What this means
Blood inside the eye shows as a red or dark red layer or patch behind the clear surface of the eye, sometimes seeming to fill part of the front of the eye. This is different from a red eye, where the white of the eye and the lining of the lids turn red. If you are not sure whether you are seeing blood inside the eye or only redness, the point is not to tell them apart yourself but to have the eye looked at by a vet.
Blood inside the eye can have very different causes: a blow to the eye or head, diseases of the structures inside the eye, raised pressure in the eye, inflammation, clotting disorders or other problems in the body. Sometimes it is linked to an inherited difference in how the eye formed, which can damage the retina. Which cause it is can only be decided by a vet who examines the eye, and there is no point waiting to see whether it passes.
Eye problems can threaten sight quickly, so every change matters. Do not put any drops in the eye or use home remedies, since without knowing the cause you can do harm. Your vet will find it useful to know when you saw the blood, whether the eye was injured, whether your dog can see or loses its bearings, whether both eyes are affected and, if you can, a photograph of the eye in natural light.
Possible causes
These are things that can cause this sign. It is not a diagnosis, and they are not equally likely for your dog.
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A blow or injury
After a blow to the eye or head, blood can collect inside the eye. Even when nothing shows on the outside, the eye may be damaged.
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An inherited difference in how the eye formed
Some breeds are born with a difference in the back of the eye that can allow blood to appear inside it. It can damage sight.
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Inflammation or raised pressure inside the eye
Inflammation or too much pressure in the eye can damage tiny blood vessels. It is painful and can quickly harm sight.
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A clotting disorder
When blood clots poorly, bleeding can appear in several places, including the eye. Other signs of bleeding are often seen too.
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A detached retina or another eye disease
When the retina is detached or damaged, blood can appear inside the eye and the dog can lose its sight.
What else to watch for
These observations help your vet build the picture faster. Note down what you saw and when.
- When you first noticed the blood and whether it is growing
- Whether the blood is in one eye or both
- Whether your dog can see: whether it bumps into things or misses a thrown toy
- Whether the eye hurts: squinting, rubbing the eye or avoiding light
- Whether the pupils are the same size
- Whether there is bleeding elsewhere, such as the gums, urine or stools
When to book a routine visit
Blood in the eye is a reason to see a vet the same day, as eye problems can threaten sight quickly. Put nothing in the eye and say when you first noticed the change.
Related conditions
Conditions whose entries mention this sign. The list is somewhere to read on, not a way to reach a diagnosis.
Body systems: Eyes