For the new study, researchers administered oxytocin to the dogs’ lacrimal gland, which is responsible for tear secretion.

Next are two sets of lacrimal glands that supply the watery tears.

Tear glands, also called lacrimal glands, are a particular challenge to study, says Darlene Dartt, who studies tear production at Massachusetts Eye and Ear in Boston.

He has a rare type, “a mucoepidermoid carcinoma of the lacrimal gland,” which threatens his eyesight and his life.

This chronic and usually progressive syndrome attacks secretory tissues throughout the body, primarily, but not exclusively, the salivary and lacrimal glands of the mouth and eyes, the respective sources of saliva and tears.