Dog Tear Stains — Why They Happen and How to Reduce Them

Why the colour is reddish brown

The rust-coloured mark under the eye comes from porphyrin, a pigment carried in tears. Porphyrin is an iron-containing by-product the body makes when it breaks down red blood cells, and it leaves the body in tears, saliva, bile and urine. When it sits on fur and dries, it sets into that characteristic reddish brown. It is the same reason a dog who licks their paws or lips constantly ends up with matching stains there — saliva carries porphyrin too.

So tear staining is not caused by a sudden surge of pigment. It is caused by tears staying on the face too long. A healthy eye produces tears continuously and drains an equal amount through tiny openings at the inner corner of the eyelids called puncta, down the nasolacrimal duct and into the nose. When that plumbing works, nothing spills. When the eye makes more than the duct can take, or when the duct itself is narrow or blocked, the surplus runs over the eyelid rim and pools in the same spot day after day. Veterinary medicine calls that overflow epiphora.

How visible it is varies a lot between dogs. On a light coat — Maltese, Bichon, Poodle — even faint staining shows plainly, while the same amount of overflow can be invisible on a black dog. And flat-faced breeds with prominent eyes, such as Shih Tzus, Pekingese and Pugs, spill tears for structural reasons: the geometry of the eyelids and the globe simply does not funnel tears toward the puncta well. In other words, "the dog whose stains show" and "the dog whose eyes actually water too much" overlap but are not the same group. That distinction is where the rest of this article starts.

One important fact: published veterinary sources agree that a large share of dogs with tear stains have no underlying eye disease at all. For many dogs this really is closer to a cosmetic issue. But not all of them — and the ones that do need treatment are mixed in with the rest. That is why the order of steps matters.

Two broad causes — too many tears, or tears that cannot leave

It looks complicated, but the causes sort into two groups. (1) The eye is irritated and producing more tears than normal, or (2) production is normal but the drainage route is not working. What you do about it differs completely, so this is the first split to make.

The two columns to read closely are "one eye or both" and "since when". If both eyes have been equally damp since puppyhood, the cause is most likely structural, and it usually does not threaten sight or health. If a dog who was fine suddenly starts watering — especially in only one eye — assume something has happened to that eye. Corneal injuries, grass seeds, eyelid growths and duct obstruction all begin exactly that way.

There is one cause people routinely miss: teeth. Infection at the root tip of an upper canine or molar (a tooth root abscess) can press on or inflame the nasolacrimal duct running just above it, and drainage suffers. If tear staining arrived alongside worse breath, swelling on one side of the face, or a reluctance to chew hard things, the mouth needs checking as well as the eye. Ears matter too: a dog with chronic otitis is dealing with inflammation across the whole face, and that can feed into the eyes.

In summer, causes tend to stack. Pollen and mould spores drive allergies, air conditioning and fans dry the eye surface, and sand or grass seeds get in on walks. Add humidity and the permanently damp fur under the eye becomes a good home for bacteria and yeast — so the same volume of tears progresses to smell and skin inflammation much faster than it would in winter.

Cosmetic, or something that needs a vet?

At home you really only need to answer one question: is this a grooming issue, or is my dog uncomfortable? The table below sorts most cases.

That last row is the one most often overlooked. When you think of tear stains as a colour problem, it is easy to miss that the skin underneath is permanently wet. Damp skin held in a fold is ideal territory for bacteria and yeast, and over time that becomes moist dermatitis — red, smelly, with hair loss. At that point reducing the tears is no longer enough on its own; the skin needs treating too. If your dog flinches when you touch under the eye, or the face has a sour smell, you may already be there. When face, paws and ears are itchy together, the causes described in dog skin problems and itching may be tangled up in it as well.

Everything here is general guidance. An actual diagnosis has to come from a veterinarian. The same "watering more than usual" means different things depending on the dog's age, breed and existing conditions. Eyes in particular can deteriorate badly within a day or two, so when there are signs of pain, a phone call beats more reading.

What the clinic will actually check

A tear-stain consultation usually narrows things down in roughly this order. Knowing what each step is for makes the conversation much easier to follow.

