Disease overview

Rod-Cone Dysplasia 4 (RCD4) is a form of late-onset, progressive retinal atrophy. This is a non-painful eye disorder that affects both types of photoreceptors: rods and cones. Rod cells are responsible for vision in low light conditions and for detecting and following movement, while cone cells detect color and adjust brightness, but do not work as well in low light. RCD4 causes retinal degeneration between 7 to 12 years of age and can lead to complete blindness.

Gene name

PCARE

Inheritance

Autosomal recessive with potentially incomplete penetrance

Signs and symptoms

Progressive retinal atrophy is typically characterized by a loss of vision over time, which can allow for a dog to adapt more easily. Signs of change in the tapetum, which is the reflective surface of the eye, may begin as early as 5 years of age. These changes first cause night blindness, progressing to vision loss during the day and then often to complete blindness for most dogs. Changes in behavior such as reluctance to go down stairs, reluctance to go into a dark room, and bumping into door frames may be signs that a dog is experiencing vision loss.

How is it diagnosed

Thorough examination of the eyes and clinical signs. A veterinary ophthalmologic exam can determine if there are changes in the eye that have or will lead to vision loss. Genetic testing is necessary to determine if there is an underlying genetic cause, which can assist veterinarians with diagnosis and help breeders identify affected and carrier dogs.

Breeds at higher risk

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Citations

Downs LM, Bell JS, Freeman J, Hartley C, Hayward LJ, Mellersh CS. Late-onset progressive retinal atrophy in the Gordon and Irish Setter breeds is associated with a frameshift mutation in C2orf71. Anim Genet. 2013 Apr;44(2):169-77. doi: 10.1111/j.1365-2052.2012.02379.x. Epub 2012 Jun 12. PMID: 22686255.

Disclaimer

Disease diagnosis and treatment should always be performed by a veterinarian. The following information is for educational purposes only.