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Your pet’s eye or eyes appear red in color due to increased inflammation. This inflammation can be on the eyelids themselves leading to the red appearance or even due to the blood vessels becoming enlarged on the whites of the eyes known as the sclera. The blood vessels can enlarge or engorge with blood due to either something occurring on the outer portions of the eye or something internally in the eye.


There are many different causes of red eyes in dogs and can be as simple as allergies or more serious such as glaucoma or increase in pressure in the eye. Other potential causes could be an infection inside the eye, an ulcer on the outer portion of the eye that could be due to a trauma event, low tear production, or an infection either inside the eye or outside the eye. There are cases of disease elsewhere in the body that can lead to inflammation of the eye.


Several tests that can be completed by your veterinarian to try to diagnosis the issue with the eye. The first step involves looking at the eyes with a specialized ophthalmoscope in both the light as well as in the dark to look at the back of the eye at the nerves and vessels. The veterinarian will check the responses of the pupils as well as the response of the eyelids to the light. This will ensure that the nerves to the eye are working properly. The next step with this is to look at the inner portions of the eye for evidence of infection/cells in the eye chambers as well as to look at the lens.

More specialized testing can involve taking the tear production of the eyes to ensure there is enough lubrication of the eyes. Another common test is called Fluorscein dye test. It will turn the outer portion of the eye called the cornea a green color to look for any signs of trauma or an ulcer on the eye. Also, the veterinarian may take a pressure check of the eyes to ensure there are no signs of glaucoma. Sometimes pets have to be referred to a veterinary ophthalmologist if there are concerns about glaucoma or other issues in the eyes.


Treatment for redness of the eye can range from special eye drops and oral anti-histamines that help with the inflammation if it is allergy related to even antibiotic eye drops if there is a cut on the eye. To ensure there is not a serious issue involved, have your pet seen if their eyes are red.

Want to read more about pet allergies? Check out our post: Itchy and Scratchy: A Primer on Spring Pet Allergies!!

Causes of Eye Redness in Dogs

When dogs see the veterinarian for eye redness, here are the typical causes:

  • Trauma. Nothing causes eye redness in dogs more reliably than a poke to the eye with a branch or other foreign object.
  • Environmental irritants. Cigarette smoke, pollen, dust, and other irritants can cause eye redness in dogs.
  • Bacterial conjunctivitis. This often occurs secondarily to another eye condition, but it can cause eye redness in dogs.
  • Viral conjunctivitis. This form of conjunctivitis (inflammation of the lining of the eye) is more common than the bacterial form, especially in dogs with distemper.
  • Corneal disease. Diseases of the cornea – such as pannus – can affect not only the clear covering of the eye but other eye structures as well.
  • Glaucoma. Increased pressure in the eye can cause redness in the whites of the eye.
  • Skin disease. Mange, cancer, and skin allergies can all cause irritation, itching, and eye redness in dogs.
  • Systemic disease. Eye problems can often indicate other systemic and related disease, including pannus, leptospirosis and Rocky Mountain Spotted Fever.

What Your Veterinarian Will Do About Eye Redness In Dogs

When your dog visits the veterinarian for eye redness, there are a few diagnostics that need to be done to determine the cause of the problem. These may include:

  • A full physical exam
  • A medical history and your observations of your dog’s behavior
  • An ocular exam, including evaluation of the inside of the eye, nerves, and lens
  • A corneal stain
  • Intraocular pressure
  • Tests to determine eye dryness
  • Skin evaluation
  • Allergy testing

If your dog’s eye problem is severe, we may refer your dog to a veterinary ophthalmologist for further diagnostics and treatment.

Watchful and Aware

It’s important to note that eye problems, especially if painful for your dog, are considered emergencies and should be seen immediately. Watch for:

  • Pawing at the eye
  • Squinting, refusing to open the eye
  • Discharge from the eye
  • Swollen or red eye or eyes
  • Opaqueness of the eye

Many eye problems can be accompanied by other signs such as poor appetite, lethargy, or fever.

