What Does It Mean When Your Dog Has Red Eyes?


A few years ago, my Leroy had a bit of an eye irritation, and a friend said, “Ohmigod, your dog has red eyes, and that means he’s schizophrenic; you’ better have him put to sleep before he hurts someone!”

Well, I knew better I don’t even know where this “urban myth” about dogs with red eyes came from, but I knew it wasn’t true. There were many possible reasons for Leroy’s red eyes, but mental illness definitely wasn’t one of them!

So, what does it mean if your dog has red eyes? Usually, it means that he has an allergy, or a physical illness. Some cases of red eye in dogs are easily identified and treated. Others might be a bit more problematic. So, let’s take a look at the reasons why your dog has red eyes, and what you can do about it.

What Causes Your Dog to Have Red Eyes?

There can be any number of reasons why your dog might have red eyes. It could be an irritation of the eye, or even a disease elsewhere in the dog’s body that could affect the eyes. The main thing to keep in mind is that any kind of inflammation or redness in your dog’s eyes could lead to blindness.

If your dog has red eyes, it could be due to inflammation, and it might also be accompanied by watering or discharge. If you notice that your dog’s eyes have been red for over 24 hours, then a visit to the veterinarian is in order. Other symptoms could include pawing at the eye, a red mass under the eyelid, white or red spots in the eye, or puffiness and swelling in the eye area.

Allergies and Other Conditions

Often, a dog has red eyes due to allergies. This could be due to contaminants like pollen, dust or weeds. Another common condition is conjunctivitis, which is an irritation of the eye that could also be connected to allergens. Kerataconjunctivitis is a condition where the eye becomes abnormally dry because not enough tears are produced. Another condition is entropion, which occurs when the dog’s eyelid turns inward, and the lashes irritate the eyeball.

Other conditions include Cherry Eye, which is a condition in which a gland is inflamed, and juts out from the eyeball – it looks like a little red bump underneath the eye. Hyphemia is another condition, in which a foreign body becomes trapped in the eyes and irritates it. Corneal ulcers can occur when a sore develops on the cornea due to infection.

One of the most frightening eye conditions that can become apparent when your dog has red eyes is cancer. Not all masses that grow behind the eye are malignant, but some are, and if you suspect a mass under the eyelid, you need to take your dog to the vet right away. Most commonly, the reasons why your dog has red eyes will be fairly innocent, but you just can’t take the chance.

Eye Examinations

When your dog has red eyes, your veterinarian will want to do a thorough examination. He or she wants to know when the redness started, how long it’s been going on, and any other behaviors that might indicate a problem. An ophthalmologic examination involves looking in detail at your dog’s eyes, examining the retina, the tear ducts, the corneas and the eyelids.Your vet will look at areas that might have been damaged, and also at the underlying tissues that could be causing redness in your dog’s eyes.


Treatment will depend on the diagnosis. Often, things that affect your dog’ eyes might not immediately appear in the eye area. Eye problems can be due to kidney and liver disorders, electrolyte imbalances, and improper hydration.

If the problem is actually in the eye, then treatment will probably take the form of topical medications – eye drops or ointments that you will administer until the condition is ease. Sometimes, antibiotics might be needed. If your dog has red eyes due to an underlying disease, then other medications might be needed. Sometimes (although rarely) surgery might be needed to correct the condition. Even more rarely, the eye might be so damaged that it has to be removed. The good news here, though, is that dogs that have reduced vision, or even no vision, adapt very well using their other senses, and can live a full, happy life with little or no eyesight.

Related Content:

Conjunctivitis (Pink Eye) in Dogs: Symptoms, Treatment & Is it Contagious?
A Look at the Canine Eye
Iris Cyst in Dogs

Checking Your Dog’s Eyes

I don’t know about you, but I’m a little bit squeamish about checking my dogs’ eyes. I do it, though, because I want my veterinarian to have all the information he needs in order to treat my dogs effectively. So, when you’re wondering if your dog has red eyes, beyond the usual irritation that he might experience due to allergens, you need to look at exactly where the “red” is. Is it on the outside of the eye? Between the colored part (the iris) and the sclera (the white part), or in the conjunctiva (the material that surrounds the eyeball and lines the lids)? The answers to these questions will largely determine how your dog’s condition is treated.

To check out your dog’s eyes, put him in a well-lighted area. Then, get a flashlight. Your dog probably won’t much like having the light shone in his eyes, so hold his head in our hands and speak softly to him before you shine the light. Then, under full light, take a look at his eyelids and his eyes. Take hold of each upper lid, and then pull down a bit toward the lower lid. Look at the underlying tissues, using the flashlight. How do your dog’s pupils respond? Ideally, they should narrow under full light, and expand under less light.

Next, put your thumb on the upper lids of your dog’s eyes, and press down gently. What you’re trying to do here is find out if they eyes feel hard when you do this. If your dog’s eyes are healthy, they should move.

Finally, check your dog’s “menace reflex.” What this is, is the way that your dog will react to a threat that he perceives visually. Place the palm of our hand about a foot and a half away from your dog’s eyes, and then gradually move it in to within three inches. If your dog’s eyesight is good, he’ll blink at some point. If he doesn’t, he might be blind. If you’re in doubt, do this several times, as a blind dog might simply react to the breeze that’s created when you move your hand.

Now What?

Having done these tests, you might still not know what it means if your dog has red eyes. So, take a look at his face. Is there any swelling, or any discoloration? If there is, that could mean that your dog has at some point sustained some sort of trouble that could explain red eyes and/or loss of vision. Warm, tender tissues can be an indication of eye trauma. If you see blood or pus, then you need to take your dog to the vet.

Also, check your dog’ pupils. Do they appear to be equal in size and do they dilate when you shine light? If they’re not, and they don’t, then that’s another reason for a visit to the vet. If the dog’s eyes are responding normally, though, you probably don’t have much to worry about.

Look, too, to make sure that the redness isn’t accompanied by a growth. Anything that looks abnormal should always be checked out. Bulging eyes accompanied by redness are also an indication that your dog could have a serious condition, so please don’t wait – take your dog to the vet.

The Final Word

When your dog has red eyes, it might mean something serious, or it could just be “one of those things” that doesn’t really require immediate attention. I always advise, though, if you’re in any doubt, to take your dog to the vet to be checked over. Unless you’re a real expert when it comes to dog health, you probably don’t know if what you’re looking at is nothing to worry about, or something that could be serious. It’s best not to take the chance.