What causes tear stains in dogs?
The answer to what causes tear stains in dogs is usually an excessive amount of tears on the face, either from too many tears being produced or the tears not draining away properly. This could be the symptom of a serious medical condition or indicate an infection, so it is important to see your vet if you notice signs of tear stains for the first time.
Possible medical causes
Glaucoma – a serious condition that causes a build-up of pressure in the eye and can damage the optic nerve.
Eye infection – infections by bacteria, viruses or parasites can cause a discharge from the eye.
Conjunctivitis – inflammation in the eye’s lining can cause mucus, pus or discharge.
Ear infection – may cause the eye on the same side of the head to tear more than is usual.
Ingrown eyelashes – these can rub against the surface of the eye, causing irritation and damage.
Entropion – a condition where the eyelid rolls in, causing the eyelashes to rub against the eye and causing irritation.
Mechanical causes, due to the dog’s body construction
Large tear glands – larger glands produce larger volumes of tears.
Small tear duct openings – each eye has a tube running from the eye into the nasal cavity to drain the excess tears via the nose. Small openings to these ducts reduce their effectiveness and the excess spills over into the hair.
Blocked tear ducts – as for small duct openings, blocked ducts cannot remove the excess liquid from the eye. Some breeds of dog such as Poodles and Cocker Spaniels have a tendency for the drainage holes not to develop properly.
Scarring – if there has been previous infection or eye damage, tear drainage may reduce.
Hair around the eyes – if hair keeps getting into the eyes, it can wick the tears away, drawing the moisture from the eye and down to the skin.
Shallow eye sockets – particularly in brachycephalic dogs (breeds with short muzzles such as Pugs, French Bulldogs or Pekingese), eyes can bulge and protrude, sometimes so much that the eyelids never close completely, even when sleeping.
Other possible causes:
Irritant exposure – irritants like dust or smoke can cause the eye to water attempting to remove the irritating substance.
Allergies – allergic reactions can cause the eye to water excessively. These allergies can be seasonal, something in the environment or a reaction to the dog’s food.
Poor diet and stress – Anxiety and stress can cause a number of issues. A poor-quality diet filled with unsuitable or indigestible ingredients places stress on the dog’s body. Cheap, low-quality foods can often be a problem.
Teething – when puppies are teething, they produce more tears and tear stains may become apparent. It is a good idea to have your vet check that there are no other issues causing the tears but, once they have finished teething, the problem often goes away.