It is concerning to constantly wonder why your dog’s eyes are red. While it is common for dogs to have red eyes occasionally, persistent redness could indicate an underlying health condition. The causes of red eyes in dogs can range from minor irritations to serious eye diseases.

Even with proper eye care and hygiene, like using vet-approved eye wipes, your dogs can suffer from occasional redness. While some reasons for the redness are harmless, some may be severe, needing prompt medical attention to prevent eye damage.

We have expounded red eyes in dogs with the help of experts and sources like the Clinical Atlas of Canine and Feline Ophthalmic Disease and MSD manuals. Since the eyes are one of the most delicate organs, it’s best to err on the side of caution and visit your vet when you suspect an eye problem.

So, Why Are My Dog’s Eyes Red?

Red eyes in dogs can result from various reasons, including allergies, infections, foreign objects, injuries, and eye diseases like glaucoma, dye eye, uveitis, and conjunctivitis. Of these reasons, allergies are the most common cause of canine eye redness and, luckily, the easiest to treat. How long the redness persists may determine the cause and severity.

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It’s tough to watch your dog struggle with their eyes. In our article on how to treat bloodshot eyes we cover what to do if your dog’s eyes are red. In this article, we are going to go far more in depth about what causes red eyes in dogs. You must have also struggled with an eye issue at one point, so you know it’s not fun for your dog.

It is essential to take your canine to a veterinarian if you notice redness in their eyes, especially if it is accompanied by other symptoms such as discharge, swelling, or vision changes. The veterinarian can determine the underlying cause and recommend appropriate treatment.

Also see our article on why dog’s pupils dilate when they look at you.

Understanding Red Eyes in Dogs: Types of Red Eyes

Various factors can cause red eyes in dogs, and understanding the different types of red eyes can help dog owners identify the underlying cause and seek appropriate treatment. In the guide below, we give you visuals of every kind of red eye that could affect your dog.

But first, let’s discuss the different types of red eyes in dogs:

Episcleral Injection

Episcleral injection is when the blood vessels in the white part of the eye (sclera) become dilated and visible, giving the eye a red appearance. Episcleral injection is mostly an external sign of an intraocular disease like glaucoma. In the image above, a dog has glaucoma and clear secondary episcleral injection.

This can be caused by various factors, including allergies, infections, and eye injuries. Episcleral injection is not usually painful and does not affect vision, but it can be a sign of an underlying condition that requires treatment.

Subconjunctival Hemorrhage

Subconjunctival hemorrhage is a condition where the blood vessels in the conjunctiva (the clear membrane that covers the white part of the eye) rupture and bleed, causing a red patch on the eye. This is probably most common in dogs with short noses and prominent eyes, like pugs, but this can also happen in any breed.

Subconjunctival hemorrhage is usually painless and does not affect vision, but it can be a sign of an underlying condition that requires treatment. A study showed that 119 out of 147 cases of dogs with subconjunctival hemorrhage resulted from trauma and accidents.

Conjunctival Hyperemia

Conjunctival hyperemia is when the blood vessels in the conjunctiva become dilated and visible, making the eye look red. In the picture above, a dog has very bad hyperemia as a result of lymphoma.

However, it can be caused by various factors, including allergies, infections, and irritants. Conjunctival hyperemia is usually not painful and does not affect vision, but it can be a sign of an underlying condition that requires treatment.

Corneal Neovascularization

Corneal neovascularization is when new blood vessels grow into the cornea (the clear outer layer of the eye), causing a red appearance. This can be caused by various factors, including infections, trauma, and corneal ulcers.

Corneal neovascularization can affect vision and requires prompt treatment to prevent complications.

Hyphema

Hyphema is a condition with bleeding in the front chamber of the eye, causing the eye to appear red. This can be caused by various factors, including trauma, infections, and blood clotting disorders. Hyphema can be painful and can affect vision, requiring prompt treatment to prevent complications.

In the image above, the dog has hyphema from uveitis resulting from uveodermatologic syndrome that we will discuss below. It is also a kind of intraocular bleeding. This occurs when blood vessels in the eye rupture, causing blood to leak into the eye. Intraocular bleeding can be caused by various factors, including trauma, infections, and tumors.

