Tear Stains
Tear staining is usually caused by excessive tear production. (Epiphora) “While tear staining is typically no more than a minor annoyance, it can also be a symptom of a serious eye health problem.” [1]
Medical causes of tear staining can include: [1]
Ingrown eyelashes
Infection of the eye
Unusually large tear glands
Unusually small tear duct openings
Glaucoma or another eye disease
Entropion (inverted eyelid)
Ear infection
Medications
Exposure to secondhand smoke
Poor-quality diet
Plastic food bowls
Stress
Teething in puppies
Tearstains are typically the result of porphyrins. Porphyrins are naturally occurring molecules containing iron.
When tears and saliva containing porphyrins sit on light-colored fur for any period of time, staining will occur. The iron-containing stains darken when exposed to sunlight. [1]
“Now, if the stains are more of a brown color than rust colored, it's likely your pet has developed a yeast infection on her face because the fur under her eyes is constantly wet with tears.” Brown stains from a yeast infection are different from red staining caused by porphyrins. “Pets can also have both a porphyrin stained face and a secondary yeast infection from the constantly moist skin.” [1]
“the telltale reddish-brown stains on its mouth, ears, feet, and around the eyes that indicate the growth of a very specific species of yeast, Malassezia spp.” [2] “Malassezia is a bad yeast, at least when there is too much of it. True, it’s part of the normal flora – the organisms that normally inhabit the skin. Normally the body’s immune system keeps its growth in check. But when it grows out of control, it creates an imbalance in the body’s homeostasis – the healthy balance of your dog’s biological systems (1). The good news is that Malassezia overgrowth can be corrected.” [2]
“While there are no peer-reviewed data on the effect of diet on tear staining, my clinical experience suggests that non-allergic dogs that have tear staining can benefit from a change to a fresh diet.” [2]
“Warning! Avoid products that claim to clear up tear stains using an additive to your dog’s food or water. Most of these contain antibiotics, which are ineffective against yeast, and can significantly upset your dog’s natural microflora.” [2]