I chose one of the blood donor greyhounds from the vet school today to show a group of students what a normal canine retina looked like. But what did I find?
There’s a well demarcated area of tapetal hyper-reflectivity just by the optic nerve head (shown very dark as I had to reduce the exposure so the hyper-reflective area didn’t flood the camera with light) and also an apparently darkly pigmented area dorsolateral to the disc. Actually taking another photo from a slightly different angle (easy with my new digital fundus camera!) shows that area reflective and the other one near the disc dark. These are areas of post-inflammatory degenerate retinopathy which have probably been caused by Toxocara canis visceral larva migrans in this dog which was never wormed as a puppy. Although its very common in unwormed working dogs very little work has been published on this – the best paper is Hughes and coworkers on sheepdogs in New Zealand from way back in 1987 (Multifocal retinitis in New Zealand sheep dogs.
Veterinary Pathology 24:22-7. They found over a third of dogs with lesions.