Q: My dog seems to have a runny eye. It is making tear stains in his fur. What should I do?
A: Any problem with the eyes should be evaluated by a veterinarian. Excessive tearing can be caused by many different problems. Some are harmless, but some are more serious. Small tumors or foreign material under an eyelid can lead to excessive tearing. Glaucoma, eye infections, and disruptions of the cornea are more examples of potentially serious problems that can cause increased tear production.
It is also very common for dogs to have problems with the duct in the inner corner of the eye, called nasolacrimal ducts. These ducts usually drain tears from the eye into the nasal passages. If one or more becomes obstructed, the tears will spill over onto the face. A blocked nasolacrimal duct is diagnosed by placing a florescent stain into the eyes and using a black light to detect the stain in the nostrils. If the ducts are open, the stain will be visible as a bright glow in the dog’s nostril. If no stain drains into the nasal passages, the veterinarian will know the ducts are blocked.
A blocked nasolacrimal duct is not a serious medical condition. Usually excessive tearing is the only symptom. Occasionally a dog will develop persistent skin infections near the corner of the eye from the constant moisture. Other times the abnormal tear flow will lead to repeated bouts of conjunctivitis. If the blocked duct does cause a problem, an attempt can be made to reopen it.
To reopen a blocked duct, the dog in placed under very heavy sedation or general anesthesia. A small metal catheter is placed into the opening of the duct, either in the corner of the eye, through the nostril, or both. Sterile saline is used to flush the duct under pressure. If dirt, mucous, or other debris can be dislodged, then the duct may open up. If scar tissue has formed in the duct or the duct was never formed properly, the procedure may not work. If it does work, the dog is usually given eyedrops with a topical steroid and antibiotic for several days after the procedure.