What Is The Nasolacrimal Duct In Horses?

The "nasolacrimal duct" is a tear duct that drains through an opening in a horse's nose.

In horses of typical anatomy the nasolacrimal duct drains tears from the corner of the horse's eye, down the tube-like nasolacrimal duct, and out through an opening at the bottom of the nose.

Though small and sometimes difficult to see, this opening is often visible to the naked eye inside the horse's nostril.

Below: The yellow arrow is pointing to the nasolacrimal duct inside the left nostril of a horse.

Problems With The Nasolacrimal Duct

If a horse's eye tears excessively the problem may be a nasolacrimal duct that is blocked by debris, inflammation, or scar tissue, or that has been damaged. Less commonly, a horse may have a congenital condition in which there is not an opening for the nasolacrimal duct in the nostril.

These conditions usually result in excessive tearing or matter in the eye since there is nowhere for the fluid to drain. Fortunately, these conditions are often easily treatable.

Below is a photo of a young mare who was born without an opening in her nostrils for her nasolacrimal ducts (this condition was present on both sides of her face).

Surgery was performed to create openings, then a small tube was inserted the entire length of her nasolacrimal ducts to hold the new openings open until they healed. Excess tubing was brought out the top (at the eyes) and bottom (at the nose) of the nasolacrimal ducts then stitched to her face to keep it in place. When the surgically created openings were healed, the tubing was removed.

Below: A mare after surgery on her nasolacrimal ducts. She made a full recovery.