Conjunctivitis in Cats


Conjunctivitis is a description rather than a disease – it is reddening or inflammation of the conjunctiva, which is the moist membrane that covers the eye and lines the eyelids. Normally it is clear and translucent with the blood vessels clearly visible underneath. The conjuctiva is a barrier for preventing foreign bodies from as large as grit and dust to as tiny as a virus penetrating the eye.

In conjunctivitis it becomes red and inflamed and weepy with either excess tears or some quite nasty-looking pus. Because it can be a symptom of something more systemic and serious, a cat with a ‘runny’ eye should always be taken to the vet.

Causes and Treatment of Conjunctivitis in Cats

There are many causes of conjunctivitis and as many treatments. It is not wise to try to treat a cat with a sore eye yourself, because the wrong treatment may have devastating results, even leading to the loss of the eye.

  • Viral infection. This is likely to be the herpes virus and the cat will remain prone to recurrence for life. Anti-virals are now quite specific and the vet will prescribe these, with possibly a long course of lysine, which has resulted in reduction of infections in some cases.
  • Respiratory tract infections. Treatment of the RTI is the first priority, with topical treatment with a bactericidal ointment if the eye is badly inflamed and to keep the infection under control.
  • Foreign bodies. These will be flushed out by the vet – it is unwise to try to do this yourself as you will probably stress the cat and may drive the foreign body, which may be sharp, deeper into the conjunctiva, causing a tear.
  • Environmental irritants. These should be identified and reduced or removed.
  • Corneal ulcers. These are quite common and can be caused by various problems, including environmental factors and immune problems. They will usually clear up by themselves, but an antibiotic will help prevent secondary infection.
  • Dry-eye. This can occur in some cats which have been bred to have certain facial features or spontaneously. Artificial tears can be applied or in some cases cyclosporine may increase tear production.
  • Allergies. Steroids to flood the eye may help, but if the allergen can be removed, this will be a permanent cure. 
  • Trauma. Treatment will depend on the nature of the injury.

Prevention of Conjunctivitis

Prevention of a condition with so many causes is all but impossible in most cases. If the cat has an allergy and it can be identified, it is sometimes practical to remove the cause. This is not always possible and so in that case it may be a matter of re-homing the cat for its own comfort. If environmental issues are present which are a physical irritant rather than an allergy, these may be able to be addressed. It is a good idea if the cat has conjunctivitis to avoid smoking when near it and also to look at the possibility of smoke, soot or other airborne particles from open fire being the cause.

Grass Seeds

These are difficult to eradicate but it should be possible to keep the cat away from them. Some cats are prone to getting grass seeds and similar garden irritants in their eyes, especially if they are avid hunters always poking their noses into vegetation. This is a case of ‘he’ll never learn’ and putting up with having to keep an eye irrigation bottle to hand and preferably getting some training from your vet on how to use it correctly. The wash in the bottle must be kept in date and scrupulously clean – once it is used it must be discarded, as there will be some contamination from the use as the wash sometimes floods back into the bottle. Without this basic precaution, an infection could be caused rather than alleviated by the use of the wash.

Signs of Conjunctivitis in your Cat

A sore eye is a very obvious thing and your cat will certainly let you know about it as it will be very painful. A slightly runny eye is a normal occurrence in some animals and in these cases it is important to watch that it is not worsening. Some cats will become severely photo-sensitive (unwilling to face the light) and may hide under a bed or in a dark place. Watch out for this and try to coax them out to check their eyes. Behavioural changes such as this is always worth a visit to the vet in any case. If your cat is unwell as well as having conjunctivitis, it is very important to get it to the vet as quickly as possible, as eye complications are very often part of an underlying condition which may be much more serious than a sore eye.

Can a Cat’s Conjunctivitis Spread to People?

When your cat has any illness it is good practice to wear gloves when handling and treating it. If this is impossible, then good hand washing hygiene is essential. This is not to say that ‘pink eye’ in cats will spread to people, but it is just a very good idea not to give a bacteria a chance. Even if it cannot jump species, it can easily travel on your hands or clothing or even in your hair to infect other animals by transfer. If your cat is unwell in any way, it is certainly an excellent plan not to let them go near children. Not only might they be carrying a bacterium, but they will also probably be grumpy and short tempered and a child will not always see or understand the classic signs of thrashing tail and flat ears and might get a nasty bite or scratch. If the cat’s eyes are affected and so it can’t see so well, this is even more likely.


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