Browse our veterinary-reviewed Dog and Cat Illness Guide to learn more about pet health. Always talk to your veterinarian if you have a concern about your pet's symptoms or health.
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People have two eyelids. Your pet has a third protective eyelid at the inner corner of each of its eyes. This eyelid sweeps across the eyeball to moisten it or to remove dirt when needed.
Conjunctivitis is inflammation of the conjunctiva tissue that covers the eyeball and lines the eyelids and third eyelid. It can affect one eye or both.
The most common cause is bacterial or viral infections. Puppies can have an infection even before their eyes open.
Other causes include:
- Eye diseases (for example, glaucoma)
- Environmental and chemical irritants
- Dry eyes
- Trauma to the eye
- Genetic disposition
- Red eyes
- Swollen eye area
- Discharge from the eyes (cloudy tears, yellow or green mucus)
- Discharge from the nose
- Excessive blinking
- Bulging third eyelid
- Sneezing, coughing
Your veterinarian will first rule out other conditions like a foreign object in the eye, blocked tear duct, or glaucoma. Then, the veterinarian will likely do the following:
- Eye exam: close examination of the eyes, lids, lashes, tear ducts, third eyelid
- Schirmer tear test: paper strips inserted into the eye for a few minutes to measure tear production
- Corneal stain: a fluorescent dye is put in the eye and then studied with ultraviolet light to determine if the cornea (the outer covering of the eye) is damaged
- Blood tests: determines the underlying cause of the conjunctivitis
To treat conjunctivitis, it is essential to first determine the cause. Treatment may include:
- Topical medications: eye drops, ointments
- Systemic medications: antibiotics (oral or injections) or anti-inflammatory drugs
- Medication: to stimulate tear-production
- Surgery: for dogs with abnormal eyelids or eyelashes
Most pets respond quickly to medication. To avoid a relapse, it is important to give your pet the medications for as long as your veterinarian prescribes.
You can prevent relapses in a number of ways. Try to minimize stress to keep your dog on a nutritious diet with plenty of fluids. Your veterinarian may suggest that you vaccinate your dog against conditions that can cause conjunctivitis.
There is generally a great prognosis for conjunctivitis.
Occasionally, the underlying cause is not curable, but you can usually keep conjunctivitis in check, and your dog can live comfortably.
Medically Reviewed by Sara Ochoa, DVM