13 Common Causes of Red Eyes in Dogs

A variety of factors can cause red eyes in dogs. Some of the most common causes of red eyes in dogs include:

1. Allergies

Allergies are a common cause of red eyes in dogs, or allergic conjunctivitis that is most common in West Highland Terriers and English Bulldogs. Dogs can be allergic to various things, including pollen, dust, and certain foods. The most common signs besides eye redness include sneezing, face swelling, rashes and hives, rubbing their eyes on the carpet, and even wheezing.

When a dog is exposed to an allergen, their immune system can react by producing histamines, which can cause redness and inflammation in the eyes.

2. Infections

Infections can also cause red eyes in dogs. Bacterial, viral, and fungal infections can all lead to eye redness and inflammation. Bacterial infections can result from Staphylococcus and Streptococcus and viral infections from the common canine distemper and also adenovirus.

Infections can be especially dangerous if left untreated, as they can lead to more serious health problems. Canine herpesvirus (CHV) ocular disease is a condition that can cause redness in the eyes of dogs. It occurs when the herpes virus infects the eyes, leading to inflammation and redness. The image above shows the eye of a dog with herpesvirus disease.

3. Injury

Injury is another common cause of red eyes in dogs. Dogs can injure their eyes in various ways, including scratches, cuts, and blunt force trauma. Injuries can cause redness, swelling, and pain in the eyes. The image above shows one of the most common types of eye injuries, which is a corneal ulcer.

4. Glaucoma

Glaucoma is a condition that can cause red eyes in dogs. Glaucoma occurs when there is an increase in pressure within the eye, which can lead to damage to the optic nerve.

Glaucoma can be a serious condition that can lead to vision loss if left untreated. A study showed that breed-related glaucoma was most prevalent in American Cocker Spaniels, Basset Hounds, Wire Fox Terriers, Boston Terriers, and Frenchies.

5. Cherry Eye

Cherry eye is a condition that can cause redness in a dog’s eyes. It occurs when the gland that produces tears in the eye becomes swollen and protrudes from the eye. Cherry eye can be treated with surgery.

Cherry eye is a major cause of a pink bump forming around a dog’s eye. While not usually painful, it can lead to secondary eye problems if left untreated.

6. Foreign Objects and Environmental Irritants

Foreign objects, such as dirt, dust, or debris, can also cause redness in the eyes of dogs. When a foreign object enters the eye, it can cause irritation and inflammation. One common symptom is squinting or keeping one eye shut.

Environmental irritants, such as dry air, smoke, and excess sun exposure, can also cause redness. These irritants can cause dryness and inflammation in the eyes.

7. Uveitis

Uveitis is a condition that can cause redness in the eyes of dogs. It occurs when the middle layer of the eye becomes inflamed.

Uveitis can be caused by various factors, including infections, trauma, and autoimmune disorders. This condition can cause severe pain to your dog, resulting in them squinting and avoiding light.

8. Conjunctivitis

Conjunctivitis is a condition that can cause redness in the eyes of dogs. It occurs when the conjunctiva, the thin membrane covering the eye’s white part, becomes inflamed.

Conjunctivitis can be caused by various factors, including infections, allergies, and irritants. You can read our article on can dogs get pink eye for more information on canine conjunctivitis.

9. Dry Eye

Dry eye or Keratoconjunctivitis sicca (KCS) is a condition that can cause redness in the dogs’ eyes. It occurs when the eye does not produce enough tears, leading to dryness and inflammation.

10. Eyelid and Eyelash Abnormalities

Many dogs can be born with genetic abnormalities in their eyelids or eyelashes. There are a few different kinds, but three of the most common that cause red and irritated eyes in dogs are entropion, ectropion and trichiasis. Entropion means the eyelid turns inwards, so they eyelashes are constantly irritating the eyelash and with ectropion, the eyelids turn outward. This is common in breeds with droopy skin and wrinkles.

The image below, a bulldog has both entropion and ectropion (called diamond eye).

Eyelash disorders that cause the eyelashes to grow an extra row or to turn inwards are another common issue. The dog below has an eyelash problem called trichiasis, where the upper lashes are turning inward and constantly irritating the eye.

Dogs can also get a bump on their eyelid called a chalazion that can irritate the eye and cause redness.

