Excessive tear production, known medically as epiphora, is a fairly common problem in pets. Skin irritation, infection and odor can occur over time with chronic exposure to excessive tears that drain down the pet's face.

Excessive tearing can be caused by either irritation to the eye or abnormal tear drainage. Any irritant in the eye may produce more tears. Further, chronically irritated eyes, which can be difficult to manage, can result from viral conjunctivitis, glaucoma, or eyelash abnormalities. In cats, viral conjunctivitis is one of the most common causes of excessive tearing. Excessive tearing from conjunctivitis can result from infection, trauma, allergy, or irritants like dust and smog, all of which can often be treated medically. In addition, hair growing into the eyes or eyelashes that grow at abnormal angles can result in irritation.

Excessive tearing due to abnormal tear drainage may result from abnormal drainage ducts of the eyes and from eyelids that are turned inward, known as entropian. Also, some breeds, such as Poodles and Bichon Frises, can have an eye socket that is too shallow to contain the tears. Vigorous flushing of saline through the ducts or surgery may be able to treat problems with the tear ducts.

Veterinary attention should be sought if excessive tearing is accompanied by squinting or pawing at the eye, if excessive tearing occurs suddenly, or if any loss of vision occurs.