Pink eye in dogs, technically called conjunctivitis, is a common health problem characterized by redness of the eye. It is considered the most common among all problems that affect canine eyes. Like conjunctivitis in humans, pink eye in dogs is not painful. It also has various possible causes and severity, and therefore has different appropriate treatments. However, this condition is usually not very serious, and while there are little precautions that can be taken, its occurrence can be prevented.

Conjunctivitis can be simply defined as the inflammation of the conjunctiva, a membrane that protects the surface of eyeballs and the back of the eyelids. The conjunctival membrane also covers the cornea. The inflammation can be due to different factors, and pink eye itself can point to different health problems in a dog. For instance, if the condition is present only in one eye (called unilateral), then the redness may only be due to a foreign object that is irritating the conjunctiva. However, if both eyes appear red (multilateral), then there may be a more serious problem, such as allergy or a systemic disease.

Causes and Types of Pink eye in dogs

Because pink eye in dogs refers loosely to redness in either or both eyes, the condition can be due to various causes. In puppies, redness of the eyes is sometimes observed as they begin to open their eyes. This type of pink eye—called neonatal conjunctivitis—may occur to puppies between the ages of 10 to 14 days. Neonatal conjunctivitis is characterized by swollen or bulging eyelids and discharge with pus.

Pink Eye In Dogs - Signs, Symptoms, Diagnosis, Treatment, Prevention, Causes and TypesCredit: PixabayAs for the pink eye caused by conjunctival inflammation, the condition can be classified into three convenient types: serous, follicular and purulent. This classification is based on the different symptoms presented by the three types, as well as the factors the commonly cause them.

Serous conjunctivitis is the mild type, characterized by pinkish eyes that appear a little swollen. Dogs with this type of conjunctivitis have clear and watery discharge on their eyes. It is typically caused by physical irritation brought by certain substances or objects. Wind, dust, even dog fur can serve as irritants that inflame the eyes. Allergens also cause conjunctivitis, and when it does, the condition is aptly termed allergic conjunctivitis. As allergies go, this type also makes the affected eye itchy. Other than allergens and harsh, foreign objects, some viral agents can cause serous conjunctivitis. In particular, viruses make the eyes produce a clear discharge that is characteristic of this type of pink eye in dogs.

Also called mucoid conjunctivitis, follicular conjunctivitis is another type of pink eye that is characterized by a mucoid discharge. This discharge is due to the reaction of the mucous glands found on the underside of the dog's third eyelid (nictitating membrane) to certain irritants. The reaction, which can also be caused by infection (bacterial, fungal or viral), creates a rough surface on the eye which then triggers the production of mucus. Irritants include dust, smoke, chemicals and products like shampoo.
Pink Eye In Dogs - Signs, Symptoms, Diagnosis, TreatmentCredit: Pixabay
The last type of conjunctivitis based on discharge is purulent conjunctivitis. This one is essentially serous conjunctivitis that has become infected and is therefore a serious case of pink eye. The characteristic discharge of purulent conjunctivitis contains both mucus and pus. This secretion is often thick in consistency and tends to crust the eyelids. The infection is typically bacterial and is specifically caused by Staphylococcus and Streptococcus bacteria.

Aside from these common causes, other disorders and predispositions make a dog vulnerable to pink eye. Keratoconjunctivitis sicca (KCS), for instance, is a condition where the eye produces inadequate amounts of tears. With the eyes being dry, irritation and infection easily occur, thus causing conjunctivitis. Glaucoma, a disorder wherein there is an increased amount of pressure in the eye, can also increase the chance of pink eye in dogs. Reddening of the eyes is also likely if a dog encounters a physical trauma in the eye or if a foreign body enters the eye. The likelihood of the condition is also increased if the dog has eye abnormalities or if its body structure makes it vulnerable to irritants and infectious agents.

Signs and Symptoms

The signs and symptoms of conjunctivitis is dogs are essentially similar to that of the distinguishing features of each type of pink eye discussed above. In general, though, conjunctivitis is characterized by redness, swelling and moistening of either or both eyes. There may also be changes in the dog's behavior. In particular, an affected dog may show irritability and may also paw on their eyes to scratch an itch that is often associated with pink eye. Squinting or excessive blinking are also indication of a problem in a dog's eyes. It is worth noting, however, that signs and symptoms vary from case to case.

Diagnosis and Treatment

Dog owners who suspect their dog of having conjunctivitis must at once set an appointment to a veterinarian. This is especially true for cases that are not mild. Either way, sending a dog to the vet is the safest and best way to confirm the condition. Diagnosis is mostly observational, with the veterinarian determining the distinguishing features of the dog's condition and identifying whether it fits the classical symptoms of any of the conjunctivitis types mentioned above. For cases where the discharge is mucoid, a Schirmer Tear Test may be administered to rule out KCS and confirm follicular conjunctivitis. A test called fluorescein stain may also be necessary to check whether the symptoms indicate a more serious eye condition.

One course of treatment of pink eye in dogs is to correct the underlying condition that has caused the conjunctivitis. This is true for cases that are due to glaucoma or KCS and in instances where the problem is caused by a structural abnormality in the eye. However, in general, pink eye is addressed depending on its severity. Mild serous conjunctivitis, for example, can be taken care of at home. Saline eyewash available at drug stores can be used to treat such a case. Follicular conjunctivitis, especially when mild, can be treated with antibiotics and eye ointments that one can obtain from a veterinarian.
Prevention of Pink Eye In DogsCredit: Pixabay
For cases that are more serious, additional procedures are often necessary. Resistant follicular conjunctivitis, for instance, is addressed through chemical cauterization which destroys the follicles that irritate the eyes. Purulent conjunctivitis, on the other hand, is treated by removing the mucus and pus that have built up in the eyes. The crusts that form due to these substances are also cleared using sterile eyewash. This type of pink eye is also treated with the use of antibiotics, although the topical kind is applied in such case. In treating purulent conjunctivitis, one must not use corticosteroids as these medications inhibit the natural healing process following an infection. As for neonatal conjunctivitis, professional help must be sought, as this type of pink eye in dogs can lead to permanent blindness when not dealt with properly.


Because conjunctivitis is a multifactor condition, its preventive measures are rather indefinite. There are no guaranteed ways to prevent pink eye in dogs, although there are a number of measures that can minimize a dog's chances of acquiring the condition. For one, an owner can identify allergens to which the dog is sensitive to. With this information, a dog can be kept away from substances that can trigger a response, which may include conjunctivitis. It also helps to keep the dog away from objects and products that can prove irritating to the dog's eyes, such as harsh shampoos. Keeping a dog's hair groomed, especially around the eye area can also help reduce the risks of conjunctivitis.