11. Straining, Coughing, or Throat Pressure

Straining, excessive coughing, or throat pressure can also cause redness in the eyes of dogs. These actions can cause increased pressure in the eyes’ blood vessels, leading to redness and inflammation.

12. Cancer

Cancer is a less common but severe cause of red eyes in dogs. Tumors in or around the eye can cause redness and inflammation. It can also lead to pressure on the eyeball leading to issues like hyphema.

13. Other Eye Diseases

Ocular disease is a general term that encompasses a variety of conditions that can cause redness in the eyes of dogs. These conditions can include cataracts, retinal disease, and corneal disease.

Other eye issues causing redness include:

Uveodermatologic Syndrome

Uveodermatologic syndrome is a rare condition that can cause redness in the eyes of dogs. It occurs when the immune system attacks the melanin-producing cells in the body, leading to inflammation in the eyes and skin.

Blood Clotting Disorders

Blood clotting disorders can also cause redness in the eyes of dogs. These disorders can cause eye bleeding, leading to redness and inflammation.

Blepharitis

Blepharitis is a condition that can cause redness in the eyes of dogs. It occurs when the eyelids become inflamed, leading to redness and swelling. Studies have shown that short-muzzled dogs (brachycephalic) are more susceptible to the condition.

Systemic Hypertension

Systemic hypertension, or high blood pressure, can also cause redness in the eyes of dogs. High blood pressure can

Symptoms Associated with Red Eyes

The following are some common symptoms associated with red eyes in dogs.

Discharge

One of the most common symptoms of red eyes in dogs is the presence of discharge. This can be a clear or cloudy fluid that may be watery or thick. Discharge can be a sign of an infection or injury and may also indicate an allergic reaction or other underlying condition. It’s essential to learn how to clean dog eye boogers if they have discharge.

Squinting

Dogs with red eyes may also squint or blink excessively. This can be a sign of discomfort or pain and may be due to the presence of foreign objects in the eye, an infection, or other issues. Squinting can also be a sign of allergies or other underlying conditions.

Swelling

Swelling around the eyes is another symptom that may accompany red eyes in dogs. This can be due to an allergic reaction, an infection, or an injury. Swelling can also signify a more serious condition, such as glaucoma or other eye diseases.

It’s important to note that these symptoms may not always be present in dogs with red eyes, and some dogs may exhibit other symptoms not listed here.

Diagnosing Red Eyes in Dogs

When a dog’s eyes appear red, it can indicate an underlying issue. Diagnosing the cause of red eyes in dogs is vital to ensure proper treatment. Here are some common causes of red eyes in dogs and how to diagnose them.

Conjunctivitis

Conjunctivitis, also known as pink eye, is a common cause of red eyes in dogs. Allergies, infections, or irritants can cause it. Here, a veterinarian will examine the eye and may take a sample of the discharge to determine the cause of the infection.

Corneal Ulcers

Corneal ulcers are another cause of red eyes in dogs. They occur when the cornea is damaged, allowing bacteria to enter the eye. Symptoms of corneal ulcers include redness, discharge, and squinting.

A veterinarian can diagnose a corneal ulcer by examining the eye and using a special dye to check for damage to the cornea.

Glaucoma

Glaucoma is a severe condition that can cause red eyes in dogs. It occurs when increased pressure in the eye can damage the optic nerve and lead to blindness. Symptoms of glaucoma include redness, pain, and a cloudy eye.

A veterinarian can diagnose glaucoma by measuring the pressure in the eye and examining the optic nerve.

Other Causes

Other conditions, such as uveitis, dry eye, or a foreign object in the eye can also cause red eyes in dogs. To diagnose these conditions, a veterinarian will perform a thorough eye exam and may conduct additional tests, such as blood work or X-rays.

Treatment Options

Medication

A veterinarian may prescribe antibiotics or antifungal medication to treat bacterial or fungal infections. Anti-inflammatory medication such as steroids may also be prescribed to reduce eye inflammation and redness.

Surgery

In some cases, surgery may be necessary to treat the underlying cause of red eyes in dogs. For example, if the redness is caused by a tumor or foreign object in the eye, surgery may be necessary to remove it. Surgery may also be necessary to correct structural abnormalities in the eye that are causing redness.

