I was asked to look at this black labrador as he was extremely hypertensive with a suspected phaeochromocytoma. I thought I might see the same sort of retinal changes as we detect in a cat, though to my mind they occur much less frequently in hypertensive dogs. But what should I see but this?! What do you reckon it is and what would you do next?
I don’t think there is much of a differential list here – this is a spot diagnosis and a big black spot one at that! Choroidal melanomas are rare in dogs but look just like this and I can’t think of anything else that does though this is my first one in 25 years of ophthalmology! An ultrasound scan shows that the tumour doesn’t invade much further than the choroid. While the few papers in the literature on the tumour in dogs do document metastasis, this is generally late on in tumours that were much more advanced when dioagnosed than this one.
Sorry that this isn’t the best ultrasound scan in the world but shows the ‘collar stud’ appearance classic of these neoplasms. Note that there is a flat retinal detachment visible on the scan and numerous small bullae of detachment classic of hypertensive retinopathy around the tumour and further afield on the retinal photo. They occur in the otherwise normal fellow eye below, baving said that this is much less severe than a feline hypertensive retinopathy at a similar blood pressure of nearly 300mmHg. If you can explain why cats and dogs are so different in this regard do please tell!!