Normally dogs’ eyes are clear, bright and usually have only a clear, watery discharge, but some breeds with normal eyes may accumulate a light gray material on the corners of their eyes. You can just clean these off with clean cotton swabs. If your dog’s eyes are red (inflamed) and/or have significant accumulations of yellowish or greenish material, it could indicate conjunctivitis, inflammation of the conjunctival membranes. The conjunctiva, are light pink membranes that cover the front of the eyeball and the inside of the eyelids. Conjunctivitis can be a problem in one eye (unilateral) or both eyes (bilateral) and can be chronic, infectious or non-infectious. Other signs of conjunctivitis include swollen eyelids, pawing or rubbing at the eyes, excessive blinking, squinting, and protrusion of the third eyelid, also known as the nictitating membrane, usually seen as a reddish mass extending over part of the eye from the inner corner.
In this area, allergies to pollen, dust and mold are a major cause of conjunctivitis in dogs. Other causes include viral infections such as canine distemper, bacterial infections, especially from Staphylococci and Streptococci. A lack of tears can result in keratoconjunctivitis sicca or dry eye. This is an inflammation of both the cornea and the conjunctiva and can be caused by trauma, inflammation of the conjunctival glands and ducts and/or scarring of these structures. Dry eye can also be the result of certain immune diseases or diabetes mellitus. Foreign objects such as grass seeds, hair, and eyelashes can result in conjunctivitis as can injury, some parasites, fungal infections, tumors and certain anatomical abnormalities. Sometimes we just cannot determine a cause, and assign the name idiopathic conjunctivitis.
Follicular, also known as mucoid, conjunctivitis occurs when the small mucous glands (follicles) on the underside of the third eyelid react to an irritant or infection and change to a raised, rough surface that irritates the eye further and produces a thick off colored mucous discharge. Sometimes even after the initiating cause has been removed this thickened follicles persist and may require surgical treatment. Purulent conjunctivitis is a serious form of conjunctivitis characterized by secondary bacterial contamination and requires veterinary diagnosis and prescribed treatment.
Your veterinarian can diagnose dry eye by using the Schirmer Tear Test. The treatment does require that you continue to treat the condition throughout the dog’s life. The treatment of purulent conjunctivitis requires a proper diagnosis by your veterinarian who will instruct you about safely removing mucous and pus from the dog’s eyes as well as any pus and crust that may adhere to the eyelids. Your veterinarian will also prescribe an appropriate antibiotic ointment or drops to use as directed. Conjunctivitis from allergies, but not complicated by a bacterial infection, may be treated with drops or ointments containing corticosteroids but these should not be used if there is a corneal ulcer or injury because the corticosteroids prevent the local inflammatory response that helps fight the infection. Your veterinarian may find it necessary to do culture and sensitivity testing to determine the most appropriate treatment. If your veterinarian suspects injury to the cornea s(he) may apply a dye (fluorescein) to the eyeball that stains and demonstrates scratches or ulcers. Antiviral eye medications are available to treat viral conjunctivitis and L-Lysine may be beneficial in some cases. Anti-fungal medications are available for fungal eye infections.