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Retinal pigment epithelial dystrophy in Briard dogs
R M Lightfoot1, L Cabral, L Gooch
1Royal Veterinary College, North Mymms, Hatfield.
Research in Veterinary Science
|January 1, 1996
Summary
Inherited retinal pigment epithelial dystrophy (RPED) in Briard dogs involves lipofuscin accumulation and retinal degeneration. This condition does not appear to stem from increased rod outer segment turnover or enzyme insufficiency.
Area of Science:
- Veterinary Ophthalmology
- Canine Genetics
- Retinal Diseases
Background:
- Inherited retinal pigment epithelial dystrophy (RPED) affects Briard dogs.
- Understanding the pathogenesis of RPED is crucial for canine eye health.
- Comparison with normal canine retinal aging provides insights.
Purpose of the Study:
- To histopathologically characterize RPED in Briard dogs.
- To compare RPED features with normal canine retinal aging.
- To investigate potential causes of RPED, including rod outer segment turnover and lysosomal enzyme activity.
Main Methods:
- Histopathological examination of canine retinas.
- Comparison of RPED in affected Briards with normal dogs and aging retinas.
- In vitro assay of acid phosphatase activity in retinal pigment epithelium (RPE).
- Intra-vitreal injection of radiolabelled leucine to assess rod outer segment turnover.
Main Results:
- RPED is characterized by lipofuscin-like inclusions in the RPE and secondary neuro-retinal degeneration.
- Photoreceptor loss in RPED resembles severe age-related changes.
- No significant variation in rod outer segment turnover was found in affected Briards.
- Acid phosphatase activity showed comparable regional variations in Briard and crossbred dogs.
Conclusions:
- RPED in Briards is unlikely due to increased rod outer segment turnover.
- A primary insufficiency of lysosomal enzymes is also unlikely to be the cause of RPED.
- Further research into the specific genetic and molecular mechanisms of RPED is warranted.