Disorders of the Conjunctiva in Cats
The conjunctiva is a thin membrane that lines the inside of the eyelids and extends over the white of the eye in the front portion of the eyeball. It plays a role in creating tears, providing protection for the eye from foreign invaders, eye movement, and healing of the cornea after injury. It is important to identify and treat problems of the conjunctiva, because some can indicate generalized disease, while others can lead to blindness if not treated.
Ruptured blood vessels beneath the conjunctiva may be the result of trauma, a blood disorder, or certain infectious diseases. This condition, by itself, does not require treatment, but close inspection is necessary to determine if more serious changes within the eye have occurred. If definite evidence or history of trauma is not present, then your veterinarian will perform a complete examination to determine the cause of the spontaneous bleeding.
Swelling of the conjunctival tissue around the cornea occurs to some degree with all cases of conjunctivitis, but the most dramatic examples are seen with trauma, a deficiency of proteins in the blood (hypoproteinemia), allergic reactions, and insect bites. Insect bites are treated with topical corticosteroids and usually heal rapidly. In other cases, specific therapy to treat the original cause is required.
Conjunctivitis, also known as pink eye, is inflammation of the conjunctiva. It is common in cats. It often occurs as the result of an infection with feline herpesvirus-1, which is extremely widespread among cats. Other causes include various bacterial infections, foreign objects, and environmental irritants. The signs are redness of the eye, swelling of the conjunctiva, discharge from the eye, and mild eye discomfort. The appearance of the conjunctiva usually is not enough, by itself, to allow your veterinarian to diagnose the cause with only a physical examination. A specific diagnosis often requires a medical history, a physical exam, tests on scrapings taken from the conjunctiva, Schirmer tear test, and occasionally biopsy.
Conjunctivitis in only one eye may result from a foreign object, inflammation of the tear sac, or dry eye. Conjunctivitis that starts in one eye and then spreads to the other, or that occurs in both eyes is commonly caused by infection with a virus or bacteria. It is common for cats that have a viral eye infection to then get a secondary bacterial infection. Environmental irritants and allergens are other common causes of conjunctivitis. If a mucus and pus-filled discharge is present, your veterinarian may prescribe a topical antibiotic. However, the antibiotic alone may not bring about healing if other factors are involved. Your veterinarian will also check for foreign objects, environmental irritants, parasites, and defects of eyelid shape, outline, or form, as these factors also contribute to pink eye. Because conjunctivitis can have multiple causes, your veterinarian may prescribe a combination of treatments, including antibiotic or antiviral therapy.
Conjunctivitis with large amounts of a thick discharge from the eye can occur in newborn kittens. It is usually the result of the same bacteria and viruses that cause infections in adult cats and is treated with topical antibiotics, such as an antibiotic eye ointment.
Also see professional content regarding the conjunctiva.