Vesna had noticed a minor problem with Chira: she had two brown streaks on her face, running down from the inner corner of each eye. It made her look as if she had mascara leaking down her face. When Chira came to see me for a routine vaccination, Vesna asked about the brown streaks: what were they?
The answer is simple: the brown colour is caused by tears overflowing from Chira’s eyes, spilling down both sides of her muzzle. The tears contain chemicals that react with bacteria and oxygen in the atmosphere, turning dark brown. It’s like a biological equivalent of rusting metal. Tear stains like this are unusual in Labradors; they are far more common in small, white breeds of dog like Poodles and Bichons. They are probably common in dark furred dogs too, but because the brown marks aren’t visible against a background of brown or black fur, owners rarely notice them.
Why do tear stains happen?
Since the problem is due to overflow of tears, the first thing to look at is the tear drainage system. In all dogs, tears are produced continually, to keep the eyeball moist and comfortable. Normally, the tears drain out of the eye via a duct system: there’s a tiny hole on the inner aspect of the corner of each eye. This opens into a narrow tube that carries the tears through the skull to an exit hole in the inside of each nostril. There’s a constant flow of tears from the corner of the eye, down this tube inside the skull, to the tip of the nose.
This is the reason why healthy dogs are well-known for having cold, wet noses: if a dog is sick or dehydrated, the tear flow is reduced, and the dog then has a warmer, drier nose. In some dogs, the tear ducts become blocked: when this happens, the effect is just like a blocked drain overflowing. Instead of dripping down the tear ducts to the nose, the tears spill down the face, leaving those brown stains.
Blocked tear ducts are the most common cause of tear stains, especially in smaller, short nosed dogs. It’s easy to check if the tear ducts are blocked: a green dye is put into each eye, allowing the tracks of the tears to be followed. In a normal dog, the dye moves down the tear ducts, causing the tip of the nose to turn bright green within a few minutes. If the tear ducts are blocked, the green dye spills out of the eyes, following the same tracks as the brown tear stains. Blocked tear ducts can often be physically unblocked by flushing them out, and this can solve the problem.
In Chira’s case, the tear ducts were not blocked: you can see the green colour at her nostrils in the photos, demonstrating that she has normal tear drainage. Her problem is different: she has an overflow of normal tears. This is more difficult to cure: it’s to do with a dog’s anatomy, with her tear ducts just not draining her tears properly. It’s like a pipe that’s too narrow to drain gutters, causing on overflow of water.
It’s difficult to cure this type of tear spillage, but it’s only a cosmetic problem: Chira isn’t aware that she has mascara-like streaks on her muzzle. The stains can be minimised by regular cleaning of the area with mildly salty water, and applying a smudge of Vaseline to the fur to stop it from becoming damp. Vesna isn’t at all worried about the brown stains: she is just relieved that there isn’t a serious problem affecting Chira’s health.
Tips
- Brown tear stains are common in dogs with light coloured fur
- Small white dogs are most commonly affected
- Vets can help to identify the cause, and give treatment when need
Please note that I am unable to answer veterinary questions in comments. If you have questions or concerns about your pet's health it is always better to contact your vet.