Adrienne is a certified dog trainer and former veterinarian assistant who partners with some of the best veterinarians worldwide.
When a dog develops eye discharge, commonly referred to as "boogers," it's quite normal for dog owners to feel alarmed about it, especially if they appear of a different color.
Other dog owners, on the other hand, may be bothered by them, mostly because they're an unpleasant sight.
Those engaging in worrisome thinking can be right. In some cases, the gunk can indicate an underlying eye issue based on the type of discharge and amount, points out veterinarian Dr. Ivana.
In this article, Dr. Ivana Crnec, a practicing veterinarian graduate of the University Sv. Kliment Ohridski’s Faculty of Veterinary Medicine in Bitola, Republic of Macedonia, will cover the following:
- Whether eye discharge in dogs is normal
- Types of eye discharge that indicate problems
- The common underlying causes of eye discharge
- Some eye colors indicating trouble
- Underlying problems known for causing eye discharge
Is Eye Discharge in Dogs Normal?
Yes, small and infrequent amounts of eye discharge are normal.
For your dog's eye to function normally, it needs to be lubricated. This is where tears kick in. Tears have several roles—they nourish the eye and provide oxygen, hydrate the outer layers, and help remove debris from the surface.
The tears are produced in tear glands. When formed, they wash the eye and then drain via the tear ducts located at the eye’s corner.
Since the dog’s eyes are constantly exposed to the environment, it is expected for debris to accumulate in the corner of the eye.
The debris mixes with tears waiting to be drained and forms eye discharge—more popularly known as boogers, gunk, goop, or crust.
When Is Eye Discharge in Dogs Normal?
Eye discharge is normal when present in small amounts and in specific situations.
For example, a small amount of light brownish boogers in the morning is normal. It is also normal if this type of eye gunk is present when a dog wakes up from a nap.
Based on the dog’s facial anatomy and hygiene habits, these morning gunks are more pronounced in some dogs than others.
Namely, Boxers, Pugs, and other breeds with large eyes and short snouts are likely to experience copious eye leakage.
Similarly, Cocker Spaniels and Poodles are predisposed to blocked tear ducts. Once the tear ducts are blocked, the tears accumulate, resulting in a more intense formation of eye gunks and discharge.
In addition to facial and eye anatomy, another risk factor for increased eye discharge presence in dogs is allergies. Obviously, dogs with allergies experience higher eye leakage and are more likely to form boogers under normal circumstances.
As the owner, you will be able to notice a pattern in the presence of eye discharge in your dog. That way, you will know when the boogers are normal and when they are indicative of an underlying issue.
What Colors Can The Eye Discharge Be?
The eye discharge can be clear, white, dark red, brown, yellow, or green. The color is important as it often indicates a specific problem. Let’s take a closer look at the different colors and their meaning.
Clear and Watery Eye Discharge
Usually, this type of discharge is caused by allergies and common environmental irritants, such as dust or pollen.
Clear and watery discharge can also be triggered by blunt trauma to the eye, superficial eye wounds, and blocked tear ducts.
Watery eye discharge is normal in brachycephalic breeds (Pugs, Boxers, and Pekingese Dogs) with bulging eyes.
White Eye Discharge
White eye discharge has two leading causes—allergies and issues with the eye anatomy.
Common problems resulting in white eye discharge are dry eye (also known as keratoconjunctivitis sicca or KCS) and conjunctivitis (inflammation of the eye’s surrounding tissues).
Dark Red and Brown Eye Discharge
This is usually more common in the form of stains rather than typical discharge.
It occurs in dogs with chronic tearing caused by blocked tear ducts or abnormal eye anatomy.
Either way, the unique color is due to prolonged exposure to tear staining. The staining itself is the result of a substance called porphyrin.
Porphyrin is normally found in tears and is colorless. However, when exposed to oxygen, it turns red or brown.
Yellow and Green Eye Discharge
The most common cause of yellow or green eye discharge is a bacterial infection of the eye.
These eye discharge colors can also be seen in dogs with corneal ulcers and infected eye wounds.
The presence of yellow or green eye discharge is a red flag and indicates the dog needs immediate veterinary attention.
What Causes Eye Discharge in Dogs?
With the eye discharge colors covered, it is time we discuss the most common underlying causes and say a word or two about possible treatment options.
