What Makes The Whites Of Your Dog's Eyes Red?

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If the whites of your dog's eyes turn red, they may be suffering from inflammation of the eyes or the tissues surrounding the eyes and should be seen by a veterinarian as soon as possible. The causes of red eyes or bloodshot eyes can be the result of trauma, irritation, infection, allergies, a foreign body in the eye, or eye diseases, requiring your veterinarian to diagnose the cause. If there's no foreign particle in the eye or an obvious scratch or ulceration, they'll conduct various tests based on a physical examination and related symptoms.


Does your dog have canine glaucoma?

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A red, painful eye is a primary sign that could indicate that your dog has canine glaucoma, a serious eye disease. Caused by a sharp increase in internal eye pressure, glaucoma often results in blindness. Redness is often the earliest sign of the disease, so it's crucial to your dog's future vision to have a red eye examined promptly. Other symptoms include a cloudy eye, excess tear production, eye enlargement, and a dilated pupil that's unresponsive to light.


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Your veterinarian diagnoses glaucoma by measuring the dog's intraocular pressure using a Tono-Pen or other tests. If caught early, topical medication and possibly laser surgery can reduce the intraocular pressure and preserve vision. In advanced cases, surgery may be necessary not to save sight, which is likely already gone, but to treat the intense pain connected with the condition. Only a veterinarian can determine definitively whether or not your dog has canine glaucoma.


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Why are my dog’s eyes red? It could it be canine uveitis

The uvea, containing blood vessels, is made up of three parts: the iris, the choroid, and the ciliary body. When there's inflammation inside the eye, the painful uveitis results. Besides the reddening, it's obvious by their behavior that your dog's eye hurts. Your dog will likely keep their eye closed and will avoid light. Other signs that your dog's red eyes could be canine uveitis include excessive tearing, cloudiness, and bloody eye discharge. If your dog is exhibiting any of these signs, they could have canine uveitis.


Some of these symptoms are quite similar to those of glaucoma, but uveitis is actually a different condition. In this disease, intraocular pressure is insufficient. Trauma, tumors, parasites, and various bacterial infections and viruses can cause uveitis.

Your veterinarian will perform a variety of diagnostic tests that may include bloodwork and ultrasound of the eye, and they'll test for diseases that cause uveitis. Your veterinarian will begin treatment aimed at reducing the inflammation and may refer you to a veterinary ophthalmologist depending on the cause and severity. Uveitis can turn into a chronic issue, and scarring can result in vision loss.



What is keratoconjunctivitis sicca in dogs?

Keratoconjunctivitis sicca, often referred to as KCS, "dry eye," or "dry eye syndrome," results when there is not enough lubrication from the tear ducts to keep the cornea, surface of the eye, and surrounding tissues moist. The tear glands aren't producing sufficient moisture, so the eye turns red and painful. Other symptoms include a copious, thick discharge from the eye.


Trauma, allergies, and various diseases can cause keratoconjunctivitis sicca. Your veterinarian likely will perform a Schirmer tear test to measure tear production and stain the eye for ulcer detection. Most dogs with dry eye require daily, lifelong administration of artificial tears to keep the eye adequately moistened. You'll have to clean your dog's eyes every day.


Can allergies cause red eyes in dogs?

Yes, allergies could be the culprit causing your dog's red eye problems.​ While humans and dogs don't always experience illness similarly, allergies in dogs can often present themselves just like allergies in humans. Dogs can be allergic to a multitude of things, including environmental allergens and seasonal factors, like pollen or fungus, as well as certain foods or soaps and other irritants.


If your dog has watery eyes or they are red or weepy and you notice them sneezing, itching, or pawing at their face or eyes, it could be an allergy. You'll want to bring them to your veterinarian to determine a course for diagnosis and treatment. Allergen panels should only be used for allergy serum injections, not to diagnose allergies.

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What is conjunctivitis in dogs?

Conjunctivitis is caused by bacteria, viruses, or irritants in the environment that infect or irritate the conjunctiva​, a thin tissue layer that covers the front of the eyeball and the inside of the eyelid. Conjunctivitis impacts the tissues that surround the eye, and this results in inflammation, itchiness, and a pink or red appearance to the sclera or whites of the eyes.


If you suspect your dog has pink eye, it's important to bring them to their veterinarian for an examination and treatment with medicated eye drops.

What is Horner’s syndrome in dogs?

If the third eyelid prominently appears in your dog's eye and is swollen and red, your pet might have Horner's syndrome.​ Other symptoms include sinking of the eye, a constricted pupil, and eyelid drooping. Although certain ailments can cause Horner's syndrome — including ear infections, tetanus, or muscle atrophy — most cases have no known cause. Fortunately, if the syndrome isn't related to an illness, Horner's syndrome should resolve by itself within several days.

Other causes of red in a dog’s eye

Some dog breeds that have eyes that bulge out are more prone to getting scratches in their eyes. Dog breeds like pugs or bulldogs have flatter faces and larger eyes. They are also smaller in stature so may be more likely to get their eye scratched by a stray twig or getting a in their eye foreign object while out walking.

Another possibility is cherry eye.​ This means the third eyelid has prolapsed from its normal anatomical position and is bulging outward. This condition can affect any breed of dog but it is more common in young dogs along with beagles, bloodhounds, Boston terriers, English bulldogs, bull terriers, cocker spaniels, Lhasa apsos, poodles, Saint Bernards, Shar Peis, and Shih Tzus.

How your veterinarian may diagnose your dog's red eyes

The first thing your veterinarian may do if your dog comes in presenting with red eyes is a physical exam and an ocular examination. They may also include some blood tests and take a urine sample to run some tests. At this point, it is very important to go through your dog's history and symptoms since even the smallest detail might help your veterinarian figure out the cause.


Since red eyes in dogs can be a result of something quite serious, diagnostic tests, like bloodwork and the ocular examination, are really important to rule out a serious illness. In order to rule out serious illnesses, your veterinarian may use an X-ray or ultrasound. They may test the eye's pressure; search for any physical damage, such as a tear in the cornea; and even take a biopsy or sample of some of the skin around or in the eye or eyelid.

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Treatment for a dog's red eyes and what you can do

Depending on what eye issues your veterinarian concludes is the cause of the red eyes, most of the time, it will include some kind of collar to help prevent your dog from exacerbating the issue. Again, treatment is contingent on the cause. If there is an issue with the cornea, such as ulcers or glaucoma, surgery may be necessary. Make sure that when your dog comes home, they stay clean and safe and don't injure or re-injure their eyes.

The bottom line

While eye redness in dogs could be benign, there are many medical causes that can become quite serious if left unchecked. These include eye infections, irritations, traumas, glaucoma, allergies, Horner's syndrome, conjunctivitis, and canine uveitis. The best way to be certain about the cause is to bring your dog to your DVM so that they can be assessed and tested as needed.


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