Posted by Jamie Sinclair
on August 31, 2026
Yes, canine tear staining is genuinely common and usually harmless — reddish-brown marks under a dog's eyes are typically caused by porphyrin, an iron-containing pigment in tears that oxidises on contact with air. It's more cosmetic than medical in most cases, but it's worth knowing the genuine causes, how to remove tear stains and tear marks safely (and what not to use near the eyes), when it signals something more serious, and what the real evidence says about managing it — including a surprising, recently-published link to gut health, and where our own Probiotic Chews may realistically fit in. Puppy tear stains are especially common and usually settle down with age.
Written by Jamie Sinclair, who writes about canine health, nutrition, and everyday care for Doggy Dailies — focused on translating veterinary research and real ingredient science into practical, honest guidance UK dog owners can use.
Table of Contents
- What Is Tear Staining?
- Why Does It Happen? The Real Science
- Which Dogs Are Most Prone to Tear Staining?
- Puppy Tear Staining: Is It Different?
- A Genuine Link to Gut Health
- When It's Not Just Porphyrin
- How to Remove Tear Stains Safely
- Preventing Tear Staining Day to Day
- When to See a Vet
- FAQ
What Is Tear Staining?
Tear staining refers to the reddish-brown discolouration — sometimes called tear marks or dog eye stains — that develops in the fur beneath a dog's eyes, most noticeable on light-coloured or white coats. It's not a sign your dog has been crying — dogs don't produce emotional tears the way humans do — and in the majority of cases, it's a cosmetic issue rather than a symptom of underlying disease (PDSA).
Why Does It Happen? The Real Science
The reddish-brown colour comes from porphyrin, an iron-containing compound produced when the body breaks down red blood cells. Porphyrin is excreted through several bodily fluids, including tears, saliva, and urine. When tears containing porphyrin sit on the fur and are exposed to air, the compound oxidises, turning a reddish-brown colour that becomes more visible over time — particularly on white or pale coats (PetMD). The same pigment is why a dog that licks its paws or beard a lot ends up with rust-coloured fur there too.
In most dogs, canine tear stains aren't caused by excessive tear production at all — they're usually down to eyelid or facial structure that causes tears to spill onto the face rather than draining properly through the nasolacrimal duct, the tiny channel that normally carries tears from the eye to the nose (VCA Hospitals).
Which Dogs Are Most Prone to Tear Staining?
Certain breeds are genuinely more prone to tear staining because of their facial structure:
- Brachycephalic (flat-faced) breeds — Bulldogs, Pugs, Pekingese, and similar breeds often have shallow eye sockets and shorter tear ducts, making tears more likely to spill over
- Small and toy breeds — Bichon Frise, Maltese, Shih Tzu, and Poodles are commonly affected
- White or pale-coated dogs — staining is simply far more visible against lighter fur, even at the same tear volume as a darker-coated dog
Puppy Tear Staining: Is It Different?
Puppy tear staining is extremely common and often more noticeable than in adult dogs. Many puppies go through a phase of heavier tear staining between about 4 and 7 months, often tied to teething, and it typically settles once the adult teeth are through and facial structure matures. The same daily wiping and hygiene routine that helps adult dogs works just as well for puppy tear stains — there's usually no need for anything more intensive at this age.
A Genuine Link to Gut Health
This is genuinely new, and worth knowing: a 2026 controlled feeding study of 40 Poodles and Bichon Frises — breeds specifically predisposed to tear staining — found that dietary supplementation measurably reduced tear staining, and traced part of the mechanism to changes in gut bacteria. Dogs that improved showed a measurable increase in a specific gut bacterium (Allobaculum), which correlated with better iron and porphyrin metabolism (Zhejiang Agricultural and Forestry University, 2026, Animals).
To be clear about what this does and doesn't show: the study tested specific traditional Chinese herbal extracts, not a general probiotic, and it doesn't prove that any particular product — including our own — will reduce tear staining. What it does establish is a genuine, published, dog-specific link between gut bacteria and porphyrin metabolism, which is a real and previously under-recognised piece of the puzzle. If your dog's digestion or gut balance seems generally off alongside tear staining, our Probiotic Chews support everyday gut health — worth knowing about, but not something to treat as a proven tear-staining fix on the strength of this one study.
