Red Eye in Dogs: When Should I Be Concerned?

In many ways, dog eyes are very similar to human eyes. Despite the popular misconception that dogs only see in black and white, their eyes actually work in much the same way that ours do. They simply see with a more limited range of colors.

The anatomy and function are very alike with some differences which allow dogs to track light and movement better than human eyesight. Humans’ and dogs’ eyes work to adjust light, focus, and send images to the brain. It is, therefore, very important to maintain clear eyes for dogs because they are just as delicate and sensitive as our own.

Dog portrait

Red, bloodshot or swollen eyes in dogs is a clear sign that something has irritated or injured the eye. This could be an indication of several different problems ranging in severity. Eyes can become reddened due to a simple allergy or something more serious that could result in blindness or the eye ceasing to function correctly. Eye problems can be extremely uncomfortable for dogs. As a dog owner, it is essential to take responsibility for your pet’s eye health and know when to schedule a visit to the vet if necessary.


Main Causes of Red Eyes in Dogs

A number of health problems can cause your dog’s eyes to become red and irritated.

Dry Eye Syndrome

Also known as Keratoconjunctivitis Sicca (KCS), this can happen to dogs when the eye is unable to produce tears. It can become painful for your dog if left untreated. There are several causes, though the most common is due to a failure in the immune system. Symptoms include a sticky or cloudy eye, redness, and dry discharge around the eye socket.


More commonly known as pink eye, this is an itchy eye condition that causes great discomfort. Symptoms include redness, puffy eyelids, discharge, and watery eyes. The viral kind is quite contagious so if you have other pets, you should try to keep them separate.

This is also one of the common reasons why your furry friends have tear stains which is an indicative of an underlying health issue. Do check whether the food you feed them have high nutritional value to prevent dog tear stains.

Corneal Ulcers

These are painful sores that can appear on the surface on a dog’s eye. They cause lots of redness, light sensitivity, discharge, and great discomfort. These ulcers, also called Ulcerative Keratitis, usually develop after some form of injury to the eye.


One of the more alarming problems that dogs can suffer in their eyes, glaucoma can cause permanent damage including blindness. The pressure on the eye builds up because the fluid does not drain properly and causes problems with the muscle that controls lens focus and shape.

Anterior Uveitis

This is an inflammation of the front tissue (uvea) of the eyeball. Dogs can suffer symptoms such as redness, light sensitivity, excessive tears, and swelling. Without treatment, this too can cause permanent damage to your dog’s ability to see.

Other common causes of eye redness include allergies and trauma to the eye area. Redness can also be a symptom of a bacterial or viral infection in another part of the body or possibly from an underlying medical condition.

Cause For Concern?

A smiling dog

Red eyes in your dog may not be an emergency but it usually a sign of something that requires prompt attention. Although it may not seem like a big deal, it is best to get it checked by a veterinarian to make sure.

There are many reasons that your dog could develop red eyes at some point in their life. But when should you be worried? The majority of these infections or syndromes are easily treated.

Sometimes, red eyes can also develop due to simple reasons. Make sure to ask yourself the following questions before visiting the vet so that you can better inform them of the situation:

  • Has your dog recently been somewhere or doing something that could have led to an eye injury or allergic reaction?
  • Have they been playing with another dog who could have scratched their eye?
  • Have they been playing in tall grass or with branches or sticks?
  • Have they been somewhere with a high pollen count?
  • Is it possible that he or she could have gotten something in their eye?
  • Would they have been exposed to some sort of chemical or cleaning product?
  • Have they been swimming?
A dog walking in a park

And finally, also check for other symptoms that are out of the ordinary with your dog. The vet will want to take this into consideration when deciding how to proceed. The veterinarian could run any of several tests including an ophthalmologic exam, a Schirmer test, or a fluorescein eye stain to determine the problem.

It is essential that dog owners do not try to treat an eye problem without the correct expert assistance. It’s also crucial to administer any medication as instructed in order to maintain proper eye health for your dog.

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