What causes red eyes in dogs

A dog’s eyes function a lot like our own. When normal and healthy, a dog’s eyes will take in light and transform it into images, like a food bowl or favorite toy. If those eyes become red and irritated, though, they can cause major discomfort and possibly not function very well. If your dog’s eyes are red, it will be important for you to know what’s causing the redness and what you can do to treat your dog’s eyes.

Causes of Red Eyes in Dogs

Dogs’ eyes can become red for a number of reasons. Common causes include:

1. Dry Eye (Keratoconjunctivitis sicca): Dry eye occurs when the eyes don’t produce enough tear film. Without tears to keep the cornea moist and free from debris or infectious agents, the cornea becomes dry and inflamed. This inflammation is quite painful and makes the eyes look red. Dry eye has many causes, the most common of which is immune-mediated adenitis, which damages tissue responsible for forming the watery portion of tear film.

2. Pink eye (Conjunctivitis): Pink eye occurs when the conjunctiva—the moist, pink tissue that lines the inner eyelids and front of the eyes—becomes inflamed. This inflammation causes redness. Environmental irritants like dust and pollen can cause pink eye.

3. Cherry eye: Dogs have a third eyelid that normally stays hidden. Some dogs have a genetic disorder that weakens the ligaments holding this eyelid in place, causing the eyelid to pop up and look like a cherry in the inner corner of the eye.

4. Corneal damage: Anything that can damage a dog’s cornea can cause eye redness. For example, if your dog is running through tall grass, a grass stalk can poke your dog’s eye and cause damage and irritation.

Other Eye Symptoms

Along with redness, you might notice some other eye symptoms:

• Squinting

• Mucus discharge

• Excessive blinking

• Swollen conjunctiva

• Constant eye rubbing

• Increased eye-watering

• Corneal scratches or scars

• A foreign object stuck in the eye

• Green or yellow discharge, indicating infection

What to Do About Eye Problems in Dogs

Eye problems in dogs are not always an emergency but do require prompt attention. If your dog’s eyes are red, call your veterinarian and try to schedule an appointment for that same day. When you schedule the appointment, provide a brief history of the redness, including when the redness started and what other symptoms you see.

Do not try to diagnose and treat the eye redness yourself. Your veterinarian has the expertise and equipment needed to properly examine your dog’s eyes and determine what’s causing the redness.

Also, do not delay taking your dog to the veterinarian. Eye problems can progress to something more serious—and possibly painful—if not treated promptly. The sooner your dog can be seen by your veterinarian, the better.

Diagnosis and Treatment

Your veterinarian will conduct a detailed eye exam, during which she will identify which parts of your dog’s eyes are red. If your vet suspects corneal damage, she will add a few drops of a fluorescent green dye on the cornea to see if there are any corneal scars or scratches.

If dry eye is a possibility, your vet will perform what’s called a Schirmer tear test to estimate the level of tear production. She may also take a small sample of watery fluid from your dog’s eyes to determine if there is an underlying bacterial infection.

Your veterinarian will recommend treatments according to what’s causing the eye redness. For example, if your dog has dry eye, your veterinarian will prescribe medications like cyclosporine, which stimulates tear production, or artificial tears. If your dog has cherry eye, your veterinarian will surgically anchor the third eyelid into place. Other treatments include anti-inflammatory medications and dog antibiotics.  

Eye medications are typically formulated as ointments or eye drops. Before you leave your appointment, make sure you understand how to properly administer the medications that your dog will need. If you have not given your dog topical eye medications before, ask your vet to demonstrate how to do so.

Keep in mind that not all dogs like receiving eye drops or eye ointments. You may need to be patient with your dog and allow extra time to give the medications.

Living and Management

How you manage your dog’s eyes after initial treatment will depend on what caused the redness. With dry eye, for example, you will need to regularly administer the topical eye medications, clean your dog’s eyes with a prescribed eyewash, and take your dog to follow-up appointments every six to 12 months.

If dust and pollen are irritating your dog’s eyes, then your vet may recommend that you frequently dust your home or limit your dog’s time outside when the pollen count is high. Cherry eye can recur after surgical treatment, so you will need to monitor if your dog’s third eyelid pops up again.

Your veterinarian will help you determine which management strategy will work best to prevent future eye redness.

As pet owners, we all become concerned if we notice something wrong with our beloved canine. If you have noticed a red eye or eyes on your dog, several factors could be causing it. We will review the 13 most common causes of red eyes in dogs and give you some valuable advice on how to handle it.

Why Are My Dog’s Eyes Red? (13 Reasons)

We can all relate to this; a small object can enter our eyes and cause irritation. Dust, grass, hair, or a small flying insect stuck to the eye surface or under the eyelids can cause a red eye. A foreign body on the eye usually affects only one eye, with some exceptions. For example, if your dog was running around in a very dusty place, it might have gotten dust in both eyes. Try to visually inspect the eye, and if you see anything on the eye, you could try flushing the eye with a 0.9% saline solution. Chances are your dog might resist the treatment, or you might not feel comfortable doing it. In this case, make a quick visit to the vet. Once the foreign object is washed out, your dog’s eye will return to normal in a few hours.

