Rod-cone dysplasia in the collie

Area of Science:

• Ophthalmology
• Veterinary Genetics
• Animal Science

Background:

• Rod-cone dysplasia is a significant inherited ocular disorder affecting canine vision.
• Collie dogs are predisposed to specific forms of retinal degeneration.

Purpose of the Study:

• To characterize the clinical and electroretinographic features of rod-cone dysplasia in Collie dogs.
• To determine the inheritance pattern of rod-cone dysplasia in this breed.

Main Methods:

• Clinical ophthalmic examinations including fundic evaluation.
• Electroretinography (ERG) to assess retinal function.
• Pedigree analysis and selective breeding to establish inheritance patterns.

Main Results:

• Progressive vision loss, starting with night blindness at 6 weeks, progressing to severe blindness by 1 year.
• Clinical signs included tapetal hyper-reflectivity, attenuated retinal vessels, and optic nerve pallor by 6 months.
• Markedly reduced electroretinographic responses were detected as early as 16 days of age.

Conclusions:

• Rod-cone dysplasia in Collies presents with early-onset, progressive visual impairment.
• The condition is characterized by distinct clinical and functional retinal abnormalities.
• Selective breeding data strongly indicate a single recessive mode of inheritance for this disorder in Collies.