Bloodshot Eyes in Dogs: Common Causes

For dog owners, the health and safety of their pups is often at the forefront of the mind. This can be even truer if you notice something amiss, something like red and swollen eyes.

Red eyes in dogs can simply be a sign of slight discomfort with a speedy recovery, or it could be a sign of a serious acute or underlying chronic health condition. So maybe you’ve already noticed redness to your dog’s eye and want to learn what to do. Or perhaps you have read some internet horror stories and just want to be prepared.

Either way, this article will bring clarity to your concern by detailing:

  • Signs & symptoms of your dog having an eye problem (and how to perform an at-home exam).
  • The most common causes of bloodshot eyes in dogs.
  • Likely ways your vet will diagnose and treat your dog.
  • Ways to prevent and mitigate the risk of your dog getting red and irritated eyes

Bloodshot & Beyond: Other Signs Your Dog Has Irritated Eyes

If you notice your dog’s eyes are a bit bloodshot, you can keep an eye out for some of these other signs and symptoms. In other cases, some of these signs and symptoms may be more visible, and cue you in to look closer and notice redness to his eyes.

Here are some things to watch out for if you fear your dog is suffering from an eye issue:

  • Excessive squinting or blinking:  Squinting and blinking may be a sign of a scratch or other physical damage done to the eyeball, or something worse. In addition, your dog may hold its eyes closed for long periods of time. Usually, these symptoms usually come with teary and watery eyes.
  • Rubbing or pawing eyes: This is a similar reaction to squinting and blinking, and is usually a sign your dog is suffering from some form of discomfort or pain. Do a visual inspection (see instructions below) to see if your dog has anything stuck in his eye. If he continues rubbing or pawing at his eye, call your vet.
  • Watery or tear-stained eyes: Your dog’s eyes may not be red and swollen, but excessive tear production or watery eyes can be a sign of an issue. One thing to look out for is water or tear-stains on the fur around his eyes. This can be a sign of blocked tear ducts and should be addressed by your vet.
  • Mucus or discharge around the eyes: Just like in humans, “eye-boogers” are normal for dogs, but an excess of “crusty gunk” around the eyes could be a sign of something wrong. If there’s pus or a mucus-like substance that’s discolored, this is a sign of canine eye infection. If you notice this, take your dog to the vet as soon as possible.

After speaking with an animal health care professional to see what they had to say about giving your dog an at-home eye exam. Detailed below is the medical-ese, put it in bullet format to make it super easy for you to follow:

  1. First, make sure you’re in a bright, well-lit room. Bonus points if it’s a room your dog is familiar with. The last thing you want on your hands is a fight with a squirming pup.
  2. With clean hands, gently lift your dog’s chin up and look into his eyes. The white part of his eyes should be clear and vivid. If there’s any discoloration or milkiness, it could be a sign of a problem.
  3. Peel your dogs eyelids back with your thumbs (again, remember to use clean hands) and look at the membrane underneath the eyelid. It should be pink. Not red. Not white. If it’s swollen or discolored, call your vet.

Common Causes of Bloodshot Eyes in Dogs

As mentioned earlier, red and bloodshot eyes can be caused by a myriad of reasons. The following is just a list of common ones you may encounter.

It’s important to be armed with this information so you can communicate with your vet and come to the best decision on how to proceed.
However, you shouldn’t be the one diagnosing your dog. You may suspect one of the following factors is the problem, but until you bring your dog into the vet to be tested, you won’t know for sure.

Irritants & Pollution

A common and often underlooked cause of bloodshot eyes in dogs is environmental pollutants and chemical irritants.

These can include cigarette smoke, perfumes, air fresheners, industrial pollution, and more. Always be aware of the air quality in your home and the places you take your dog.

In addition, remain aware of what chemicals you’re using to clean your home and how that affects your dog.


Just like in humans, dogs can suffer from itchy, dry, and bloodshot eyes if afflicted by allergies.

This can be due to allergies to foods or environmental elements such as dust and pollen. If you think your dog is suffering due to allergies, remove the offending source if possible.

Injury or Trauma to Eye

Many dogs are the ‘rough and tumble’ type, meaning they’ll chase the squirrel now and worry about safety later.

This means your pup can have a whole lot of fun getting his energy out, but it can also give dog-parents a lot of stress.
For example, a dog running through a densely wooded or chaparral-like area may get scratched by a low hanging tree branch or bush.

