This easy-to-spy problem is common in both cats and dogs and can be caused by an injury, an irritation or even a disease. Regardless of the cause, your pet’s eye may look roughly the same: Some or all of the structures surrounding the eye will be red and/or visibly swollen, a condition commonly known as conjunctivitis.

Additional signs associated with conjunctivitis include clear, grayish, whitish, greenish or even reddish discharge; red and swollen eyelids; cloudiness of the cornea (the clear covering of the eye, which may appear bluish or hazy); redness of the whites of the eyes, rubbing or pawing of the eyes to relieve itching; and repetitive blinking, squinting or closing of the eyes, which usually indicates pain. Take special note of these symptoms, because they can help a veterinarian determine the cause for eye redness and irritation.

Causes of Red and Irritated Eyes

When a dog or cat goes to the vet with red and irritated eyes, here are a few of the typical causes:

Trauma: Nothing creates redness and irritation as quickly as a poke to the eye by a branch or some other foreign object. Even if the eye itself is unharmed, the surrounding tissues can become inflamed.

Environmental irritants: Cigarette smoke, dirt, dust and other irritants can cause periocular irritation in cats and dogs.

Bacterial conjunctivitis: This is relatively uncommon as the primary cause of conjunctivitis in dogs and cats, but it can occur.  More often, bacterial conjunctivitis occurs when the eyes are already inflamed from another condition, like dry eye or viral conjunctivitis.

Viral conjunctivitis: This form of conjunctivitis is especially common in pets diagnosed with canine distemper, FIV (feline immunodeficiency virus), FeLV (feline leukemia virus) or one of the feline respiratory viruses (like feline herpesvirus).

Corneal disease: Diseases of the cornea — the clear covering of the eyeball — can result in corneal inflammation, as well as periocular swelling. 

Other Eye Diseases: Although corneal problems are the more common culprits of eye redness and swelling, other eye diseases can produce similar symptoms, including glaucoma.

Skin diseases: Mange mite infestation, painful or irritating cancers, and other skin conditions that occur around the eyes can cause rubbing, itching, swelling and other problems in the eye area.

Systemic diseases: Some systemic illnesses (conditions that affect the whole body) like leptospirosis and Rocky Mountain spotted fever can cause conjunctivitis.

What Your Veterinarian Will Do

Here are some of the things your vet may do if your pet has red or irritated eyes.

1. Take a history. Most veterinarians will begin by asking a few basic questions to help them understand the history of the problem. When did you first notice the redness and irritation? Has it changed? How has your pet been acting? What medications have you used? (If your pet has taken any kind of medicine, bring it with you.)

Step 2: Do a physical evaluation. Examining the entire body, not just the eyes, is a crucial part of the process.

Step 3: Do an ophthalmic evaluation. An ocular examination of all visible internal and external eye structures is essential. A test to determine eye dryness (Schirmer tear test) and/or a corneal stain to identify the presence of possible erosions or ulcers might be in order. Depending on the veterinarian’s skill set and available equipment, you may need to schedule a follow-up visit with a veterinary ophthalmologist.

Step 4: Do a dermatologic evaluation. Your veterinarian may also look for the presence of skin lesions, which may point to trauma, cancer or other disease.

Step 5: Order laboratory tests. A blood and urine test may be useful. Aside from a basic urinalysis and a CBC and chemistry panel, your vet may order other specific tests to help identify particular diseases, such as FIV, FeLV and canine distemper.


Depending on the underlying cause, treatment can range from a topical anti-inflammatory or antibiotic medication, to lubricating over-the-counter eye drops to surgery and long-term eye medication.

What You Can Do at Home

Any pet who suffers from red and irritated eyes should visit a veterinarian as soon as possible, but if you can’t schedule an immediate appointment, there are some measures you can take to keep your pet comfortable in the meantime.

Prevent pawing and scratching: To keep pets from further aggravating the inflammation, buy a soft E-collar or try to place socks on their feet.

Clean the area: Excessive discharge can be wiped with warm water and a tissue, but try to avoid actually touching the surface of the eye. A cool compress with a damp cloth can also be soothing. Never put any medication into the eyes unless directed by your veterinarian. 

Monitor symptoms: If your pet exhibits other unusual symptoms, such as fever, poor appetite and lethargy, head for your vet or an animal hospital right away. And know that eye pain — the key signs are frequent blinking or closing of the eyes, aggressive rubbing or pawing — means your pet needs emergency care.

This article was written by a Veterinarian.