If you are on your way to the veterinarian, a cool compress with a damp cloth can be soothing. Try to avoid actually touching the surface of the eye. Prevent your dog from pawing at or itching the eye by placing a soft e-collar until you can get to the veterinarian. Never put anything into your pet’s eyes without consulting your veterinarian.

If you have any questions about eye redness in dogs or eye health, please don’t hesitate to give Leon Valley Veterinary Hospital a call.

PET Q and A: My dog appears to have bloodshot eyes. What could this mean? Bloodshot eyes can be the result of a variety of causes, some very minor and some much more serious that require immediate veterinary attention.

Q. My dog appears to have bloodshot eyes. What could this mean?

Bloodshot eyes can be the result of a variety of causes, some very minor and some much more serious that require immediate veterinary attention. The red discoloration of your dog's eye(s) is due to the infiltration of blood vessels to either a small, irritated part of the eye or a more generalized condition. It is important to continually monitor your pet for development of redness on the whites of his or her eyes and/or within the eyes themselves.

The most common causes of red eyes in dogs:

* Environmental irritants and allergens: Like people, elements in the environment such as dirt, dust, and cigarette smoke can irritate your dog's eyes. Your dog may also develop environmental allergies to trees, grasses, flowers, insects, etc. The irritation caused by these allergens or irritants causes the mucous membranes surrounding the eyes to become inflamed, red and sometimes watery just as in people. This is commonly seen during the spring and summer months, but it can happen year-round.

* Trauma: Objects such as sticks, dust particles or small objects are prone to becoming lodged in your dog's eye. The foreign material results in inflammation and the influx of blood vessels to that irritated area causing your dog's eye to appear red.

* Corneal ulcers: The cornea is the clear, outer layer of the eye that is important for allowing light into the eye. When the cornea is injured and a defect (erosion or ulcer) forms, the eye becomes very painful and can eventually become infected. In dogs, there are many causes for corneal ulcers such as trauma, eyelash or eyelid disorders, dry eye, and secondary bacterial infections. A corneal ulceration results in severe inflammation in the eye. The body responds by sending blood vessels from the outer margins around the eye to the ulcerated site to help heal the ulcer. Blood vessels are important for healing because they carry essential nutrients to the injured site. Blood vessels grow approximately 1-2 millimeters in length every few days. The sight of blood vessels extending towards an ulcer is a good sign that the ulcer is trying to heal. Signs indicating that your dog may have a corneal ulcer include squinting, keeping the eye closed, discharge from the eye, redness of the eye, lethargy, decreased appetite, or decreased playfulness. If you observe any of these signs, have your dog examined by a veterinarian as soon as possible. In severe cases where the ulcer becomes deep and left untreated, the eye may rupture and result in pain and loss of vision, thus immediate veterinary attention is recommended.

* Glaucoma: This disease is characterized by an increase in the pressure within the eye. Breeds that are commonly pre-disposed to developing glaucoma include cocker spaniels, basset hounds, and shar peis, particularly females. An increase in intra-ocular pressure can occur suddenly or over several weeks, months, or even years. Acute glaucoma is very painful and requires immediate veterinary attention. Signs to look for include pain from redness of the whites of the eyes, redness of the mucous membranes around the eye, squinting, lethargy and decreased appetite. A bluish discoloration of the cornea and decreased visibility may also be observed. Glaucoma usually presents itself only in one eye initially, but it may eventually also affect the other eye. If glaucoma develops chronically, the affected eye may become larger in size than the unaffected eye.

* Uveitis: Uveitis is inflammation of the middle-layers of the eye. Common causes of uveitis in dogs include trauma, a variety of inflammatory conditions, tick-borne diseases, immune-mediated diseases, cataracts, and cancers within the eye. The severe inflammation within the eye causes the influx of blood vessels onto the eye. Blood may also collect in the anterior chamber of the eye.

