A form of progressive retinal atrophy (rcd2) in the Collie caused by an insertion mutation in the RD3 gene. It causes early degeneration of cones and rods with progressive vision loss from an early age. It is incurable and non-painful, and progresses to blindness.

rcd2 documented in the Collie. There are no reliable published figures for carrier frequency in the breed.

- Early and progressive night blindness\n- Photoreceptor degeneration (cones and rods)\n- Retinal atrophy on fundus examination\n- Progressive decrease in daytime vision progressing to blindness\n- No ocular pain

Rod-cone dysplasia type 2 (rcd2) was described as a clinical entity in the Collie. Kukekova et al. (2009) identified the insertion mutation in the canine homologue of the RD3 gene (formerly C1ORF36), establishing rcd2 as the orthologue of human and murine rd3.

- Test breeding animals before mating\n- Do not mate two carriers\n- Carrier × clear produces no affected animals; test offspring intended for breeding\n- Affected animals should not be bred\n- Preserve the genetic diversity of the breed

Differential diagnosis from other PRAs and acquired retinopathies. Early onset. There is no curative treatment; management of adaptation to vision loss.

Kukekova AV et al. 2009. Canine RD3 mutation establishes rod-cone dysplasia type 2 (rcd2) as ortholog of human and murine rd3. Mamm Genome. PMID: 19130129