There are a number of causes of eye infections in cats, they can be caused by either a bacterial, virus or fungal infection. The type of infection relates to the part of the eye infected as well as the pathogen. Different parts of the eyeball and surrounding area can become infected or inflamed.
Types of eye infection:
Conjunctivitis– Inflammation or infection of the conjunctiva, the pink membrane which covers the front of the eyeball and inside the eyelids).
Uveitis – Inflammation or infection of the uvea (the pigmented vascular layer of the eye consisting of the iris, choroid, and the ciliary body).
Blepharitis-Inflammation or infection of the eyelid.
Stye – Infection of the sebaceous gland in the eyelid.
Keratitis – Inflammation or infection of the cornea.
Eye infections can affect one (unilateral) or both eyes (bilateral). Infections may be on their own or as a result of a more systemic illness such as Feline Herpesvirus or calicivirus (both causes of cat flu).
Conjunctivitis is the most common eye infection in cats. Injuries to the cornea resulting in scratches or ulcers can lead to an eye infection. Foreign objects such as a grass seed or an eyelash constantly rubbing on the surface damages the surface, which makes it more vulnerable to eye infections. It is also possible for a viral infection to be the primary cause of an eye infection, and as damage occurs for a secondary bacterial infection to take hold. Cats with weakened immune systems such as those with FIV are more prone to eye infections.
It is common for newborn kittens to develop eye infections early on, either due to the queen having a vaginal infection at the time of the birth or unclean surroundings. Kittens have very underdeveloped immune systems and are much more prone to developing infections than older cats. If you do have a litter of kittens, keep their surroundings clean and watch out for signs of infection.
Some cats will carry a viral infection (such as herpes) for the rest of his life and at times of stress, the virus will re-activate and cause symptoms.
Healthy cat eyes:
Before we go into symptoms of an eye infection, I will briefly outline what to look for in a normal cat eye.
A tiny bit of sleep in the corner of the eye is normal, but it should not be excessive (see below).
Normal sleep in a cat’s eyes.
The eye should be clear, with no signs of swelling in or surrounding the eye.
The pupils should be equal in size.
There should be no signs of cloudiness or swelling.
One of the most common symptoms of an eye infection is discharge and/or swelling. The type of eye discharge can give your veterinarian an indication as to the type of infection your cat has. If the discharge is thick and mucousy, it is indicative of a bacterial infection. Clear discharge is more likely to be viral in nature.
Other symptoms may also be present depending on the cause.
Redness and swelling may occur around the outer eyelid, the third eyelid or the conjunctiva
Raw, meaty appearance around the eye (this is a common sign of conjunctivitis)
Eye infections are serious and require urgent medical treatment. Left untreated eye infections can cause permanent blindness. Some eye infections, (such as conjunctivitis) are extremely contagious to other cats.
Your veterinarian will perform a thorough ophthalmic examination and make a diagnosis based on symptoms. Is one eye or both eyes affected? Is there discharge, if so, what is it like, is there any pain, redness, what about accompanying symptoms?
Baseline tests – Biochemical profile, complete blood count and urinalysis to evaluate the overall health of your cat.
Culture – If there is discharge from the eye, your veterinarian will perform a culture to determine the organism so that he can prescribe the most suitable type of antibiotic.
Fluorescein eye stain – Eye drops are placed in the eye to detect foreign bodies or corneal ulcers.
FIV and/or FeLV tests – If the cat suffers from recurrent eye infections as these viral infections cause immunosuppression, which makes the cat vulnerable to opportunistic infections.
If you suspect your cat has an eye infection, seek medical attention. Never use medications for humans on cats, and that includes eye drops.
Treatment will depend on the cause and/or the location of the infection.
Antibiotic ointment or drops for bacterial eye infections.
Anti-fungal medications for fungal infections.
Most viral eye infections are self-limiting and will go away on their own, however, your veterinarian may choose to prescribe topical anti-viral cream or drops if the cause is viral.
Wipe away any discharge with a damp cotton wool ball. Discard immediately.
A warm compress to relieve discomfort.
Your cat may have to wear an Elizabethan collar during treatment to avoid rubbing/damaging the eye.
Always wash your own hands after treating a cat’s eyes, it is possible for some infections to be transmitted to humans.
Keep bedding and food bowls clean at all times.
In addition to treating the eye infection, supportive care will be necessary to help your cat overcome feline herpes virus. This includes intravenous fluids to treat dehydration and oral antibiotics for a secondary bacterial infection.
If you have other cats in the household, watch out for signs of eye infection in them.