Hypertensive retinopathy in a dog

By Emma Scurrell

A 9-year-old Greyhound with a history of chronic renal disease presented with acute, unilateral hyphaema. Repeated bouts of intraocular haemorrhage occurred and enucleation was performed following the development of secondary glaucoma.

Fig 1. There is abundant intraocular haemorrhage whereby blood fills both the anterior chamber and vitreous. Note that the retina is completely detached bar its attachment at the optic nerve head and peripherally at the ora serrata (a butterfly retinal detachment).
Fig 2. This is a H&E section of a different dog’s retina to demonstrate what a normal retinal arteriole looks like.
Fig. 3 This is a H&E section of the detached retina from this case in which two retinal arterioles are evident. The walls of both arterioles are diffusely expanded by a bright pink homogeneous matrix, albeit to a much greater degree in the top right arteriole. This is what is known as hyalinisation and it results from the leakage of plasma products into the vessel wall secondary to endothelial damage. In the bottom left arteriole, haemorrhage dissects within the wall (intramural haemorrhage).
Fig 4. A similar change is present within this choroidal arteriole. Note how the thickening of the wall has resulted in extreme narrowing of the blood vessel lumen that is now barely visible. This degree of narrowing could result in ischaemic injury.

Final diagnosis

Retinal and choroidal hyalinising arteriolosclerosis associated with intraocular haemorrhage characteristic of hypertensive retinopathy

Discussion

Dogs and cats suffering from systemic hypertension may present with blindness due to hypertensive retinopathy. This condition is often associated with retinal haemorrhage, retinal detachment and hyphaema and can eventually result in glaucoma. In fact, hypertensive retinopathy is one of the leading causes of blindness in older cats.

The potential causes of systemic hypertension are numerous but chronic renal failure (CRF) is one of the most common underlying causes and at least 60% of dogs with CRF are hypertensive. A persistently elevated systolic blood pressure was confirmed in this case.