Unless they’re a frequent flyer dealing with early-morning business meetings, red eyes aren’t something dogs—or cats—should normally experience.
Seeing redness in your pet’s eye can be alarming for pet owners. While mild irritation may sometimes be temporary, red eyes can also signal a more serious condition that requires prompt veterinary attention.
“Eyes are delicate, and problems can worsen quite quickly,” says Dr. Lois Palin, VMD, of Doylestown Veterinary Hospital. “It’s always important to know when to seek help.”
Common Reasons Your Dog’s Eye May Be Red
According to Dr. Palin, several conditions can cause redness in a dog or cat’s eye. Understanding the possible causes can help pet owners recognize when veterinary care may be needed.
Irritation or Environmental Factors
Environmental irritants such as dust, pollen, smoke, or debris can cause eye redness.
“Dogs who ride in cars with their heads out the window, or are in wooded, grassy areas, may develop redness just due to environmental exposure,” Dr. Palin says.
Allergies
Just like humans, pets can experience allergies—both seasonal and year-round. Allergies can cause symptoms such as:
- Red or watery eyes.
- Squinting.
- Rubbing at the eyes.
“Usually with allergies, we see that both eyes are affected,” says Dr. Palin. “There can also be other signs like itchy skin and ears. Not always, but often.”
Conjunctivitis (Pink Eye)
Commonly known as “pink eye,” conjunctivitis is inflammation of the tissue lining the eyelids.
It can be caused by infection or allergies and may include symptoms such as:
- Eye redness.
- Discharge.
- Squinting.
- Swelling around the eye.
“Pet parents would typically notice redness,” Dr. Palin says. “Usually, there is going to be some discharge, squinting, and maybe even some swelling around the eyes.”
Injuries or Trauma
Eye injuries can occur if a dog scratches their cornea or gets a foreign object stuck in the eye. Blunt trauma may also cause redness, discomfort, and squinting.
Pets experiencing trauma may also try to rub their eyes frequently.
Corneal Ulcers
“A corneal ulcer is basically like an open sore on the cornea, the eye’s surface, and they can be quite painful,” Dr. Palin says.
Common symptoms include:
- Redness.
- Excessive tearing.
- Squinting.
- Sensitivity to light.
Because corneal ulcers can worsen quickly, prompt veterinary care is essential.
Glaucoma
Glaucoma occurs when pressure builds inside the eye and can lead to blindness if untreated. The condition is extremely painful.
Signs may include:
- Red eyes.
- Cloudiness.
- Enlarged eye appearance.
“This is certainly a condition that requires urgent veterinary care,” Dr. Palin stresses.
Cherry Eye
“There is a little gland associated with the third eyelid, which is on the inside corner of a dog’s eye,” explains Dr. Palin.
When this gland becomes displaced, it can appear as a pink or red swelling in the corner of the eye.
“It is not always painful, but it does require veterinary care. Often, surgery is needed to correct it.”
Signs Your Pet Needs Immediate Veterinary Care
If you notice redness in your dog’s eye, monitor them closely for additional symptoms. Dr. Palin recommends seeking veterinary care right away if you notice:
- Squinting or keeping the eye closed.
- Rubbing or pawing at the eye.
- Any discharge, especially yellow or green.
- Cloudiness or color changes in the eye.
- Swelling around the eye.
- Sensitivity to light.
- Sudden redness.
- Signs of pain or vision changes.
Why Prompt Veterinary Care Matters
Eye conditions can progress rapidly and may lead to permanent damage or vision loss if not treated promptly.
One challenge is that many eye problems look similar but require completely different treatments.
“It’s important to have a veterinarian evaluate your pet’s eye in order to recommend appropriate care,” Dr. Palin says.
Pet owners should also avoid trying home remedies or using leftover medications.
“It is so important that owners never use leftover or human eye medications on their pets,” Dr. Palin warns. “This can certainly make things worse.”
When in Doubt, Call the Pros
If your dog’s eye looks red or irritated and you’re unsure what’s causing it, the safest step is to contact your family veterinarian.
Early evaluation and treatment are the best ways to prevent complications and protect your pet’s vision—while getting a clear answer to the nagging question: why is my dog’s eye red?
“When in doubt, get them checked.”
