Have you ever wondered why/how we (humans) cry? At least one answer to the "why" has been obvious of late. Excess tear production happens in response to smoky particulants in the air. Other animals share that reason to tear up, but humans are the only known species that also cry in response to the release of specific hormones triggered by the limbic (emotional) system of the body. Despite our penchant to anthropomorphize everything our animals do, if your horse has tears running down her face you should look for a cause related directly to the eyeball and it's associated structures. This summer's heat and excessive dryness, plus polluted air has had an impact on sensitive eyes. We are seeing lots of ocular discomfort which sometimes can lead to more serious eye problems.
Did you know that the horse has one of the largest eye balls of any land mammal? Because of the location of the their eyes towards the sides of the head, the horse can see almost 360 degrees around itself. Given the prominence of the eyes and the nature of the beast, the equine eye is also prone to injury. One of the first signs of an eye problem may be excess fluid or tearing. The nasolacrimal duct system is designed to manage a constant flow of tears which serves to clear debris, provide oxygen & nutrients and to lubricate the cornea of the eye. The tear film is constantly secreted with the overflow collected in the lacrimal sac, drained via the ocular puncta, into the lacrimal canal and out the nose at the nasal puncta. (Humans have the same system which is why, when you cry hard, you also get the sniffles.)
If tears are running down your horse's face, either too much fluid is being created or the nasolacrimal drainage system has gone awry. Too much tearing can be caused by any kind of ocular discomfort. The first thing to notice is whether or not there are any other signs of eye irritation. Is the animal squinting, is the eye red or the area around it swollen. Eye injuries from trauma or infection can be justifiable emergencies, requiring prompt treatment to avoid catastrophe. If the eye itself looks comfortable, that's good news because it's more likely that the problem is with the nasolacrimal drainage system rather than the eyeball itself.
There are several possibilities to consider if your cry baby horse has a problem with his nasolacrimal system. Sometimes a horse is born without a nasal puncta, a condition called congenital puncta atresia. It is remedied by placing a stent to recreate the exit hole (nasal puncta). Functional obstruction of the canal or either puncta can occur from a primary obstruction within the system from debris or a foreign object. It can also occur secondarily, due to swelling after trauma to the face or with a sinus infection or a dental problem. Effective tear drainage can also be impeded in an animal with small eyes or one in very poor condition, where the eyeball actually sinks deeper into the socket, disrupting effective tear flow. While a "crying" horse is not always a health care disaster, it is a good idea to take steps to minimize the weeping in order to avoid secondary consequences, like an ulcer caused by rubbing or increased fly irritation causing conjunctivitis.
WHAT YOU CAN DO. A well fitting fly mask is helpful to screen out larger airborne particles and to decrease secondary fly irritation. Gently wash the face on a regular basis, use warm water to soften any crustiness from dried tears. You can help flush away irritants on the cornea with eye drops. Just like your own eyes, temporary allergy induced itching or particulate irritation is soothed by flooding the eye with a simple physiologic saline solution. It's best to use a non-medicated saline eye wash with no other chemical additives, unless the doctor says otherwise. If you're unsure whether or not there is more of a problem than mild irritation causing the tear overflow, it's best to call us for a more thorough ocular exam. A persistent tear duct obstruction can often be relieved by flushing the nasolacrimal system with a cannula inserted in either the ocular or nasal puncta. If the cornea is indeed the "window to the soul" it's a good thing to keep it bright and clear.