This cat is presented emaciated at a charity clinic. It has been rescued from a ramshackle farm where the numerous dogs and cats there are fed the same cheap commercial dog food. What is this retinal lesion and can you explain why the cat is suffering from it?
This is a focal area of retinal degeneration dorolateral to the optic disc. This is the area centralis, a region of highly concentrated photoreceptors with consequently a high energy demand. The retinal degeneration is most likely here to be caused by taurine deficiency. Cats require this amino acid while dogs do not, thus a cat fed on a dog food diet will develop lesions such as this retinopathy and cardiomyopathy. The condition was first identified more than a quarter of a century ago (Hayes et al Retinal degeneration associated with taurine deficiency in the cat.
Science. 1975 188:949-51).