When It's Not Just Porphyrin
A few other causes are worth ruling out, since they need different handling:
- Yeast infection — damp fur under the eyes is a good environment for yeast, which can cause a darker, more musty-smelling stain distinct from ordinary porphyrin staining
- Blocked or abnormal tear ducts — sometimes congenital, sometimes caused by inflammation or a foreign object
- Eye infections or allergies — both can increase tear production directly; a dog with watery eyes, itchy skin and ear trouble together is probably allergic, and our guide to itchy skin in dogs covers that side
- Ingrown eyelashes or hair irritating the eye — common in breeds with hair growing close to the eyes
- Teething in puppies — many puppies stain more between about 4 and 7 months and improve once adult teeth are through
If staining appears suddenly in a dog that's never had it before, or is paired with redness, discharge, squinting, or your dog pawing at their eyes, it's worth a vet check rather than assuming it's ordinary porphyrin staining (Animal Friends).
How to Remove Tear Stains Safely
Existing stain is dyed fur — it grows out rather than washes out — so removal is really about lifting what you can and stopping new pigment building up while clean fur grows through.
- Warm water and a soft cloth or cotton pad, twice a day, wiped away from the eye. This does most of the work.
- Dog-safe tear stain wipes or a saline eye wash for stubborn crust — saline is the same thing vets use and can't hurt the eye
- A fine-toothed flea comb to lift dried crust out of the fur without pulling
- Have the groomer trim the fur short under the eyes so stain has less to cling to and new growth comes through clean
What not to use: hydrogen peroxide, bleach, apple cider vinegar, or human make-up remover anywhere near the eye — all can burn the cornea. Be careful with tear-stain powders and "eye whitening" products too: some rely on drying agents that irritate, and the old-style oral tear-stain supplements contained tylosin, an antibiotic — that's why they've been removed from sale in several countries, and giving a dog a daily antibiotic for a cosmetic issue isn't something any UK vet would support.
Preventing Tear Staining Day to Day
Daily Facial Hygiene
Gently wiping the area under the eyes daily with a damp cloth or dog-safe eye wipe helps prevent porphyrin from sitting on the fur long enough to oxidise and darken. Dry the fur afterwards — damp fur is where yeast starts.
Keep the Fur Trimmed
Short hair around the eyes helps tears drain properly rather than pooling against the skin, and reduces the amount of fur available for staining to show on.
Use Stainless Steel or Ceramic Bowls
Plastic bowls scratch and harbour bacteria that can irritate the face and chin; a simple swap many groomers recommend.
Consider Water Quality
Some owners find switching from tap water (which can be high in minerals) to filtered water helps reduce staining in sensitive dogs, though the evidence here is more anecdotal than proven.
Be Cautious With Over-the-Counter Supplements
Some products marketed for tear staining work by binding porphyrins, but not all are equally safe or effective, and it's genuinely worth checking with your vet before using them, particularly for long-term use (Animal Friends).
When to See a Vet
Book a vet visit if tear staining appears suddenly, worsens quickly, or comes with redness, discharge, odour, squinting, or signs your dog is uncomfortable. These can indicate an infection, blocked duct, or other issue that needs proper diagnosis rather than home management.
FAQ
What causes tear staining in dogs?
Tear staining is caused by porphyrin, an iron-containing pigment in tears that oxidises and turns reddish-brown on contact with air. It's usually related to facial structure causing tears to spill onto the face rather than a sign of illness.
How do I get rid of my dog's tear stains?
Wipe under the eyes with warm water twice a day, use a saline wash or dog-safe wipes for crust, comb out dried stain, and keep the fur trimmed short — the stain grows out as clean fur comes through. Never use peroxide, bleach or vinegar near the eyes.
Is tear staining linked to gut health?
A 2026 study found a genuine correlation between gut bacteria and porphyrin metabolism in dogs prone to tear staining, though this doesn't mean any specific probiotic product is proven to reduce staining on its own.
Which dog breeds get tear stains the most?
Brachycephalic breeds like Bulldogs and Pugs, small and toy breeds like Bichon Frise and Shih Tzu, and white or pale-coated dogs are most commonly affected.
Are tear stain removers safe?
Water-based wipes and saline are safe. Avoid products with drying agents or bleaching claims, and avoid the older oral tear-stain supplements that contain tylosin, an antibiotic, which UK vets don't support for routine use.
When should I worry about tear staining?
See a vet if staining appears suddenly, worsens quickly, or is accompanied by redness, discharge, odour, or signs of discomfort.
Are puppy tear stains normal?
Yes — puppy tear staining is very common, especially during teething between roughly 4 and 7 months, and usually settles as adult teeth come through and facial structure matures. The same gentle daily wiping used for adult dogs works well for puppies too.
This article is for general information only and isn't a substitute for veterinary advice. If your dog's tear staining changes suddenly or is paired with any sign of discomfort, contact your vet.
