Being a keen proto-ophthalmologist you tend to look closely at the eyes of normal dogs coming for routine vaccination. In this Collie-cross dog you see this retinal abnormality. What is it and what does it mean?
The image shows an abnormaly large solitary choroidal vessel characteristic of choroidal hypoplasia in collie eye anomaly. While the condition can occur in dogs other than collies (Rampazzo et al Collie eye anomaly in a mixed-breed dog. Veterinary Ophthalmology 2005 8:357-60, Bedford Collie eye anomaly in the Lancashire heeler.
Vet Rec. 1998 143:354-6) it still remains pretty anomalous, even given teh linkage analysis by Gus Aguirre and Greg Acland’s group (Lowe et al Linkage mapping of the primary disease locus for collie eye anomaly. Genomics. 2003 8:86-95) which showed the gene for choroidal hypoplasia (but not optic nerve coloboma shown here) to be located on chromosome 37, homologous with human 2q35. This is an interesting location as it may be associated with the PAX 3 gene, key in development and mutated in human Waardenburg type 1 syndrome. Does that make it sound less anomalous? Probably not!