What Causes Excessive Tear Staining in Dogs?

Sometimes scientific terminology does more than just baffle people.

In its own neat way, science can sometimes step in and use just 1 word to describe a condition instead of 6. Hence “excessive tear staining of the eyes” is perhaps better known as epiphora.

(Strictly speaking, epiphora actually refers to the tear overflow causing the staining, but there we are -- nothing’s perfect).

Many people with white dogs, such as the maltese, are familiar with the rusty-colored mark streaking down their pets’ faces from the inner corner of the eye. The rust color is formed when tear fluid is exposed to the air for a prolonged period of time.

Tears contain pigments called porphyrins, and just like the flesh of a cut apple that turns brown, porphyrins oxidize and cause brown discoloration.

A pertinent question to ask is why the tears overflow in the first place. The answer is that usually the tear ducts are too small or even absent -- the natural tear fluid can’t drain away via the tear ducts and instead spills over the face.

Symptoms

Signs include rust-colored marks running from the inner corner of the eye down the face. Sometimes the fur is visibly wet at the corner of the eye.

What Causes Tear Stains?

The staining arises because tears have spilled over the eyelid. This can happen as the eyes water heavily, such as if the pet has been in a wind or has an eye infection. More common is that the tear duct is too narrow to drain away the tear fluid, causing tears to spill over onto the cheek.

Narrow or absent tear ducts are often a congenital condition associated with many small breeds such as the miniature poodle, shih tzu, Bichon Frise, pug and Pekingese.

Diagnosis

One way to test the theory that the tear ducts aren’t doing their job is to put drops of a special ophthalmic dye called fluoresceininto the eye.

Normally, the orange dye would drain away via the tear ducts and turn green. Thus the veterinarian looks inside the dog’s nostril and upper lip for signs of green dye. What usually happens with tear overflow is that the dye simply spills over the face, nicely demonstrating how the tear ducts are not up to the task.

Treating Epiphora in Dogs

Treatment is difficult and ranges from flushing the tear ducts to try and unblock them to a surgical procedure to artificially create new tear ducts. The latter, however, is not without complications, not least of which is that scar tissue forms as the body heals, and this narrows the newly formed duct and prevents it from working.

Often, it is a matter of control rather than cure, and wiping the face as soon as you see eye gloop appear.

http://youtu.be/H3b2hKWME-g

Prevention

Unless flushing the tear ducts relieves an obstruction, it is difficult -- if not impossible -- to prevent tear staining.

References

• “Epiphora associated with dacryops in a dog.” Grahn & Mason. JAAHA, 31: 15.
• “Epiphora associated with canaliculops in a dog.” Gerding. JAAHA, 27: 424.

This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Dec. 17, 2018.