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Brown streaks on the cheeks of little dogs is a common sight. When
tears overflow from the eyes, they run down the face, creating
wetness that provides the perfect environment for bacterial growth.
As bacteria replicate, they cause skin irritation and produce
pigment that stains the hair brown. In dark-coated dogs, this colour
change is of little consequence, but in white dogs, tear staining is
obvious.
There are two causes of tear staining. The first is tear-duct
blockage. In the normal canine eye, tears leave the eye via two
small openings (called “puncta”), one in the upper eyelid and the
other in the lower. Once through the puncta, tear fluid enters the
tear duct that carries it to the nose. This anatomy is the same in
people – it’s why your nose drips when you cry.
Some dogs are born with “imperforate puncta” – a condition that
prevents tears from entering the tear ducts. According to Michael
Zigler, a veterinary ophthalmologist practicing in Oakville, Ont.,
the incidence of this condition can be as high as two per cent in
some small dog breeds. Imperforate puncta can be surgically opened
but success depends on the rest of the tear-duct system being
intact.
Many tear-stained dogs have a subtle eversion (turning out) of the
lower eyelid, which compresses the puncta, preventing normal tear
drainage. Surgical correction of the eyelids can reverse tear
overflow in these cases.
The second cause is excess tear production – too much volume for
normal tear ducts to handle. Any eyelid deformity that causes
chronic eye irritation (rubbing on the eye surface), such as an
inverted eyelid or extra eyelashes along the edge of the eyelid,
stimulates increased tear production. Many of these conditions can
be corrected surgically.
In
most dogs, a cause for tear staining can be found with a careful
examination of the eyelids and tear-duct system. Unfortunately, it’s
often a combination of factors that leads to tear overflow and
subsequent staining. Treatment may be frustrating or unsuccessful.
Ultimately, the owner of a dog with tear staining needs to
diligently keep the hair clean.
Zigler recommends trimming the hair regularly, cleaning the skin
with a water-soaked cotton ball, then blotting it dry. He also
suggests applying Zincofax, an ointment used for diaper rash, to
help control skin irritation.
The authors of the book Small Animal Dermatology recommend the
application of hydrogen peroxide to stained hair. Because the
stained area is close to the eyes, the hair should be carefully
“painted” with a cotton applicator (Q-tip) soaked with peroxide.
Alternatively, a commercial product that bleaches tear-stained hair
back to its natural white colour can be used on a regular basis.
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