Red eyes are uncomfortable for pets and alarming for pet owners. If your pet’s eyes are suddenly inflamed, that could signal an underlying irritant or medical condition. 

Eye problems can escalate quickly and some are true emergencies. Review the following common red-eye causes in pets and contact your nearest Neighborhood Veterinary Centers location if you need to schedule an appointment.

Your pet has allergies

Airborne allergens, such as grass and tree pollen, mold, and dust, can irritate your pet’s eyes, creating visible inflammation and vasodilation (i.e., enlarged vessels) on the eye white and the conjunctiva (i.e., eye lining). One or both eyes may show increased clear or discolored discharge.

Environmental allergies can be seasonal or year-round and are often accompanied by other signs, such as generalized itchiness (i.e., atopy), recurring ear infections, or less commonly, respiratory signs, such as sneezing and coughing.

Your pet has a bacterial or viral infection 

Conjunctivitis (i.e., inflammation of the eye’s clear outer layer and inner eyelid) occurs secondary to a bacterial or viral infection. Pets may become infected through close contact with another pet, or because they have a preexisting eye injury, such as ulceration, foreign object, or ingrown eyelashes (i.e., entropion).

Pets with conjunctivitis may squint or seem light- or close-movement-sensitive. Yellow, white, or green discharge may also be seen from one or both eyes.

Your pet has a corneal ulceration

Ulcerations are scratches or wounds on the eye’s surface. Corneal ulcerations can have numerous causes, including environmental irritants (e.g., grasses, seeds, allergens), inadequate tear production, eye abnormalities (e.g., inward-facing eyelashes, distichia), infection, or traumatic injury (e.g., cat scratch, persistent facial rubbing). Pets with endocrine diseases such as diabetes and thyroid disease can be predisposed to corneal ulcers.

Corneal ulcers are painful and pets may rub or paw at their eye trying to relieve their discomfort, which may worsen their condition.

Your pet has a foreign object in their eye

Pets who ride in open vehicles or like to stick their heads in tall grasses are at risk for foreign object injuries. Debris (e.g., gravel dust, dirt, hair, grass blades, seeds) can become trapped against the eye or along the lid, where they create friction and irritation. 

You may be able to gently flush away any eye debris that you can see with a saline eye wash. Monitor the eye for further redness or discharge, which may indicate an unseen injury or ulceration.

Your pet has a prolapsed third eyelid (i.e., cherry eye)

Dogs and cats have a third eyelid (i.e., nictitating membrane) in the inner corner of the eye that is attached to a gland and aids in tear production. When the ligament holding the gland is weak, the gland and third eyelid protrude in the eye as a red or pink mass. The third eyelid also can appear in cats who are stressed or ill. 

Pets with persistent third eyelid prolapse generally require surgery that involves suturing the gland in the correct position.

Your dog has glaucoma

In a healthy eye, appropriate intraocular pressure is maintained by balancing fluid in and out of the eye. In pets with glaucoma, this careful balance is disrupted and pressure steadily increases, resulting in permanent and irreversible damage to the retina and optic nerve, and rapid vision loss in one or both eyes. 

Despite the availability of medical treatment that can slow disease progression and control pain, glaucoma management is challenging, and many pet owners opt for surgical enucleation (i.e., eye removal). 

Your dog has dry eye

Like humans, dogs can experience inadequate tear production that can result in chronically dry eyes (i.e., keratoconjunctivitis sicca), which may be inherited or secondary to an ocular condition or injury (e.g., cherry eye or infection). 

Certain breeds are more likely to experience KCS, including those with prominent eyes, such as the bulldog, pug, Lhasa apso, shih tzu, and Cavalier King Charles spaniel.

Is my pet’s red eye an emergency?

Eye conditions do not get better without treatment and may compromise your pet’s vision. If your pet’s eyes are red, irritated, or otherwise abnormal in appearance, contact your nearest Neighborhood Veterinary Centers location.