• Eyelid and lash examination — under magnification, looking for an eyelid rolling inward or lashes touching the cornea. A good share of cases are solved right here.
• Fluorescein stain — checks the cornea for scratches and ulcers. The same dye doubles as the Jones test: the vet watches for it to travel down the duct and appear at the nose or in the mouth. Sources describe suspecting an obstruction if no dye appears within about 5–10 minutes, though a negative result alone does not confirm a blockage.
• Schirmer tear test — despite the topic, this looks for tears that are insufficient: dry eye (keratoconjunctivitis sicca). Severe dryness can trigger reflex tearing that looks like too many tears, so it has to be ruled out.
• Tonometry — measures pressure inside the eye to rule out glaucoma. High priority whenever the eye looks painful.
• Nasolacrimal flush — if the drainage route looks blocked, a fine cannula is passed into the punctum and sterile saline is used to flush it. Dogs cannot hold still for this, so it generally requires sedation or general anaesthesia.
• Imaging and an oral exam — for repeated blockages, or one-sided onset in an older dog, imaging may be added to look for a tumour or a tooth root abscess.

Treatment then follows the cause. Correcting lash problems or entropion removes the irritation and the tearing drops on its own; allergies are managed with antihistamines or avoidance; infection gets topical antibiotics; an obstruction may be flushed or stented. But when the cause is something that cannot be corrected — such as a flat-faced skull — the goal shifts from eliminating the problem to keeping it low. In those dogs, what happens at home ends up mattering more than what happens at the clinic.

The home routine — wipe, dry, trim

The principle is simple: cut down the time tears spend sitting on the face. The aim is not to remove colour but to stop new colour going in.

• Wipe twice a day with warm water or sterile saline. Use gauze or a cotton pad, working gently from the inner corner outward. Do not let liquid run into the eye, and never use the same surface on both eyes.
• Then dry it. This is the step that matters most and the one that gets skipped. Fur left damp is a better environment for bacteria than it was before you started. Press the area dry with clean gauze, and if your dog tolerates it, a brief pass with a dryer on low heat from a distance.
• Keep the hair short around the eyes. Trimming the fringe that pokes the eye and the wet hair below it reduces both irritation and staining. If scissors near the face make you nervous, ask the groomer to take it short under the eyes.
• Swap plastic bowls. Scratched plastic gives bacteria somewhere to live, and glass, ceramic or stainless steel is widely recommended instead. It is worth doing for a small dog whose face touches the bowl — but there is no evidence that this alone clears tear stains.
• Wash the water bowl daily. Fresh water matters more than what the bowl is made of. You can work out what a normal daily intake looks like for your dog's weight with the pet water intake calculator.
• Keep a record. Photograph the face once a week in the same light. Day to day you will not notice change, but side-by-side photos make it obvious whether things are improving — and they are useful at the clinic.

Diet gets blamed often. In a dog who genuinely has a food allergy, a change of diet can reduce the tearing. But not every tear stain is a food problem, and switching food repeatedly on the strength of online reviews makes the real cause harder to find. If allergy is suspected, an 8–12 week elimination trial run properly with your vet is the faster route. That trial means controlling treats as well, so it helps to plan within a daily calorie figure — the dog food portion calculator will give you one.

What is unproven, and what to avoid outright

Tear stains are highly visible, which means there is no shortage of products and folk remedies. Start by ruling out the ones that are clearly a bad idea.

• Supplements containing antibiotics — avoid. In August 2014 the US FDA issued warning letters to three companies selling tear stain products. The ingredient at issue was the antibiotic tylosin tartrate, and the FDA pointed out that tylosin is not approved for any use in dogs or cats. Once a product claims to kill bacteria or eliminate infection, regulators treat it as an unapproved drug rather than a supplement. If you see tylosin on the label, put it back.
• Hydrogen peroxide, bleaching agents, human cosmetic products — no. Far too harsh for skin millimetres from the eye. The colour may lift briefly; the dermatitis stays.
• Human eye drops — not without direction. Redness removers and steroid drops can make an existing corneal ulcer deeper. Eye medication should follow an examination of the cornea, not precede it.
• Filtered or low-iron water — the evidence is thin. The idea that iron in tap water causes tear stains circulates widely, but porphyrin is something the body makes itself while recycling red blood cells. Plenty of people report improvement after switching water; solid supporting evidence has not been established. It does no harm to try, but do not let it replace finding the actual cause.
• Probiotics, omega-3 and similar supplements — sources disagree. Some recommend them for skin barrier and inflammation generally, but the evidence that they reduce tear staining specifically is weak. If you use them, do not let them delay a diagnosis.

A last word about expectations. Fur that is already stained will not change colour. The face clears only as new hair grows in and the stained portion is trimmed off, which means visible progress takes weeks at minimum — and in a dog whose cause is structural, it may never disappear entirely. It is healthier for everyone to set the goal as "comfortable eyes and dry skin" rather than a spotless white face. And if the skin under the eyes stays wet, check inside the ears too; problems in damp places tend to travel together. There is more on that in the dog ear infection guide.

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