Home Care

In addition to medication and surgery, some home care options may help reduce redness in a dog’s eyes. These include:

Warm compresses: Applying a warm compress to the affected eye can help to reduce inflammation and promote healing.
Eye drops: Over-the-counter eye drops may soothe and moisten the eyes. However, it is essential to use eye drops specifically formulated for dogs and to follow the instructions carefully.
Environmental changes: If allergies or irritants cause redness in the dog’s eyes, changing the dog’s environment may be necessary. For example, switching to hypoallergenic bedding or using air purifiers may help to reduce irritation.

It is essential to consult a veterinarian to determine the best treatment for a dog with red eyes. Early treatment can help to prevent complications and ensure a speedy recovery.

Prevention Strategies

Regular Eye Exams

Schedule regular eye exams with a veterinarian to catch any eye issues early on.

Cleanliness

Clean your dog’s eyes with a damp cloth or eye wipes. This will help remove any dirt or debris that may irritate the eyes.

Avoid Irritants

Keep your dog away from irritants such as smoke, dust, and pollen. These can cause redness and irritation in the eyes.

Proper Nutrition

Feed your dog a balanced diet with essential vitamins and minerals. This will help keep your dog’s eyes healthy and prevent any eye issues.

Protection

Protect your dog’s eyes from the sun and wind by using dog goggles or a visor. This will help prevent any damage to the eyes.

Following these simple prevention strategies can help keep your dog’s eyes healthy and prevent any redness or irritation.

When to See a Vet

If a dog’s eyes are red and showing other symptoms such as discharge, swelling, or squinting, it is recommended to take them to the vet as soon as possible. These symptoms could indicate a serious eye infection or injury that requires medical attention.

Additionally, if a dog’s red eyes persist for over a day or two, it is best to seek veterinary care. The vet can examine the dog’s eyes to determine the cause of the redness and provide appropriate treatment.

If a dog has a history of eye problems or is prone to eye infections, it is essential to have regular check-ups with a veterinarian to catch any issues early on.

Frequently Asked Questions (FAQs)

Can red eyes in dogs be a sign of allergies?

Yes, red eyes in dogs can be a sign of allergies. Allergies can cause inflammation and irritation in the eyes, leading to redness. Common allergens include pollen, dust, and certain foods.

What are the common causes of red eyes in dogs?

Common causes of red eyes in dogs include allergies, infections, injuries, and underlying health conditions such as glaucoma or dry eye syndrome. Environmental factors such as exposure to smoke or chemicals can also cause redness.

How can I tell if my dog’s red eyes are a sign of something serious?

If your dog’s red eyes are accompanied by other symptoms such as discharge, swelling, or changes in behavior, it may be a sign of something serious. It is always best to consult with a veterinarian to determine the underlying cause and appropriate treatment.

What are some home remedies for treating my dog’s red eyes?

Some home remedies for treating red eyes in dogs include using a warm compress, cleaning the eyes with saline solution, and providing a healthy diet with omega-3 fatty acids. However, it is important to consult a veterinarian before trying home remedies.

Can stress cause red eyes in dogs?

Yes, stress can cause red eyes in dogs. Stress can lead to inflammation and irritation in the eyes, causing redness. It is essential to identify and address the source of stress to prevent further health issues.

When should I take my dog to the vet for red eyes?

If your dog’s red eyes persist for more than a day or are accompanied by other symptoms, it is best to take them to the vet for a thorough examination. Additionally, if your dog has a history of eye problems or underlying health conditions, it is essential to seek veterinary care.

Final Thoughts

Red eyes in dogs can be caused by various factors, including allergies, infections, irritations, and underlying health conditions. If a dog’s eyes are consistently red or accompanied by other symptoms such as discharge, swelling, or discomfort, it is important to seek veterinary care to determine the underlying cause and appropriate treatment.

Meet Your Experts

Tamsin De La Harpe

Author

Tamsin de la Harpe has nearly two decades of experience with dogs in rescue, training, and behavior modification with fearful and aggressive dogs. She has worked closely with veterinarians and various kennels, building up extensive medical knowledge and an understanding of canine health and physiology. She also spent two years in the animal sciences as a canine nutrition researcher, focusing on longevity and holistic healthcare for our four-legged companions. Tamsin currently keeps a busy homestead with an assortment of rescue dogs and three Bullmastiffs.