If your cat has a sore or red eye, or there is discharge from the eye, then it is important to contact your vet. Your cat may have an infection in the eye, but a discharge can also be caused by a foreign body (such as a grass seed) caught under the eyelid. It is important that diseases of the eye are treated quickly to prevent any permanent damage being done.
The conjunctiva is the pinkish surface surrounding the eyeball. The third eyelid is an extra protective eyelid in the cat and is also covered by conjunctiva. In normal cats the conjunctiva is not readily visible. In conjunctivitis this membrane is inflamed and becomes red and swollen. Conjunctivitis can affect one or both eyes.
Cats with conjunctivitis usually have a discharge from their eye(s). This can be clear and watery or thick and greeny/yellow in colour. The conjunctiva is often more visible and may be swollen, partially covering the eye. The eye(s) may be held half closed and the third eyelid is more prominent.
A number of different conditions will cause conjunctivitis. Many are sudden in onset and easily treatable. Others cause a long term disease which can be more difficult to control.
- Irritants, trauma (e.g. cat fights) and foreign bodies (e.g. grass seeds) can cause conjunctivitis. In most cases treatment is rapidly effective once the cause has been removed.
- The most common causes of conjunctivitis in cats are infectious agents. These can be viruses (usually one of the cat flu viruses), bacteria and a group of organisms which resemble bacteria (most commonly Chlamydia).
- Disease of the immune system can also cause conjunctivitis. These diseases are rare in cats but can be difficult to treat.
Usually your vet will be able to tell that your cat has conjunctivitis by a simple examination. They will want to examine the eye closely to ensure there is no damage nor foreign body. If there is no obvious traumatic cause most cases will respond to drops or ointment containing antibiotics and anti-inflammatory drugs. If a foreign body is present then this obviously needs to be removed.
If the signs are not getting better with a few days treatment, or appear to improve only to get worse again when treatment stops, more investigation is required. Your vet will want to take a swab from the conjunctiva to look for infection. In some cases a blood sample may also be required.
If there is no infection then it can be helpful to look at a sample of cells from the conjunctiva. This sample is obtained by gently scraping the surface of the conjunctiva with a cotton wool swab or spatula. If a larger sample is required, then a section of conjunctiva taken surgically may be necessary.
In most cases conjunctivitis is treated by application of drops or ointments to the eye. Sometimes with particularly stubborn infections antibiotic treatment may also need to be given by injection or tablet.
If you are able to treat your cat’s eyes this can be done at home but regular treatment is essential. Most drops or ointments need to be administered at least 3-6 times a day. Two people are usually required to give drops to a cat, one to hold them still and the other to give the treatment. If you have any doubts as to how to give the medication prescribed, please ask your veterinary practice to give a demonstration. If you are unable to treat your cat appropriately your vet may arrange to keep it in the hospital for a few days to ensure that effective treatment is given.