* Lens luxation: The lens is an elliptical structure within the eye behind the iris (colored portion of the eye) that helps to bring light rays into focus onto the retina in the back of the eye. Trauma, glaucoma, uveitis, or genetic predispositions (particularly in Jack Russell terriers) can cause the lens to become displaced from its original position into either the front or the back of the eye. When the lens is luxated, it can be observed moving around in the eye. If the lens is displaced to the front of the iris, this is a surgical emergency. It results in severe inflammation, pain and injection (redness) of the eye. If you observe this, have your dog seen by a veterinarian immediately.

* Dry eye syndrome (keratoconjunctivitis): Like people, dogs can get dry eye when the tear film, which serves to provide nutrients and moisture to the outer portion of the eye, is deficient in the water component. This deficiency causes the cornea to dry out, predisposing the eye to corneal ulcers. A dry eye is very painful and red. The majority of dry eye in dogs is inherited, particularly in bull-dogs, American cocker spaniels, schnauzers, and Lhasa apsos, but any dog can get dry eye.

* Conjunctivitis: Conjunctivitis is inflammation of the mucous membranes that line the inner eyelids and the outer margins of the whites of the eyes (the conjunctiva). This inflammation causes the conjunctiva to become swollen and red. Discharge from the eyes may also be seen. Conjunctivitis in dogs is commonly secondary to an underlying eye or systemic disease such as a bacterial, viral, parasitic or tick-borne infection. Other causes include allergies and follicular conjunctivitis seen in younger dogs.

If you observe that your dog has bloodshot eyes, have it seen by a veterinarian as soon as possible.

Red Eyes in Dogs: Cause for Panic or No Biggie?

If you notice your pet’s eyes looking red or irritated, you probably will want to know what is causing it. Goldorado Animal Hospital knows it can be hard for pet owners to know when to worry about these things, and we are here to help. Red eyes in dogs is never normal, and it’s always a good idea to call us whenever you notice a problem with your pet’s eyes.

Why Red Eyes in Dogs Happen

There are quite a few things that can contribute to red eyes in dogs. While pulling an all-nighter is not a likely culprit, we do see a varied number of causes from serious to totally benign.

Causes of eye redness can include:

Irritation — When a pet’s (or person’s) eyes are irritated by wind, chemicals, or allergens, the white part (sclera) can become reddened. This can also happen if the eye becomes dry due to inadequate tear production or increased pressure within the eye itself.

Conjunctivitis — When the tissues around the eye become infected or otherwise irritated, they often swell. This can cause overall redness around the eye, often accompanied by discharge.

Hyphema/flare — The eye contains two fluid-filled chambers. Sometimes redness in the form of blood or other inflammatory cells will appear inside the eye secondary to trauma or disease.

Corneal damage — When the cornea (surface of the eye) is damaged, the body often tries to put a band-aid over it. Blood vessels may try to grow to bring healing materials to the damaged area and sometimes a patch of granulation tissue will form over the area.

Nictitating membrane — Dogs (and cats) have a third eyelid, also called the nictitating membrane in the corner of their eye. When the eye is irritated, we often see this eyelid come up to cover it. Occasionally the tear-producing gland that lives on this eyelid will pop up and become visible. This condition is commonly known as cherry eye.

When Red Eyes in Dogs are Worrisome

In the veterinary field we commonly say that eye problems are always a pet emergency. This is because so many ocular issues appear similarly and it can be hard to tell the minor ones from those that can go downhill very quickly.

The eye is a very sensitive organ. In general we recommend scheduling an appointment ASAP for ocular issues. It is especially important that we see your pet right away if:

  • Your pet is pawing/rubbing at one or both eyes
  • The eye(s) is unable to open fully
  • There is discharge or excessive tearing
  • The third eyelid is elevated
  • There appears to be swelling
  • Your pet’s vision seems to be affected
  • Your pet appears to be in pain

Eye problems are well known to go from bad to worse in a very short time span. A thorough ophthalmic assessment is needed in order to properly diagnose what is happening so that the appropriate treatment can be started.

The eyes are the window to the soul, and their care is so important to your pet’s health. Red eyes in dogs aren’t necessarily cause for panic, but quick action to have the problem evaluated is key to keeping your pup happy and comfortable.

Watch the video: Bloodshot Eyes Red Eyes Causes and Treatments

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