Principal Body System: Control
Definition: Sense organ comprising eyeball, optic nerve, brain and accessory structures, i.e. eyelids (including third eyelid, nictitating membrane) and lacrimal apparatus
Function: Regulates body activities through nerve impulses via visual pathway
The equine eye is the largest of any land mammal, and a beautiful thing to behold. Clear and bright, the lids tight, and the inside of the lid pale pink and moist.
A horse's visual abilities are directly related to the horse's behaviour and the fact that the horse is a flight animal. They never wink, so if your horse has one eye partially or completely closed, it could mean that something may be wrong.
In Traditional Chinese Medicine (TCM), the eyes are described as the window to the inner workings of the body, with the eyes thought to be connected to all of the internal organs. Each part of the eye is associated with a particular element and corresponding Yang organ - the iris is represented by the liver; the heart relates to the corners of the eyes; the upper and lower eyelids correspond to the spleen, the conjunctiva the lungs, and the pupil the kidneys. For healthy eyes, a healthy immunity is key.
However, although all the organs have their own connection to the health of the eyes, TCM considers that the liver is the key organ connected to proper eye function. The liver opens into the eyes, and chronic eye problems can usually be traced to a deficiency of liver Yin or blood, for example. It is thought in TCM that it is common to resolve eye disorders successfully by treating the liver.
Eye injuries and infections are fairly common in horses, but if ignored they can worsen quickly. If the eye becomes badly infected, the structures of the eye can be eroded until the entire eye collapses.
A typical sign that something is wrong is profuse tear production (lacrimation). At first, the eye may just water more than normal, but if secondary bacterial infection develops, there will be pus in the discharge. Our Cookie is prone to sticky eyes in winter and during high pollen counts, and I know from experience that it's all too easy to be accustomed to seeing a slight discharge, particularly associated with flies in summer or miserable winter weather. However, this could also means that a more significant discharge might be ignored.
Our Pops also really suffers with an inherent 'pink eye' syndrome - I've never known a horse lachrymose so much, which in her turns yellow and crusty. She's made it very clear that she doesn't like me wiping it (understandable), and a face mask doesn't seem any good as she simply rubs her eyes on her knees through the mask, creating more of a bacterial risk. I eventually put her on our ERUTonic (now our EyeTonic) - literally 24hrs later her eyes were improving, and we've never looked back.
Pink eye in horses isn’t so different from pink eye in humans. The conjunctiva is the sensitive pink lining of the eyelids that covers the sclera, preventing microbes from entering the eye while lubricating the eye with mucus and tears. Pink eye, aka conjunctivitis, appears when the conjunctiva becomes irritated and inflamed - it literally means something's been rubbed into their eyes, usually from rubbing their eye on their knees due to wind, pollens, dust or flies - and causes irritation which then leads to infection. It can be caused by virusus or bacteria, an allergic reaction, or blocked tear ducts. Since the majority of cases are viral or allergy-related, pink eye doesn't seem to respond to antibiotics.
While conjunctivitis in horses is not airborne, it is contagious, so keep an eye out for overly weepy eyes, head shaking, knee scratching, discharge, redness around the eye rims, an aversion to bright lights or sensitivity to dust.
If you need to take a closer look to confirm redness and irritation, bear in mind that a horse won’t be thrilled about you poking around there, but you can use your thumb and forefinger from one hand to gently spread the eyelids apart to better see signs of concern.
That said, the most common cause of poor vision is exposure to cold and dampness, depriving the eyes of vital warmth and nourishment which results in poor circulation to the eyes. A fly mask can usually help, and you can clean the area very gently with a simple saline solution 3-4 times a day - this can be made up with 1-tsp salt to a cup of lukewarm water - it should taste like tears.
Another useful tool in the box is to make a tea of calendula and chamomile, both lovely healing herbs with antibacterial, antimicrobial and anti-inflammatory properties. Let it cool and use as a gentle eyewash or compress.
There's a wonderful selection of effective herbs for equine eye health, and with prompt management many eye problems can be brought under control within a few days.