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Why Are My Dog’s Eyes Red? 11 Common Causes

Dogs have eyes like their human counterparts. They can get dry, itchy, infected, injured, and teary for all kinds of reasons.

Of course, anything that relates to your dog’s eyes should be investigated. Mild eye irritations can be diagnosed and treated by your veterinarian. The key is to find out what’s wrong and give your dog the right treatment to keep his or her eyesight.

This post will cover some of the most common causes of red eyes in dogs, including diagnosis, treatment, and at-home care.

1. Corneal Ulcers

An abrasion or wound on the corneal surface is known as a corneal ulcer (or ulcerative keratitis).

Causes of corneal ulcers in dogs include trauma, damage from a foreign body, or chemical burns caused by household items like shampoo, medication, or cleaning products. Any kind of blunt trauma or laceration can cause a corneal ulcer.

In some cases, congenital issues are the source of the problem. For example, some dogs are born with distichia, a condition where an extra eyelash juts out from the margin of the eyelid and other locations.

As a result, the eyelashes end up scratching the surface of the cornea. Over time, the irritation leads to damage.

Corneal ulcers can also occur as a result of:

  • Keratoconjunctivitis sicca (chronic dry eye)
  • Neurological issues where the eyes are unable to blink properly
  • Diabetes mellitus
  • Autoimmune diseases (including Cushing’s disease and hypothyroidism)
  • Environmental irritants

Signs of Corneal Ulcers in Dogs

Signs of corneal ulcers in dogs include:

  • Frequent blinking
  • Swelling of the eyelid
  • Pawing at the eye
  • Rubbing their faces on the ground
  • Pus or bloody discharge in severe cases
  • Eye may appear red or blood-shot

Your dog may also show typical signs of pain including hiding behavior.

Treatment of Corneal Ulcers in Dogs

The type of treatment chosen will depend on the severity. Superficial ulcers that haven’t penetrated the deep layers of the eye might be treated with topical antibiotics and topical pain medications.

Deep corneal ulcers require surgical intervention.

Red Eyes in Dogs Image

2. Eye Infections in Dogs

Eye infections are pretty obvious in dogs. You may notice your dog has red eyes, is squinting more often, is pawing at the eye(s) and may have green or yellow discharge coming from the eye.

In many cases, eye infections are mild and are easily treated with a topical antibiotic. Other times, what appears to be an eye infection could be a sign of an underlying condition. This is why it’s important to have your dog seen by a veterinarian.

The sooner you can get that infection cleared up the better. If the veterinarian suspects something else is going on, he/she may suggest follow-up diagnostics.

The most common reasons for eye infections in dogs include the following:

Pink Eye (Inflammation of the conjunctiva)

Pink eye, also known as conjunctivitis, is an infection of the mucous membrane that covers your dog’s eye and eyelids. The conjunctiva serves as the eye’s defense against infections and foreign objects.

Dogs have something called a “third eyelid” that’s located at the inner corner of each eye. Most people don’t even notice this membrane unless it gets red or swollen.

There are a number of reasons why dogs develop pink eye including:

  • Common cold virus
  • Bacteria
  • Allergies
  • Irritation
  • Injury

Signs of Pink Eye in Dogs

Signs of pink eye in dogs can include one or all of the following:

  • Your dog’s eye may appear red
  • Scratching at the eye
  • Rubbing face on the carpet
  • Frequent squinting
  • You may see some discharge, especially if the pink eye was caused by bacteria

Treatment of Pink Eye in Dogs

It’s important to get a veterinarian’s diagnosis before attempting any at-home remedies for pink eye. If it’s caused by a virus, time and some steroid drops should help. If it’s bacterial, your vet may prescribe antibiotic drops or ointment.

3. Ulcerative Keratitis

Keratitis is an inflammation of the cornea. It mostly affects the surface layer (the corneal epithelium) that eventually causes the tissue to erode. If it gets into the deeper tissue (the corneal stroma) it is considered a corneal ulcer.

