Why do dogs' eyes turn red? - briefly
Dogs' eyes can turn red due to various reasons, including increased blood flow to the eye or inflammation of the vessels in the sclera (the white part of the eye). This condition is often temporary and may resolve on its own, but if it persists, veterinary attention should be sought.
Why do dogs' eyes turn red? - in detail
Dogs' eyes can turn red due to several reasons, each with distinct causes and manifestations. The most common cause is a condition known as cherry eye, which results from the prolapse of the third eyelid gland. This gland, also called the nictitating membrane, is responsible for producing tears that keep the eye lubricated. When it protrudes, it appears red and swollen, giving the appearance of a cherry in the corner of the dog's eye. Cherry eye can occur due to genetic predisposition or trauma, and it is more common in certain breeds like Cocker Spaniels, Beagles, and Bulldogs.
Another reason for red eyes in dogs is conjunctivitis, an inflammation of the conjunctiva, the thin layer of tissue that lines the eyelids and covers the white part of the eye. Conjunctivitis can be caused by allergies, infections (bacterial or viral), or irritants like dust or smoke. Symptoms include redness, swelling, discharge, and squinting. In some cases, conjunctivitis can be contagious, so prompt veterinary care is essential to prevent spread to other animals or humans.
Dry eye syndrome, also known as keratoconjunctivitis sicca (KCS), is another possible cause of red eyes in dogs. This condition occurs when the tear glands do not produce enough tears to keep the eye adequately lubricated, leading to inflammation and irritation of the conjunctiva. Dry eye syndrome can be caused by an autoimmune disorder or damage to the tear glands from certain medications or illnesses. Symptoms include redness, squinting, pawing at the eyes, and a thick, mucoid discharge.
In addition to these common causes, red eyes in dogs can also be a sign of more serious conditions such as glaucoma, uveitis, or corneal ulcers. Glaucoma is an increase in intraocular pressure that can cause redness, pain, and vision loss if left untreated. Uveitis is inflammation of the uveal tract, which includes the iris, ciliary body, and choroid. Corneal ulcers are open sores on the surface of the eye, often caused by trauma or infection.
If your dog's eyes turn red, it is crucial to consult with a veterinarian promptly. The veterinarian will perform a thorough examination, including tests such as the Schirmer Tear Test (STT) to measure tear production and tonometry to assess intraocular pressure. Based on the findings, appropriate treatment can be initiated, which may include medication, surgery, or lifestyle changes. Early diagnosis and intervention are key to preserving your dog's vision and preventing further complications.