Wee “Hobbit” was a sweet, three-year-old Persian cat. She had been brought into the surgery frequently recently with recurrent, painful sore eyes and conjunctivitis symptoms. She was becoming increasingly grumpy, and she was clearly fed up with her Vet visits and all her topical eye treatments.
Conjunctivitis is an inflammation of the conjunctiva of the eyes. The conjunctiva is a mucous membrane layer of epithelial cells with
mucus-secreting cells covering the eyeball lining the eyelids. Cats also have a third eyelid, or nictitating membrane, in the inner corner of each eye, also covered by conjunctiva. In healthy cats, the conjunctiva of the eyelids is not readily visible and has a pale, pink colour. When conjunctivitis occurs, the conjunctival membranes become red and swollen and this can affect one or both eyes.
Signs of conjunctivitis are: Reddened conjunctival membranes; Excessive “tearing” or "weeping" from one or both eyes; An abnormal yellow, or greenish discharge; “Squinting”, keeping their eyes closed and blinking frequently; Swollen conjunctival tissues and the third eyelid partially or fully covering the eye; Scratching and rubbing at the eyes to the point of inflicting further trauma to these delicate tissues.
The most common causes of conjunctivitis can be roughly divided into two categories: infectious diseases and non-infectious conditions including allergies, hereditary conditions, and tumours. Conjunctivitis may also be a secondary symptom of another concurrent disease.
Conjunctivitis in cats is typically due to infection and is more often caused by a viral infection. While cats of any age can be affected, conjunctivitis is most common in younger cats especially kittens less than a year old. There seems to be a higher prevalence of chronic conjunctivitis in pure-bred cats, and in those breeds with flat faces and shortened noses, such as Persians and Himalayans. It is also more common in cats who are immunocompromised with feline immunodeficiency virus or feline leukaemia virus.
In many cases, viruses, such as feline herpesvirus, or feline calicivirus are an initial cause of upper respiratory infections with conjunctivitis symptoms. Primary viral infections are often complicated by secondary bacterial infections with a variety of bacteria, including Streptococci and Staphylococci. Two other organisms, Chlamydophila Felis and Mycoplasma are bacterial organisms that are also capable of causing respiratory infections and conjunctivitis symptoms.
There are also non-infectious causes of conjunctivitis. Breeds such as Persians, Himalayans may be born with a hereditary turning-in of the eyelids, called Entropion. Entropion causes corneal irritation when the eyelashes constantly rub against the eyeball. Foreign bodies, such as dust or sand, may cause irritation, or an exposure to irritant chemicals may initiate a conjunctivitis that can then lead to a secondary infection. Allergies can also be a cause of conjunctivitis; allergic conjunctivitis can be caused by a variety of environmental allergens such as dust, airborne chemicals, and certain plants. However, specific allergens are difficult to identify and avoid. Conjunctivitis can also be a symptom of eye tumours.
During an initial examination, a tentative diagnosis of conjunctivitis can made after ruling out any initial obvious causes of eye irritation e.g. a foreign body in the eye, a corneal ulcer, or another injury to the eye. The general approach to a non-specific conjunctivitis is to use topical preparations initially to control the secondary bacterial infection, and anti-inflammatory drugs to reduce the inflammation. Most cases will resolve with treatments within five to fourteen days. For cases that are not resolving with advised treatments, or are recurrent, further investigations are advised. A referral to a Veterinary Ophthalmologist may be advised for a full Ophthalmic examination and further tests, to try to reach a more definitive diagnosis. When a definitive diagnosis has been reached, more specific tailored treatment regimens can then be used.
The prognosis for conjunctivitis depends on the specific diagnosis. Good compliance and regular, frequent topical treatments are often essential in successfully treating this problem. Most eye drops need to be administered from three to six times a day at the start of treatment. With cats however, this can be difficult, and two people may be necessary, wrapping your cat in a large towel or blanket can assist.
“Hobbit” was referred to the Veterinary Ophthalmologist and it was confirmed that she did have Herpes viral conjunctivitis. This meant that she would need on-going tailored treatments and regular eye check-ups to deal with any flare ups.
Wee “Hobbit” did respond extremely well though to her treatments, and she was soon back to her happy, amiable self again. She would now come to her owner for her eye drops, and she seemed to know that her new treatments helped her.
If you are concerned about conjunctivitis symptoms with your cat, please do contact your Vet practice for an initial check-up.