Signs of Ulcerative Keratitis in Dogs

Symptoms associated with ulcerative keratitis will depend on how long the dog has had the condition. Look for the following signs:

  • Increased tear production
  • Squinting
  • Eye rubbing
  • Eye discharge
  • Red eyes
  • You may notice a divot on the eye that is swollen and red

Causes of ulcerative keratitis include trauma to the eye, inability to completely close the eyelids, exposure to environmental irritants. There are 3 types of keratitis in dogs including non-ulcerative, ulcerative, and chronic superficial keratitis (pannus).

Treatment of Ulcerative Keratitis in Dogs

Treatment will depend on the cause of keratitis and may include antifungal medication or antibiotic drops.

Dogs with chronic superficial keratitis may be prescribed topical steroids in combination with immune-modulating therapy. The veterinarian may suggest decreasing your dog’s exposure to UV light as well.

Dogs with non-ulcerative keratitis can be treated on an outpatient basis. Severe cases may require radiation therapy or surgical removal of some of the cornea.

Reds eyes in dogs image

4. Allergies

Dogs who seem to always have red eyes may be suffering from allergic conjunctivitis. Typically, redness usually signifies the presence of inflammation and irritation. There are many types of environmental allergies that can cause your dog’s eyes to become red, itchy, and inflamed.

Seasonal allergies, for example, could include allergies to grass, mold, weeds, and pollen.

If you suffer from hay fever, you’ll have a pretty good idea of what it feels like. Your eyes get red, teary, swollen, and itchy. It’s a miserable condition that affects people and pets alike.

Treatment of Allergic Conjunctivitis

It’s often hard to narrow down the exact cause of an allergy, especially if your dog is allergic to multiple things. In order to provide a proper diagnosis, the veterinarian may recommend the following tests:

  • Conjunctival smear
  • Skin scraping around the eye to rule out parasites
  • Conjunctival culture
  • Schirmer tear test to detect dry eye

5. Congenital Abnormalities

Congenital abnormalities that affect your dog’s eyes are usually evident shortly after birth. There are many different types of congenital eye defects, including:

Canine Day Blindness (Achromatopsia)

This condition affects a dog’s ability to see clearly in bright light. Images appear blurry to affected dogs, but improves when the light get darker. It’s known to affect German Shepherds and Labrador retrievers.

Canine Multifocal Retinopathy

This condition affects a variety of dogs and is characterized by lesions on the retina.

This non-progressive retinal condition occasionally causes vision loss, especially when large lesions are present. As the dog matures, lesions appears less and eventually stop forming.

CMR is largely non-progressive; by the time a dog reaches adulthood, new lesions usually cease to form, and some lesions may even regress over time.

Congenital Stationary Night Blindness (CSNB)

This condition develops slowly and may result in total blindness. Changes to the eye are not usually visible until the affected dog is two or three years of age. By then, the disease has advanced and night blindness has developed.

Collie Eye Anomaly

The most common sign of this condition is blindness. The degree of vision loss depends on the severity of the condition. Carriers of this inherited condition include Rough and Smooth Collies.

Dry Eye Curly Coat Syndrome (CSS)

Cavalier King Charles Spaniels are prone to this condition where the eye is unable to produce tears.

The medical term for this condition is known as congenital keratoconjunctivitis sicca or ichtyosiform dermatosis.

The inability to produce adequate tears leaves the dog’s eyes vulnerable to injury and infection. Normally, a healthy eye can assist in removing foreign objects from the eye. Without the presence of tears, everyday irritants (hairs, dust, etc.) can cause permanent eye damage.

Infections and ulceration are painful and can lead to blindness.

Sadly, this disease is so painful and debilitating that affected dogs are usually euthanized. Unfortunately, there is no cure or preventative treatment.

Primary Lens Luxation (PLL)

PLL is characterized by weakened zonular fibers, the ligaments in the eye that hold the lens in place. In the case of a partial breakdown of zonular ligaments, the lens becomes partially dislocated. This is known as lens subluxation.

A complete ligament breakdown leaves the lens fully dislocated from its normal position. Lens dislocation can occur as a result of injury. PLL, however, arises spontaneously and is inherited in an autosomal recessive pattern.

Terriers and terrier mixed breeds are more prone to the condition.

Oculoskeletal Dysplasia (OSD)

Dogs with this condition tend to have shorter limbs along with severe ocular defects. These defects include:

  • Vitreous dysplasia
  • Retinal detachment
  • Cataracts

Progressive Retinal Atrophy (PRA)

Progressive retinal atrophy describes a group of inherited eye disorders that affect the retina.