Similarly, fighting other animals (such as cats, dogs, or coyotes) or falling can cause damage to the eye. If your dog is the rambunctious type, try to give him a quick eye exam after any dangerous activity.

Canine Cherry Eye

Many people don’t know that dogs have a third eyelid in the corner of their eye. This third eyelid protects their eye and normally remains hidden.

However, some dogs can have a genetic disorder that weakens the ligaments holding the third eyelid in place.

This results in a condition called cherry eye, where the eyelid pops up and look like a cherry in the corner of the eye. If this occurs, surgery is generally required to fix it.

Dry Eye in Dogs

It’s common knowledge that red, bloodshot eyes are often caused by excessive dryness. Dry eyes in dogs can be caused by a number of factors.

One common cause is a lack of tear production. This can be due to blocked tear ducts, or a condition known as immune-mediated adenitis.

Immune-mediated adenitis causes damage to the tissues responsible for forming the water portion of a tear.

Pink Eye Conjunctivitis

Pink eye, also called conjunctivitis, can affect dogs just like humans. Pink eye is caused by inflammation to the conjunctiva – that pink membrane surrounding the inside of your dog’s eyelids.

Pink eye can be caused by environmental irritants, but can also be caused by an infection. Pink eye is cause for taking your dog to the vet.

Hemorrhages in the Eye

When you hear the word hemorrhage, you probably think of something catastrophic. That’s because a lot of time hemorrhages can occur in the brain.

But hemorrhages in the eyes are generally harmless. However, they can cause your dog’s eyes to become red and bloodshot.

Simply, hemorrhage is a burst blood vessel. If it looks like your dog may have a hemorrhage in his eye, call your vet.

Glaucoma, Uveitis, Corneal Ulcers

As mentioned, there are tons of conditions (both rare and common) that can result in redness to your dog’s eyes. The three conditions listed above are just for example.

Other causes could be due to cancer or a tumor in the eye. Really, if your dog has been suffering from bloodshot eyes for a period of time, you need to take them to the vet as soon as possible.

How Your Vet Will Diagnose & Treat Your Dog

So you’ve decided to take your dog to the vet and are wondering what to expect? Or maybe you just want to be prepared for the future.

Here’s a quick rundown of the tests and treatments your vet may recommend:

  • Visual exam: First and foremost, your vet will want to visually inspect your dog’s eye. This will allow them to weed out potential diagnoses and will give them insight into what tests to run. Sometimes, a visual exam is all that’s required for an accurate diagnosis. Other times, your vet will ask to run one or more of the following tests.
  • Blood, urine, electrolyte screenings: If your vet suspects an underlying health condition is causing your dog’s bloodshot eyes (such as cancer or an autoimmune disorder), they’ll run a blood chemical panel, a urinalysis, and an electrolyte screening. Depending on the results, they may ask to run more.
  • Schirmer tear test: If your vet suspects your dog’s red eyes are due to improper tear production or blocked tear ducts, they’ll run this test.
  • Fluorescein stain test: Your vet will stain your dog’s eyes with a non-harmful dye. This allows your vet to see scratches, injuries, and other structural defects that are otherwise invisible to the naked eye.

Mitigating the Risk

So you may be wondering, “How exactly should I keep my dog’s eyes safe?” Here a few things to watch out for:

  • Rough & tumble play: Let’s face it, certain breeds like to play rough. Really rough. And though you want to let your dog have fun and get out his energy, it’s important to remember that the eyes are vulnerable and can be scratched or damaged during extremely rough play. Make sure to keep an eye on your dog and check him after every play session. Also, remember not to let rough play escalate into a fight.
  • Running through vegetation: As mentioned above, dogs often run or walk into low hanging trees or bushes, causing scratches to their eyes. But other less obvious things can also cause damage to your dog’s eyes. Even running through tall grasses can cause minor cuts and irritation. Usually, this is harmless, but be sure to examine your dog’s eyes after walking through nature.
  • Car rides: Though enjoyable for your dog, letting your pooch hang his head out the car window while driving is a leading cause of eye trauma.
  • Genetics: It’s true, certain breeds are more susceptible to eye problems. For example, bloodhounds & basset hounds often suffer from irritation caused by their eyelashes rubbing against their eyeballs. Other breeds that face similar problems are poodles & cocker spaniels (due to lack of tear production), and short-nosed breeds, such as pugs.


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