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Thank you to Helen Newman for putting together this article for SCARF.
Retinal dysplasia: The term dysplasia means a defective development of an organ or structure. Merck, CERF and the Diplomates of the American College of Veterinary Ophthalmology explain it as follows: “it is a nonprogressive, abnormal development of the retina that is present at birth. It occurs when the 2 primitive layers of the retina do not form together properly. The disorder can be inherited or it can be caused by a prenatal infection (e.g. herpes virus or parvovirus)”.
There are 3 types:
- Focal or multifocal retinal dysplasia: folds or small rosettes, single or multiple, may become less evident with maturity (vision impairment is unknown, but blinds spots can occur)
- Geographic retinal dysplasia: irregularly shaped areas of the retinal tissue that appear similar to a horseshoe in shape. These lesions can change in appearance with age. These lesions can co-exist with folds or rosettes. As the folds may disappear later when the retinas mature, this type of dysplasia will persist. (some degree of visual impairment and possibly blindness)
- Complete retinal dysplasia with detachment: most severe, often leads to blindness and secondary problems such as glaucoma, has been linked to skeletal defects in the labrador (Retinal Dysplasia/Oculoskeletal Dysplasia 1 - RD/OSD1) and Samoyed (Retinal Dysplasia/Oculoskeletal Dysplasia 2 - RD/OSD2).
Oculoskeletal Dysplasia (RD/OSD2): In this inherited disease there are both eye and bone defects. In addition to the retinal folds and other malformations of the retina, the legs are shorter and there may be other skeletal malformations. It may also be described as dwarfism. The disease is inherited as an autosomal recessive with a heterozygous effect, meaning that dogs with one copy of the gene may still have retinal defects.
Signs and Symptoms
There are no outward symptoms of the eye but signs that the puppy/dog is having difficulty seeing would include frequently bumping into objects, less activity, and possibly timid or fearful. An eye examination by an ophthalmologist should be performed.
The skeletal malformations in RD/OSD2 may be recognized by observation.
The cause of retinal dysplasia in most dogs is genetic in origin and a congenital disease. Other causes include viral infections, vitamin A deficiency, x-ray radiation, certain drugs, and intrauterine trauma. Simple autosomal recessive inheritance has been suspected in Akitas, American Cocker Spaniels, Australian Shepherds, Bedlington Terriers, Beagles, Dobermans, English Springer Spaniels, Labradors, Rottweilers, Old English Sheepdogs, Sealyham Terriers, and Yorkshire Terriers. In many breeds ophthalmologists and researchers have not determined exactly how retinal dysplasia is passed.
In the Labrador and Samoyed the autosomal recessive inheritance of a combination of retinal dysplasia and skeletal defects (dwarfism) has been described (RD/OSD1 - Labrador; RD/OSD2 - Samoyed).
- Toxicity (something in the environment that the bitch may be exposed to during pregnancy or the newborn is exposed to)
- Infection during pregnancy (e.g herpes virus and possibly parvovirus)
- A trauma at a very young age
- Inherited genetic make up for RD/OSD2
Retinal dysplasia can be detected as early as 6-8 weeks during a CERF examination. However, because the size of the eye is small and young puppies are often wiggling during examination, a re-examination is recommended 6 months later in order for the ophthalmologist to better see the back of the eye is recommended.
7/25/2008 - Wisdom Health (formerly Optigen) has a DNA test available for the gene mutation that causes inherited Retinal Dysplasia/OculoSkeletal Dysplasia (RD/OSD2, ie.,dwarfism) in the Samoyed. For more information:
Note: Treatment of animals should only be performed by a licensed veterinarian. Veterinarians should consult the current literature and current pharmacological formularies before initiating any treatment protocol.
- There is no treatment for retinal dysplasia.
- Annual eye checks with an ophthalmologist
- An animal with retinal dysplasia should only be bred if shown to have normal/clear DNA test results for the RD/OSD2 mutation. Carriers should not be bred.
Aroch,I, Ofri R. and Alzenberg, I., Haematological, ocular and skeletal abnormalities in a Samoyed family. The Journal of Small Animal Practice. Vol.37:7, p.333-339, 1996 link to abstract
American College of Veterinary Ophthalmologist 1999
Howell,D.M. Stankovics, M.E., Sarna C.S. and Aguirre G.D. The geographic form of retinal dysplasia in dogs is not always a congenital abnormality. Veterinary Ophthalmology p. 61-66, 1999. link to abstract
MacMillian A.D. and Lipton D.E., Heritability of Multifocal Retinal Dysplasia in American Cocker Spaniels, JAVMA 1978: vol. 172:5 p. 568-572
Meyers V.N., Jezyk P.F., Aguirre G.D. and Paterson D.F., Short-limbed dwarfism and ocular defects in the Samoyed dog, JAVMA, vol. 183:9, p. 975-979, Nov. 1, 1983. link to abstract Willis, Malcolm B. “Genetics of the Dog” Howell Book House 1989.