Over 100 breeds have been diagnosed with various forms of PRA. The age of onset and the severity of the disease can vary widely. Sadly, this progressive disease leads to blindness in the final stages.

Primary Open Angle Glaucoma (POAG)

Generally speaking, glaucoma is an eye disease the causes intraocular pressure within the eye. Primary glaucoma results in increased intraocular pressure in an otherwise healthy eye and is inherited.

Unfortunately, the build-up of pressure causes irreversible damage to the optic nerves leading to luxation of the lens and narrowing of the iridocorneal angle. Eventually, this condition will lead to blindness.

Signs of POAG include red and dilated pupils.

6. Cataracts

Cataracts occur in people and pets. It occurs when the lens of the eye becomes cloudy. This process, known as opacification of the eye, leaves the victim with dimmed vision.

Signs of cataracts in dogs include:

  • Appearance of a cloudy-looking substance in the eye
  • Bumping into furniture
  • Trouble finding food sources, water, bed, etc.
  • Hesitant to walk down the stairs
  • May walk with their nose to the ground
  • Barking at objects (they can’t see what it is)
  • Weeping eyes
  • Nighttime anxiety
  • Flinching or easily startled

Treatment of cataracts in dogs

Surgical is the most common treatment for dogs with cataracts.

7. Primary and Secondary Glaucoma

Dogs can succumb to primary (inherited) or secondary (non-inherited) glaucoma. Primary glaucoma occurs on its own without any underlying disease causing it. Secondary glaucoma can occur as a result of secondary eye infections.

Unfortunately, glaucoma is a painful condition that can lead to blindness due to the build-up of pressure inside the eye. The increased pressure leads to permanent damage of the optic nerve.

The disease occurs when the eye is unable to drain through the filtration angles of the eye. The result is high pressure within the eye.

Signs of glaucoma in dogs

  • Eyeball may recede back into the head
  • Redness of the blood vessels
  • Cloudy appearance in the front of the eye
  • Dilated pupils
  • Enlarged eyeball
  • Dog may paw at the eye
  • Dog may show signs of pain (keeping eye partially closed, avoiding human touch near the eye, etc.)

Secondary glaucoma is a medical emergency.

Treatment for Glaucoma in Dogs

Treatment options depend on the type and stage of glaucoma. Your veterinarian may recommend medications to reduce pressure in the eye. A quick reduction in pressure may help avoid permanent blindness.

Painkillers and medications that encourage drainage while lessening fluid production are also prescribed.

Surgery is usually recommended for advanced cases of glaucoma in dogs. In fact, your veterinarian may recommend the complete removal of the eye to improve your dog’s quality of life. It’s an emotional decision, but at the end of the day you’d be surprised how quickly your dog adjusts.

8. Dry Eye

Dry eye syndrome (also known as Keratoconjunctivitis Sicca) occurs when there is decreased or inadequate tear production.

Normally, tear glands produce enough tears to keep the eyes lubricated and healthy.

Tears are more than just water. They actually contain antibacterial proteins, white blood cells, and other enzymes that keep eyes free from infection and irritants.

Dogs with dry eyes tend to be more susceptible to infection because there are not enough tears to wash away impurities.

Symptoms of Dry Eye in Dogs

  • Red and inflamed eyes
  • Redness and swelling of the tissues around the eye (conjunctiva)
  • Frequent blinking
  • Squinting
  • Discharge on the cornea (yellow or green if there is a secondary bacterial infection)

Treatment Options for Dry Eye

Veterinarians may prescribe cyclosporine or tacrolimus to stimulate tear production. Cyclosporine is usually the first choice because it can keep the immune system from harming the lacrimal and third eyelid glands. If that fails, tacrolimus is tried.

Dogs red eyes image

9. Uveitis

Uveitis involves the inflammation of the middle three layers of the eye and is associated with many different diseases.

Causes of the disease are divided into primary and secondary causes. For example, primary causes could include eye injury, infection, auto-immune disease, cataracts, and tumors of the eye.

