Eyes

Content

Intro

1. The eyes as a reflection of whole-body health
2. Everyday eye irritation & conjunctivitis
3. Pink-eye - what's actually happening?
4. Uveitis (ERU)
5. Why ERU is so challenging
6. Diagnosis
7. Signs
8. Supporting
9. Practical management and owners' tips
10. A final word

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 ability is intimately linked to their behaviour as a flight animal. They rely on their eyesight for safety, orientation, and confidence. Horses don’t wink, so if you notice one eye partially or fully closed, squinting, or avoiding light, it’s a sign that something isn’t quite right and needs attention.

The eyes as a reflection of whole-body health

Traditional Chinese Medicine (TCM) has long described the eyes as a reflection of the body’s internal state. Each part of the eye is associated with a different organ system:

• the iris with the liver
• the corners of the eyes with the heart
• the eyelids with the spleen
• the conjunctiva with the lungs
• the pupil with the kidneys

From both an Eastern and Western herbal perspective, immunity plays a central role in eye health, and the liver in particular is considered key. TCM describes the liver as “opening into the eyes”, and we often find that long-standing or recurring eye issues are linked with liver stress, blood deficiency, or wider immune imbalance.

In practical terms, when we support liver and immune health, eye resilience often improves alongside it.

Everyday eye irritation & conjunctivitis

Eye injuries, irritation and infections are fairly common in horses, but they should never be ignored. The equine eye is delicate, and problems can worsen quickly if left untreated.

A common early sign is excessive eye watering (lacrimation). At first, the eye may simply water more than usual, but if secondary infection develops, discharge can become thick, yellow, or pus-like.

Our Cookie was prone to sticky eyes in winter and during high pollen counts, and I know from experience that it's all too easy to become accustomed to seeing a slight discharge, particularly associated with flies in summer or miserable winter weather.

Our Pops also really suffered with an inherent 'pink eye' syndrome - her eyes watered constantly, turning yellow and crusty. She made it very clear that she didn't like me wiping it (understandable), and despite my best efforts with a face mask, she simply rubbed her eyes on her knees through the mask, creating more of a bacterial risk on the inside of the mask. Once we introduced EyeTonic, we saw improvement within a very short space of time, and we never looked back.

Pink eye – what’s actually going on?

Pink eye (conjunctivitis) in horses isn’t so different from pink eye in humans. The conjunctiva is the sensitive pink lining that covers the sclera and lines the eyelids, its role being to protect the eye from microbes while lubricating it with tears and mucus. Conjunctivitis occurs when this lining becomes irritated and inflamed.

Common triggers include:

• dust, wind, pollens
• flies and rubbing
• allergens
• viral or bacterial exposure
• blocked tear ducts

In many cases, pink eye is allergy-driven or viral, which explains why it often responds poorly to antibiotics. While conjunctivitis isn’t airborne, it is contagious, so keep an eye out for:

• excessive tearing
• redness around the eye rims
• discharge
• head shaking or knee rubbing
• sensitivity to light or dust

If you need to check the eye more closely, use your thumb and forefinger to gently part the eyelids. A horse won’t love it, but it’s better to look than ignore a potential problem.

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 either calendula, or chamomile, or both, both lovely supporting herbs with antibacterial, antimicrobial and anti-inflammatory properties. Let it cool and use as a gentle eyewash with a cotton wool pad.

Uveitis (ERU)

Equine Recurrent Uveitis (ERU) is recurrent inflammation of the uveal tract of the eye and remains one of the leading causes of blindness in horses. It’s painful, unpredictable, and becoming increasingly common.

You may also hear it referred to as:

• Periodic Ophthalmia
• Recurrent Iridocyclitis
• Moon Blindness (historically linked to lunar cycles)

ERU does not discriminate - it can affect any horse, of any breed, age or lifestyle.

Why ERU is so challenging

ERU is an immune-mediated disease - in simple terms, the body’s immune system becomes confused and begins attacking the eye itself.

Once ERU begins, it often becomes a pattern of repeat flare-ups. Each episode can cause cumulative damage, increasing the risk of permanent vision loss. Early recognition and consistent management are absolutely critical.

While the exact cause remains elusive, contributing factors include:

• leptospirosis (the most commonly implicated infectious trigger)
• parasitic migration (notably Onchocerca cervicalis)
• trauma
• immune dysregulation
• antigen mimicry and autoimmunity

One of the frustrations is that ERU may not appear until months or even years after the initial trigger, making prevention difficult.

Diagnosis

If you know what your horse’s eyes normally look like, you’ll notice changes quickly. Redness, swelling, cloudiness, squinting, or light sensitivity should never be dismissed.

If you suspect ERU but don’t see obvious changes, take your horse into a dark stable and observe the pupils. A pupil that fails to dilate in the dark can indicate painful spasm and requires immediate veterinary attention.

The earlier ERU is identified, the greater the chance of preserving vision.

Signs of ERU

Common signs include:

• watery or swollen eyes
• squinting
• visible blood vessels
• cloudiness or colour change
• extreme light sensitivity
• constricted pupil in darkness

Additional signs may include head shaking, nasal discharge, rubbing, loss of balance, or behavioural changes linked to pain or reduced vision. Equally, ERU is very painful, and pain alone can make a horse unpredictable. If pain is suspected, veterinary support is essential.

Supporting ERU

Conventional management may include atropine, steroids, antibiotics (if ulceration is present), and systemic anti-inflammatories. In severe cases, eye removal may ultimately be the kindest option.

Alongside acute veterinary care, many owners explore complementary approaches including herbs, nutritional support, acupuncture, MSM, and immune support. The long-term aim is always the same: reduce inflammation, stabilise immunity, and minimise triggers.

Anything that promotes inflammation can trigger an ERU episode – stress, dietary changes, weather, parasites, medications, and immune challenges all play a role. Strengthening the immune system and reducing inflammatory load may help reduce the frequency and severity of flare-ups.

Practical management & owner tips

Living with ERU (or partial blindness) requires awareness, patience, and consistency.

• Protective face masks help shield the eye from light, wind and debris. Keeping a daily log of weather, turnout, stressors, medications and flare-ups can reveal patterns over time.
• If vision is compromised, begin handling from both sides, talk to your horse constantly, and maintain physical contact so they know where you are. Horses adapt remarkably well when they feel safe and supported.
• Turnout choices matter. Some blind horses thrive in a calm group that instinctively protects them; others need quieter, individual spaces. Let your horse tell you what works.
• Training and riding can often continue with thoughtful adjustments, clear voice cues, and trust. Consistency is key - neither over-babying nor demanding too much.

Accidents may happen, but horses are forgiving, and we learn as we go.

A final word

Eye problems are never just “about the eye”. They’re often the body signalling a deeper imbalance involving immunity, liver health, stress, or environment.

With awareness, early intervention, and thoughtful support, many horses can remain comfortable, confident, and happy — even when vision is compromised.