Eye problems frequently pop up in pets and can range in severity from mild irritation to blinding pain. Red eyes, which are one of the most common issues, can be caused by a multitude of conditions. Identifying the reddened portion of your pet’s eye is key to determining the cause and administering the appropriate treatment. 

What are the types of red eyes in pets?

Redness in your pet’s eyes can be localized and classified as one of the following:

  • Episcleral injection — The sclera, or white portion of the eye, can appear red when its blood vessels become enlarged. Episcleral injection is typically caused by a disease process inside the eye.
  • Conjunctival hyperemia — The conjunctiva is a thin membrane that covers the sclera and the inside of the eyelids. Diseases outside the eye cause the blood vessels to swell in the conjunctiva, leading to conjunctival hyperemia.
  • Subconjunctival hemorrhage — Pools of redness that appear below the conjunctiva and deeper inside the eye are known as subconjunctival hemorrhage. This redness typically overtakes the entire sclera and is often caused by trauma, strangulation, or clotting disorders.
  • Hyphema — Hyphema is caused by a hemorrhage in the eye’s anterior chamber and can be seen as a red line in the eye, or complete redness.
  • Corneal neovascularization — If the cornea is injured, new blood vessels will form to help with healing and the eye will appear reddened.

What can make my pet’s eyes red?

The numerous causes of red eyes in pets can range greatly in severity. The most common reasons your pet’s eyes are red include:

  • Allergies — Although allergies in pets are more likely to cause skin issues, they can trigger ocular irritation. Environmental allergens, like pollen, weeds, and dust, are generally the culprits behind itchy, watery, reddened eyes.
  • Conjunctivitis — Conjunctivitis (i.e., inflammation of the conjunctiva) can be a primary or secondary condition. When the conjunctiva becomes inflamed, irritated, or infected, the eye and inner surface of the eyelids can appear red.
  • Corneal ulcer — Trauma, such as a nail scratch, or infections can cause sores on the eye’s outer surface. Without treatment, corneal ulcers can rapidly worsen and cause permanent damage.
  • Cherry eye — A prolapsed tear gland in the third eyelid can look like a cherry has popped up in the eye’s inner corner. This condition is common among certain breeds, and surgical correction is often needed to keep the gland in place.
  • Glaucoma — When pressure increases in the eye because of improper fluid filtration and drainage, glaucoma results. Your pet’s eyes can become red, bulging, and extremely painful.
  • Entropion — Eye irritation and redness can occur when your pet’s eyelids roll inward and rub against the cornea.
  • Keratoconjunctivitis sicca (KCS) — Also known as dry eye, KCS occurs when the tear glands do not function properly, typically resulting in eye irritation and a thick, “gooey” discharge that coats the eyes.
  • Foreign object — Debris can become trapped under the eyelid or stuck to the eye’s surface, irritating and inflaming the eye.
  • Uveitis — The uvea consists of three parts of the eye—the iris, ciliary body, and choroid. When any part is inflamed, severe pain and intense reddening of the visible part of the eye result. Uveitis has many causes, including infections, metabolic disease, hypertension, trauma, lens damage, or eye tumors.
  • Infectious diseases — Certain infectious diseases, including feline viral rhinotracheitis, feline calicivirus, and canine distemper, can cause eye issues that lead to reddened eyes.
  • Eye tumors — Masses growing behind or in your pet’s eye can increase intraocular pressure and also cause a red eye.

How will my veterinarian diagnose the cause of my pet’s red eyes?

Our Stanton Pet Hospital veterinarian will discuss your pet’s medical history and the signs you’ve seen at home, and perform a standard physical and a comprehensive ocular exam. Your pet may also require a series of diagnostic tests to determine the cause of their red eyes.

Diagnostic tests will include blood work, urinalysis, and a blood pressure check to look for underlying diseases. Based on their clinical signs, your pet may require special eye tests that may include:

  • Schirmer tear test — A small strip is held against your pet’s eye to measure tear production.
  • Fluorescein stain — A pet-safe dye is dripped into your pet’s eye to check for scratches, ulcers, or other corneal damage. Stain uptake indicates an injury.
  • Tonometry — A tonometer is a special tool used to measure intraocular pressure.

How do I treat my pet’s red eyes?

Treatment for your pet’s red eyes will depend on the underlying cause and may require multiple or lifelong therapies to be successfully cured or managed.

Treatment for red eyes in pets may include:

  • Topical medications — Eye drops and ointments can provide pain relief and also treat infections and poor tear production. Many ocular conditions require treatment with multiple topical medications.
  • Oral medications — Oral pain-relieving medications, in addition to systemic antibiotics, may be necessary to manage your pet’s discomfort and treat infections.
  • Surgery — Surgery is the only treatment for some red-eye conditions. For example, for cherry eye, the prolapsed gland must be tacked back into place surgically, while entropion repair requires removal of excess eyelid tissue that is rolling in.

If your pet has developed a red eye, don’t wait to see if the condition improves on its own. Give our Stanton Pet Hospital team a call to schedule an appointment, or request one online.