Allergies are a common cause of red eye in dogs. Pollen, dust, weeds, mold, mites, and even food are common allergens that can cause red, itchy, and watery eyes. Sometimes, allergies are presented with other symptoms, such as runny nose, sneezing, and itchy skin. As part of the treatment, it is important to determine what the dog is allergic to. This can be done with a series of tests or with elimination diets. Your veterinarian will help you discover the cause of the problem. The treatment might include antihistaminic or anti-inflammatory drugs.

Conjunctivitis is an inflammation of the conjunctiva, the clear layer of soft tissue covering the eye. This can be either infectious, caused by viruses or bacteria, or non-infectious, caused by allergens or irritant substances. Most cases of conjunctivitis are accompanied by puffy eyes or swollen eyelids, and they also present with some kind of abnormal eye discharge. The treatment will depend on the underlying factor causing it, so visit your vet to get an appropriate diagnosis of the cause.

Like humans, dogs can suffer from dry eyes due to a lack of enough tear production. The veterinarian will perform a Schirmer tear test to evaluate the secretion level of the tear glands. It consists of placing a special paper stripe on your dog’s eye and measuring the number of tears produced in one minute. If the tear production is insufficient and the diagnosis is dry eye, you will need to apply lubricating eye drops on your dog’s eyes a couple of times a day. Some cases will be resolved after a few days, but other cases are chronic. That means the dog will require eyedrops a couple of times a day for the rest of its life.

Another common cause of red-eye in the dog is entropion. This abnormality causes the eyelid to roll inward, so the eyelashes are rubbing against the eye, causing irritation, discomfort, and, in the worst case, ulceration of the cornea. The medical treatment for this condition is surgery.

In the case of Distichiasis, there is an extra set of eyelashes growing towards the inside of the eye. Like entropion, it causes irritation and can also lead to a corneal ulcer. The treatment is to remove or destroy the follicles of the abnormally growing eyelashes with electrolysis, cryotherapy, or surgery.

A corneal ulcer is the perforation of the thin, transparent layer on the eye’s surface. Corneal ulcers are very painful and can get infected. The possible causes are trauma, abrasions, substance irritations, dry eye, infections by bacteria, fungus or virus, and parasites. To diagnose a corneal ulcer, the vet will perform a fluorescein test applying a fluorescent green substance to the eye to see any potential perforation. The treatment will depend in part on the cause, but usually, the dog will need several eyedrops a few times a day, a cone collar to avoid further lacerations, and oral anti-inflammatory medication. Extreme cases could require surgery.

Blepharitis is an inflammation of one or the pair of eyelids, affecting one or both eyes. Causes of this can be infection, trauma, irritation, or allergies. It could also be caused by a tumor. The vet will need to find out the cause of blepharitis to be able to treat it accordingly.

When cherry eye occurs, the incitant membrane or third eyelid protrudes due to a teat gland that becomes inflamed and forces it out of place. A pink or red bump is visible, poking out from the lower eyelid. This ophthalmological condition needs surgery; the sooner, the better.

Uveitis is an inflammation of the uvea that consists of the iris, ciliary body, and choroid. Any or all three structures can become inflamed by infections of viruses, bacteria or fungi, and parasites. It can also be caused by toxins, irritations, trauma, high blood pressure, or metabolic disease such as diabetes. Treatment consists of decreasing the inflammation and treating the primary cause of this problem. If the vet diagnoses uveitis, your dog might be referred to a veterinary ophthalmologist because some cases are complicated and become recurrent.

Hyphema is blood trapped between the cornea and the iris. It is usually caused by trauma, but ulceration, hypertension, glaucoma, toxicosis, coagulation, or platelet disorders can also lead to this condition. Your vet will treat it depending on the causal factor.

Glaucoma is a very painful condition in which the internal pressure of the eyeball is increased due to fluid buildup. Glaucoma damages the optical nerve and can cause blindness. The vet uses a specialized medical tool called a tonometer to measure the pressure of the eye. Early detection makes treatment easier. Sometimes topical treatment with eye drops can be used, but other cases need laser surgery.

Tumors of the eyelids and glands can also cause red-eye in your dog. A variety of benign and malign tumors can affect the different structures of the eye. The treatment depends on the kind and placement of the growth and varies from surgical removal to radiation, completely removing the eye (enucleation) in the most severe cases.

• Related Read: Common Eye Problems for Dogs

Conclusion: Red Eyes in Dogs

Red-eyes in a dog can be caused by something as simple as a dust particle. But it can also be as serious as a tumor that requires the eye to be removed. If this happens suddenly and you can see a particle on the eye, rinsing out the eye with a saline solution should do the trick.

However, if the eye remains red after a couple of hours, it is necessary to visit the veterinarian to figure out what of the many possibilities is causing your dog’s eye to be red and find the appropriate treatment to resolve the issues before they complicate further.

• Related read: Cancer In Flat-Coated Retrievers: Is It Common?

Featured Image Credit: Tatiane Silva, Shutterstock