Secondary causes of uveitis can include things like system infections or toxins that affect the whole body. Hormone diseases like diabetes can cause secondary uveitis as can cancer and high blood pressure.

Unlike glaucoma (which produces increased pressure within the eye), uveitis can cause low intraocular pressure within the eyes. It’s important to note that any change in pressure in your dog’s eyes will cause pain.

Signs of Uveitis in Dogs

Unfortunately, it’s not always easy to detect eye disease in dogs. Sometimes the signs are very subtle. Pet parents typically detect a problem when the eye is visibly red and inflamed. Depending on the underlying cause, signs of uveitis can include:

  • Signs of pain (squinting or closing the eye)
  • Rubbing the eye
  • Pressing their heads against furniture or objects

Treating Uveitis in Dogs

Treatment options depend on the source of inflammation along with the presence of any underlying conditions.

Anti-inflammatory eye drops are often used with pain relief to keep the dog comfortable. If the veterinarian suspects a bacterial infection is present, they may prescribe antibiotics.

If the cause of uveitis is due to trauma or injury, a specialist may be required to repair corneal tears or remove foreign bodies.

10. Prolapsed Third Eyelid Gland

This condition, also known as cherry eye, is caused by a herniated gland. Unlike some eye conditions, cherry eye is usually easy to spot because it causes a bulge in the corner of the eye.

Normally, a dog’s tear glands remain hidden under the eyelid. However, if the ligaments that keep the gland in place start to break down, it causes the gland to pop out.

The cause of cherry eye isn’t fully understood, but it does seem that brachycephalic breeds are often affected.

Dogs that may be more genetically susceptible to cherry eye include:

  • American cocker spaniels
  • Shih Tzus
  • Beagles
  • Lhasa apso
  • Pekingese
  • Maltese
  • Basset hounds
  • Rottweilers
  • Neapolitan mastiffs
  • Shar-peis
  • Boston terriers
  • Saint Bernard
  • English bulldogs

Signs of Prolapsed Third Eyelid Gland in Dogs

  • Appearance of a bulge in the corner of the eye
  • Pawing at the area
  • Inability to close the eye due to the growth
  • Dry eye can occur when tear production is inhibited

Treating Prolapsed Third Eyelid Gland in Dogs

Surgery is the only treatment option to cure cherry eye in dogs.

11. Foreign Object Embedded in the Eye

How many times have you seen a dog with his head hanging out of the window of a moving car? Dogs love the swish of fresh air and all the sights, sounds, and smells that come through an open car window. Unfortunately, it can lead to eye injuries.

If you’ve ever had a speck of dirt or sand (or even an eyelash) stuck in your eye, you understand the discomfort it causes. Dogs are just as susceptible to these things and it can lead to red, bloodshot eyes.

If your dog has healthy eyes, natural tear production will help clear foreign objects out of the eye. On the other hand, dogs with dry eye or other conditions may not be able to dislodge irritants. The longer there’s an irritant in the eye, the more discomfort your dog will have.

Over time, abrasive material in the eye can lead to scratches on the cornea, inflammation, and the risk of infection.

Diagnosing Eye Disease in Dogs

Diagnosis of eye disease is typically based on medical history and clinical signs. Diagnostic tests may include:

  • Corneal staining with fluorescein
  • Intraocular pressure testing
  • Corneal or conjunctival scrapings
  • Schirmer test to determine whether tear gland production is healthy

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Summing it up

Your dog may have red eyes for any number of reasons including the presence of a foreign object, viral infections, an allergic reaction to something, a fungal infection, or even disease.

Occasional bloodshot eyes may not be cause for alarm, but it’s always a good idea to get an accurate diagnosis from a licensed veterinarian. After all, we’re talking about your dog’s vision!

Many conditions can be treated successfully, or at least slow progression in some cases, if caught early.

Occasional redness in a dog’s eye may be simple irritants from the environment. Over-the-counter eye drops like Systane can help keep your dog’s healthy eyes lubricated and free from debris.

If your dog experiences persistent red eye along with any other symptoms of pain or itch, it’s probably time to seek the advice of a veterinarian. Any signs of pain or injury should be treated as soon as possible.

Remember, some eye conditions can cause permanent vision loss or even blindness if not treated early.

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