Shih Tzus have watery eyes primarily because of their flat-faced anatomy. Their shallow eye sockets cause the eyes to protrude more than in other breeds, and the wide opening between their eyelids leaves the eye surface exposed to air, dust, and irritation. This combination means their eyes produce excess tears as a constant protective response. While some tearing is simply part of life with a Shih Tzu, certain conditions common in the breed can make it significantly worse.
How Flat-Faced Anatomy Causes Tearing
Shih Tzus belong to the brachycephalic (flat-faced) group of dogs, and their skull shape directly affects their eyes. Their orbits are narrow and shallow, which pushes the eyeballs forward into a more prominent position. Despite appearances, their eyes aren’t actually larger than other breeds’ eyes. They just sit further out from the skull, making them look bigger and leaving more of the eye surface exposed.
On top of that, Shih Tzus have an excessively wide eyelid opening, a trait called macroblepharon. Think of it this way: the eyelids can’t fully cover and protect the cornea the way they would in a dog with a longer snout and deeper-set eyes. The result is a cornea that’s constantly exposed to air, particles, and minor irritants. The eyes respond the only way they can, by producing more tears to keep the surface moist and flush out debris.
Extra Eyelashes Are Surprisingly Common
About one in five Shih Tzus has a condition called distichiasis, where extra eyelashes grow from abnormal spots along the eyelid margin. These rogue lashes sprout from the openings of tiny oil glands that normally lubricate the eye. Because those gland openings face the eyeball, the extra lashes point directly at the cornea and rub against it with every blink.
A smaller percentage of Shih Tzus (1 to 3 percent in breed screening data) have ectopic cilia, where lashes grow from the inside surface of the eyelid. These are almost always irritating. In both cases, the constant rubbing triggers excess tearing, squinting, and redness. Over time, untreated lash irritation can cause the normally clear cornea to develop tiny blood vessels, turn cloudy, or develop painful ulcers. If your Shih Tzu squints frequently, paws at one eye, or has a bluish or dull spot on the cornea, abnormal lashes are a likely culprit.
Eyelids That Roll Inward
Some Shih Tzus also deal with entropion, where part of the eyelid (often the inner corner) rolls inward so that fur and lashes press directly against the eye. This creates constant friction and irritation, and the eye responds with a steady flow of tears. Entropion is genetic in the breed, and it typically requires a minor surgical correction to reposition the eyelid so it no longer contacts the cornea.
Allergies and Environmental Irritants
Not all excessive tearing comes from anatomy. Shih Tzus, like many small breeds, can develop allergic conjunctivitis, where the tissue around the eye becomes inflamed in response to allergens. Common triggers include household dust, mold, and food sensitivities. Some dogs have a genetic tendency toward allergies (called atopy) that makes them more reactive than other dogs to everyday environmental particles.
If your Shih Tzu’s watery eyes seem to flare up seasonally or after being in certain rooms, allergies may be a contributing factor. Reducing household dust, using an air purifier, and working with your vet to identify specific triggers can help. Allergic conjunctivitis often can’t be cured entirely, but it can usually be managed well enough to keep your dog comfortable.
What the Tear Color Tells You
The color and consistency of the discharge matters. Clear, watery tears are the most common type in Shih Tzus and generally reflect irritation or the breed’s normal anatomy rather than infection. This is worth monitoring but not necessarily urgent if your dog is eating normally, acting like themselves, and not squinting or pawing at the eye.
Yellow or green discharge that has a thick, mucus-like consistency is a different story. That color shift usually signals a bacterial infection, and it warrants a vet visit, especially if it persists for more than a couple of days or if the eye appears red and swollen. A sudden change from clear to colored discharge, even in a dog whose eyes always water, is a sign that something new is going on.
The Reddish-Brown Stains Under the Eyes
If your Shih Tzu has reddish-brown streaks running down from the inner corners of the eyes, those stains come from a molecule called porphyrin. Your dog’s body produces porphyrin as a byproduct of breaking down iron, and it gets excreted through tears, saliva, and urine. On light-colored fur, the iron in porphyrin oxidizes and leaves those distinctive rusty stains. The staining itself isn’t harmful, but heavy staining signals that the eyes are producing more tears than the tear drainage system can handle.
Beyond the cosmetic issue, constant moisture in the facial folds beneath a Shih Tzu’s eyes creates a breeding ground for bacteria and yeast. The combination of friction between skin folds, trapped moisture, and poor air circulation can lead to skin fold dermatitis, a superficial infection where the skin becomes red, irritated, and sometimes smelly. Keeping the area dry through daily cleaning is the best way to prevent this.
Daily Eye Care That Helps
A quick face-grooming routine each morning goes a long way. Start by flushing the eye area with a canine saline eye wash, then use a dog-safe eye wipe to clean underneath and around each eye. This removes dried discharge and porphyrin before it has a chance to set into the fur.
For tear stain removal, you can make a simple solution at home by dissolving one tablespoon of boric acid powder in one cup of boiled distilled water. Keep it refrigerated and make a fresh batch each week. Another option is diluting a tablespoon of 3% hydrogen peroxide in eight ounces of water and applying it with a cotton ball, wiping away from the eyes rather than toward them. Pre-made dog wipes formulated for the eye area also work well and are convenient for daily use.
Whatever method you choose, avoid getting any cleaning solution directly in the eyes. Keep the routine positive with treats and calm praise so your dog doesn’t start dreading it. Consistency matters more than technique here. A gentle daily wipe prevents the moisture buildup that leads to staining and skin infections.
When Surgery Makes a Difference
For Shih Tzus with chronic tearing, corneal ulcers, or significant irritation that doesn’t respond to daily care, a procedure called medial canthoplasty can help. This surgery tightens the inner corner of the eyelid opening, reducing how much of the eye surface is exposed and improving the eyelid’s ability to protect the cornea.
In a study of brachycephalic dogs that underwent this procedure at a UK referral hospital, the results were meaningful. Among dogs with follow-up data, corneal ulceration dropped from nearly 74 percent before surgery to under 6 percent afterward. Over 70 percent of owners reported reduced eye discharge, about 68 percent noticed less eye irritation, and more than half said they needed to clean around their dog’s eyes less often. Owner satisfaction with both the clinical and cosmetic results was around 86 to 88 percent. For dogs whose watery eyes have progressed to repeated corneal ulcers or constant discomfort, the surgery can substantially improve quality of life.
For extra eyelashes causing irritation, separate procedures can remove or destroy the abnormal lash follicles, which stops the cycle of corneal rubbing, tearing, and potential scarring.
Telling Normal Tearing From a Problem
Some amount of tearing is genuinely normal for a Shih Tzu. Their anatomy guarantees it. The line between “that’s just your dog” and “something needs attention” comes down to a few practical signals: whether the discharge changes color or thickness, whether your dog starts squinting or rubbing at the eyes, whether you notice cloudiness or a bluish tint on the cornea, or whether the skin beneath the eyes stays chronically red and irritated despite regular cleaning. Any of those shifts suggests the tearing has moved beyond anatomy into active irritation or infection that needs professional evaluation.