My horses’ eye is tearing, is this an emergency?
Tearing is the first sign of a possible corneal ulcer which requires immediate treatment. Delaying treatment of an eye ulcer in horses can create a ‘complicated ulcer’ which may take months to heal. Most uncomplicated corneal ulcers will heal in 3-5 days if caught early. Tearing in both eyes can indicate environmental allergies, but a corneal ulcer cannot be ruled out until the eye is stained with a fluorescein dye to determine the appropriate treatment.
What are other causes of excessive tearing in horses?
First your horses corneal should be evaluated for any abrasions or ulcerations as this is the number one cause of tearing in horses. If both eyes are tearing, environmental allergies would be high on the list as a cause of tearing. The ‘tears’ should drain at the middle corner of the eye into a duct called the nasolacrimal duct. The nasolacrimal duct travels in bone that drains at the nose called the nasolacrimal duct orifice. If this duct is compromised, usually from previous trauma, the tears will not be able to drain at the nose which causes tearing down the face. Typically this will occur on one side only, but trauma can occur on both sides causing tearing this way. Other causes of tearing in horses include eyelid disorders (entropion) eyelash disorders leading to ulcers (trichiasis, distichiasis), foreign bodies, third eyelid neoplasia, and more.
My horses eye is swollen, should I give him some dex (dexamethasone)?
No. In horses you should NEVER administer dexamethasone for an eye injury or eye swelling without staining for a corneal ulcer first. Dexamethasone is a steroid which prevents healing, causes enzymatic tissue degradation, and increases the risk of infection of the cornea.
Do all eyelid lacerations need to be repaired immediately?
It is ideal to suture lacerations within the first 12-24 hours to have the best possible outcome. The longer a laceration goes without repair, the longer the exposed site may become infected, which may cause sutures to fail.
Why is it important to suture eyelid lacerations instead of letting them heal on their own?
The eyelids of a horse have many important roles. They help distribute tear film across the cornea allowing the eye to stay hydrated. This helps to prevent ‘exposure keratitis’ which refers to an ulcer that forms if tears cannot be distributed properly across the cornea. For example, if the eyelid margin is lacerated and heals on its own, it may decrease the overall size of the eyelid margin. In return, this creates an open space in between the eyelids when they are closed that prevents the middle of the cornea from being lubricated, creating an ulcer over time.
Another important job of the eyelid is to secrete lipids which prevents the water component of tear film from evaporating. These lipids are secreted from the meibomian gland found in the upper eyelid. If this portion of the eyelid is lacerated, it is crucial to repair to preserve proper eyelid tear function.