

dog eye infection

Story at-a-glance -

  • Sometimes eye discharge is nothing to worry about, however, it’s important to have your dog or cat examined by a veterinarian
  • The most common causes of ocular discharge in pets are trauma to the eye, eye infections, allergies, tear duct blockages and the facial construction of certain breeds

By Dr. Becker

Just like many humans, dogs and cats can collect gunk in the corners of their eyes — that slightly crusty, gooey stuff that is sometimes lovingly referred to as “eye oogies.” Technical name: ocular discharge.

Sometimes discharge from a pet’s eyes is more or less normal and nothing to worry about, but there are also times when the condition is a signal that something else is going on — something that should be investigated and addressed.

According to Dr. Kathryn Primm and veterinary journal dvm360, five of the most common causes of ocular discharge in pets include:

  1. Injuries
  2. Infections
  3. Allergies
  4. Blockages
  5. Breed conditions

Let’s take a closer look at each of these disorders/conditions, along with one other condition that causes a lot of “oogies” for many pets.

Injuries to the Eye

Trauma to your pet’s eye can result from either a blunt force injury from a flat or dull object striking the surface of the eye, injuring but not penetrating it, or a sharp force injury that results from a piercing, pointed or jagged-edged object striking the eye.

Pets can also get foreign objects lodged in their eyes, typically something found outdoors such as leaf or plant matter.

Ocular trauma is much more common in dogs than cats. Puppies and young dogs are more likely to get in the way of a cat’s claws, for example, and are also more apt to wander away from their owners and get hurt. This is also true for unsupervised intact male dogs.

Other dogs at higher risk for ocular injuries are working, hunting and outdoor dogs who run through wooded areas and brush. These dogs are also more likely to come in contact with other off-leash or wild animals, as well as vehicles.

In addition to ocular discharge and perhaps redness, a pet with a mild eye injury may blink more than usual or squint, and paw at the affected eye. If the eye trauma is serious, symptoms will be much more noticeable and can include bleeding within the eye and extreme pain.

Trauma to the eye should always prompt a visit to your veterinarian, and if your dog or cat seems to be in pain and/or the injury is severe, you should get your pet either to your vet or the nearest animal emergency hospital immediately.

Eye Infections

Indoor-outdoor cats and dogs are at greater risk for eye infections than indoor-only kitties. Symptoms of an eye infection are similar in dogs and cats. Many pets will have a green or yellow discharge from an infected eye, which is a definite sign of a problem.

Viral eye infections in cats are typically caused by the feline herpes virus, which causes redness, irritation and inflammation in the eyes. Secondary bacterial infections are also common. Once a cat acquires a herpes infection it will be lifelong, with flare-ups often brought on by stress.


With an eye infection that isn’t resolving on its own, it’s important to identify the cause so you know how best to treat it. Infections caused by a virus, a bacteria or a fungus are all handled differently. Eye infections in dogs and cats have the same root causes, however, in dogs, Lyme disease can also be a culprit.

Eye infections are either acute or recurrent. An acute infection means your pet looked fine yesterday, but today he’s squinting.

His eyes are red and irritated looking, and he may be pawing at them, in which case you should consider an E-collar to prevent him from doing permanent damage before the situation either resolves on its own, or you get him to the vet for diagnosis and treatment.



Cats and dogs with seasonal, environmental and even food allergies often have eye discharge.

If your pet is experiencing an allergic reaction to household cleaning products or air pollutants like cigarette smoke, dust or smog, his eyes may tear. Your dog or cat can also develop sensitivity to typical human allergic triggers like certain fabrics, dander and pollens from grasses and trees.

If your pet isn't eating a nutritionally balanced, species-appropriate diet, for example, if the food you feed contains grains, starchy carbs, additives and preservatives, or the same protein source day in and day out, his system may be trying to get rid of the elements in his diet his body can't properly assimilate.

Animals detox through not only their bowels, but also their eyes and ears. For some great suggestions to help an allergic pet, I recommend my video and article “Holistic Tips for Pet Allergies.”

Tear Duct Blockages

Sometimes eye discharge is the result of a problem with the way tears drain. Fortunately, a simple non-invasive test can be performed to see if your dog's or cat's eyes are draining normally.

A special stain, fluorescein, is applied to the surface of the eye. If drainage is normal, there will be evidence of the stain solution at the nostrils within a few minutes.

A healthy eye is very efficient at managing the flow of tears because the nasolacrimal duct allows the flow of tears into the nasal passages and throat. However, in animals with shallow eye sockets the eyelid space may not be deep enough to manage the quantity of tears produced.

The overflow never makes it to the drainage ducts, but instead spills over at the corners of the eyes and runs down the sides of the nose, making the pet appear as if he’s crying. Other causes for abnormal tear drainage:

  • Entropion, a condition in which your pet's eyelids are turned inward, blocking off the drainage holes.
  • In long-haired breeds, the fur can actually wick tears away from the eyes to the skin. This is especially prevalent in breeds that grow hair on the caruncle of the eye, which is the moist, pink area in the inner corner of the eyelid.
  • An infection or injury can cause scarring to drainage areas of the eye. This can sometimes be remedied by flushing the ducts with saline to re-open them. This must be done by a veterinarian and your pet will need to be sedated.
  • Certain dog breeds have a genetic predisposition to closed drainage holes, which requires surgical correction.

If your pet has a tear drainage problem that can be resolved with surgery, I recommend consulting a veterinary ophthalmologist with the training, experience and specialized equipment necessary to perform delicate eye surgery.

Breed-Related Eye Conditions

Brachycephalic breeds with pushed-in or flat faces are prone to eye problems that can cause chronic ocular discharge. In fact, it’s very common for brachys to have constant watering of the eyes or wetness around the eyes. This can be the result of the eyelids not closing effectively.

Brachys also have shallow eye sockets as discussed above, which means there’s less eyelid space available to collect the tears produced, so the excess overflows onto the face. This isn't a situation that can be repaired because it’s a result of the construction of your pet's head and face.

Dry Eye and Lid Position: Unexpected Reasons for Eye Goop

Keratoconjunctivitis sicca, or dry eye, is another reason for eye oogies that should not be overlooked. This condition causes thick, stringy mucus to accumulate on the surface of the eyes and an excessive build-up of crust in the corners of the eyes if they aren’t kept clean and lubricated. This condition can be easily diagnosed with a tear test.


If your dog or cat suddenly develops discharge from the eye, or it’s been going on for a while but hasn’t been diagnosed, it’s important to make an appointment with your veterinarian for evaluation and treatment, if necessary.

If it ends up your pet's runny eyes are simply something you both have to live with, talk with your vet about how to minimize the tearing if possible, how to protect your pet from infection as a result of a constantly wet face and steps you can take to address any tear staining.

+ Sources and References