Tear Stains, What Porphyrin and Blocked Tear Ducts Have to Do With It
Tear stains are that reddish-brown discolouration you often see running from the inner corner of a dog's eyes down the muzzle, most noticeable on white or light-coloured breeds like Maltese, Poodles, and Bichons, though any dog can get them.
What's actually causing the staining
The colour comes from porphyrins, iron-containing compounds naturally present in tears, saliva, and other bodily fluids. When tears overflow onto the fur instead of draining normally through the tear ducts, the porphyrins oxidise on contact with air and light, turning the fur that reddish-brown colour over time. It's a chemical reaction, not dirt, which is part of why plain wiping alone doesn't fully solve it.
Common Underlying Causes, Flat-Faced Breeds, Allergies, and Eye Irritation
Several things can lead to excess tearing or overflow:
- Breed anatomy, flat-faced breeds and those with shallow eye sockets often have tear ducts that don't drain efficiently
- Blocked or narrow tear ducts, sometimes present from birth
- Ingrown eyelashes or eyelid abnormalities causing irritation
- Allergies, whether environmental or food-related
- Eye irritation from dust, hair falling into the eyes, or shampoo residue
- Teething, in puppies, which can temporarily increase tearing
Day-to-Day Management with a Tear Stain Wipe and Eye Hygiene
Gently wipe the area under the eyes daily with a soft, damp cloth or a tear-stain wipe made for dogs, working from the inner corner outward. Keeping the hair around the eyes trimmed short (or asking your groomer to) stops fur from constantly sitting in tear-soaked, staining contact with the skin. Some owners find switching to a filtered water source or a different food helps if allergies are a factor, though this is worth discussing with your vet rather than trial-and-error with a sensitive dog.
What to be cautious about
Be wary of "tear stain remover" products that rely on antibiotics or dyes to mask discolouration rather than address the cause, some have raised safety concerns over the years. A simple, vet-approved wipe and good hygiene is the safer starting point for most dogs.
Diet's role, realistically
Some owners report improvement after switching food, particularly if allergies are contributing to excess tearing, but results vary a lot between individual dogs and it's not a guaranteed fix. If you do try a diet change for this reason, give it several weeks and ideally do it under your vet's guidance so you can rule other causes in or out at the same time.
When it's more than cosmetic
Occasional light staining is common and often just anatomy. But get your vet to take a look if you notice thick or coloured discharge (rather than clear tears), redness or swelling around the eye, your dog pawing at or squinting one eye, or a sudden increase in tearing, these can point to an infection, a foreign body in the eye, or a genuinely blocked duct that may need treatment.