1. Eye Infection (Conjunctivitis)
Conjunctivitis is inflammation of the lining of the eye and is a widespread issue in dogs. It can be triggered by allergies, birth defects, tear duct issues, injuries, infectious diseases (e.g., distemper), or even eye tumors.
If left untreated, conjunctivitis spreads and can result in permanent eye damage. Since there are many different causes of eye infection, the exact treatment would depend on the specific trigger.
2. Dry Eye (Keratoconjunctivitis sicca)
Dry eye or keratoconjunctivitis sicca (KCS) is a specific type of eye infection in which the tear glands do not produce tears. As a result, the eye cannot be lubricated and becomes dry and inflamed.
This can lead to infections, permanent eye damage, and in severe cases, even vision loss. Luckily, KCS is easy to diagnose and, with prompt and adequate treatment, easy to manage.
3. Eye Injury and Foreign Objects
Superficial eye injuries and foreign objects are common in dogs and always manifest with increased eye discharge.
In such cases, the increased production of eye discharge is a normal defense mechanism—the eye produces more tears to clean the wound or flush the foreign object away.
However, if the eye discharge changes color or becomes pronounced, it is imperative to see the vet.
4. Cherry Eye
Cherry eye is a condition in which the gland on the back of the third eyelid (also known as the nictitating membrane) protrudes and turns into a swollen and inflamed mass resembling a cherry.
Normally, the gland is held in place by a ligament. However, if the ligament tears, the gland will pop up. This is more common in brachycephalic breeds.
Cherry eye is not painful, but it is irritating and increases the risk of eye infections.
Dogs with cherry eyes require corrective surgery in which the gland is repositioned and fixed in its normal anatomical place.
5. Entropion and Ectropion
Entropion and ectropion are inherited eyelid abnormalities.
Entropion indicates inward inverted eyelids and is more common in dogs with excess skin folds, such as Shar-Peis and Chow Chows. As a result, the eyelashes are constantly irritating the cornea.
Dogs with ectropion have the opposite problem—outward inverted eyelids, which prevent the eye from closing correctly. The condition is common in Bloodhounds, Cocker Spaniels, Mastiffs, and Dogue de Bordeaux.
Both conditions are easy to solve through a simple surgical procedure.
6. Corneal Ulcers
Corneal ulcer is the medical term for eye sores, which can be either superficial or deep. In both cases, they are painful and, if left untreated, can have long-term consequences.
Corneal ulcers can be caused by eye trauma, foreign bodies, lack of tear production, etc. A dog with a corneal ulcer will be sensitive to light, squint frequently, and rub the eye with its paws.
Depending on the severity of the ulcer, the treatment can involve medications such as antibiotics and anti-inflammatories or surgery.
7. Eye Tumors
Eye tumors in dogs are not common. However, if they occur, they can trigger a range of symptoms, including increased tearing and eye discharge formation.
Some eye tumors are benign and can be managed, while others are malignant and have a poor prognosis.
Cataracts are clouding of the lens and are usually an inherited condition. However, canine cataracts can also be the result of diabetes mellitus.
It is common in Boston Terriers, French Poodles, Labrador Retrievers, American Cocker Spaniels, and Welsh Springer Spaniels.
If caught early, the vet can perform surgery to remove cataracts and save the dog’s vision. However, if left untreated, it leads to vision impairment and eventually vision loss.
9. Canine Glaucoma
Canine glaucoma is a serious condition that manifests with increased pressure within the eye. It can be caused by lens damage, inflammation, infections, tumors, and bleeding inside the eye.
Glaucoma is an extremely painful condition and manifests with bulging of the affected eye, eye clouding, and excess tearing.
Based on the severity of the situation, the vet may prescribe medications or, in more pronounced cases, recommend the removal of the eyeball.
All in all, eye discharge is normal when in small amounts and clear or watery.
However, the presence of copious eye discharge or dark-colored discharge indicates an underlying issue and requires veterinary attention.
The dog’s eyes are sensitive structures. Therefore all issues need to be addressed fast. When it comes to eye problems in dogs, things can go from bad to worse in a matter of hours.
If your dog is experiencing unusual eye discharge or other eye issues, call your trusted veterinarian and schedule a visit.
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.
© 2022 Adrienne Farricelli