sign of NCL is a loss of coordination during basic movements including walking, running, climbing stairs, particularly when excited. As the disease progresses, the loss of coordination becomes evident even when the dogs is calm; the dogs may also experience tremors, seizures, or blindness. Compulsive behaviors, anxiety, and loss of previously learned behavior is also common. Affected dogs may also become agitated or aggressive as the disease continues to progress. Due to the severity of the disease and loss of quality of life, most affected dogs are euthanized by 2-3 years of age.
Degenerative Myelopathy (DM) is a progressive neurological disorder that affects the spinal cord of dogs. Dogs that have inherited two defective copies will experience a breakdown of the cells responsible for sending and receiving signals from the brain, resulting in neurological symptoms.
The disease often begins with an unsteady gait, and the dog may wobble when they attempt to walk. As the disease progresses, the dog's hind legs will weaken and eventually the dog will be unable to walk at all. Degenerative Myelopathy moves up the body, so if the disease is allowed to progress, the dog will eventually be unable to hold his bladder and will lose normal function in its front legs. Fortunately, there is no direct pain associated with Degenerative Myelopathy.
MD is a mutation of the dystrophin gene that causes a deficiency of dystrophin proteins in Golden Retrievers. The lack of dystrophin proteins leads to the progressive degeneration of skeletal and cardiac muscles. The disease is similar to the human disease, muscular dystrophy.
Symptoms appear relatively quickly, at about six weeks to two months of age. A dog with muscular dystrophy will exhibit muscle weakness, difficulty standing or walking normally, and difficulty swallowing. Symptoms can range from relatively mild to severe, but GRMD is generally fatal at about 6 months of age.
Ichthyosis is an autosomal recessive genetic mutation that affects the skin of Golden Retrievers. The mutation prevents the outer layer of the epidermis from forming properly, resulting in skin that becomes darkened and thick, with excessive flaking.
The name "Ichthyosis" is derived from the Greek word for fish. This describes the skin's resemblance to fish scales. The most common symptom of ICH-A is excessive flaking of the skin. Other symptoms include areas of hardened skin and hyperpigmentation, which may make the skin appear dirty or blackened. Symptoms can be mild or severe. Evidence of the disease may be detected when the dog is still a puppy, but symptoms may take a year or more to develop. Additionally, symptoms can improve or worsen, depending on stress and hormonal cycles.
Ichthyosis is generally not dangerous to a dog's health, but can be unsightly and uncomfortable for the dog.
PROGRESSIVE RETINAL ATROPHY
Progressive Rod-Cone Degeneration, or PRA-prcd, is a form of Progressive Retinal Atrophy (PRA) in which the cells in the dog's retina degenerate and die. PRA for dogs is similar to retinitis pigmentosa in humans. Most affected dogs will not show signs of vision loss until 3-5 years of age. Complete blindness can occur in older dogs. Progressive Rod-Cone Degeneration is a form of PRA known to affect over 40 different breeds.
The retina is a membrane located in the back of the eye that contains two types of photoreceptor cells. These cells take light coming into the eyes and relay it back to the brain as electrical impulses. These impulses are interpreted by the brain to "create" images. In dogs suffering from PRA-prcd, the photoreceptors begin to degenerate, causing an inability to interpret changes in light. This results in a loss of vision. Rod cells, which normally function in low-light or nighttime conditions, begin to degenerate first. This leads to night-blindness. The cone cells, which normally function in bright-light or daytime conditions, will deteriorate next. This often leads to complete blindness over a period of time.
PRA GR-PRA1 & GR-PRA2
(PRA1) & (PRA2)
Progressive Retinal Atrophy (PRA) is a category of genetic mutations that cause vision loss and blindness. Photoreceptor cells in the retina begin to degenerate, typically progressing from a loss of night vision to complete blindness.
PRA affects many different dog breeds, and these mutations are breed-specific. In Golden Retrievers, two mutations have been identified in addition to prcd-PRA known as GR-PRA1 and GR-PRA2.