Caring for a One-Eyed Horse

Updated August 13, 2024 | By: Shannon J. Murray, DVM, MS, DACVS-LA

The sight of a horse with only one eye looking back at you might be a bit concerning at first. However, the truth is, one-eyed horses often enjoy a great quality of life and can be quite successful in their athletic careers.

Whether you’re thinking of adopting or buying a one-eyed horse or considering surgery to remove an eye from your own horse, we’ll help you understand what having a single eye means for a horse (and for you).

What is Enucleation?

Enucleation is the term used for the surgical removal of an eye and its associated structures. This is a routine surgery that a veterinarian performs on a horse that is anesthetized and laying down or standing while sedated.

Performing an enucleation on a standing horse minimizes the risks and costs associated with general anesthesia. However, not every patient is suitable for a standing enucleation. Horses with behavioral issues or those that do not sedate well are poor candidates for a standing enucleation [1].

Reasons for Removing a Horse’s Eye

Enucleation is commonly performed when the eye is no longer responding to medical treatment, vision can no longer be maintained, and/or when the eye is a continued source of pain for a horse. Enucleation may also be an option following a traumatic injury to the eye where medical management is not an option.

Common conditions and events that may result in removing an eye include:

• Trauma to the eye itself or the surrounding structures (such as a severe, non-healing corneal ulcer)
• Infection
• Neoplasia (abnormal mass of tissue)
• Equine Recurrent Uveitis (ERU or moon blindness)
• Keratitis (inflammation or irritation of the cornea)
• Glaucoma
• A painful, blind eye

In what cases would a non-functioning eye not be removed?

If a non-functioning eye is not causing your horse discomfort, then it may not need to be removed. Enucleation is most often elected as the humane choice for horses with a painful eye.

Benefits of removing a painful eye

By removing the eye, the source of ongoing discomfort for your horse is eliminated. Depending on your veterinarian’s prognosis for the eye, enucleation may not only relieve pain sooner, but it may also be more cost effective than long-term medical treatment.

This is a conversation for you to have with your veterinarian to determine what is best for you and your horse, taking into consideration the various circumstances around the eye injury or disease.

Recovery Following Enucleation

If enucleation is elected as the best option for your horse, there will be a period of recovery following surgery. During this recovery period, turn-out and exercise will be determined by your veterinarian.

Post-operative care often includes:

• Medications (antibiotics and nonsteroidal anti-inflammatory)
• Often, protective eyewear is recommended to prevent trauma to the surgical site.
  • Eye protective masks and goggles, such as the EquiVizor Recovery Vizor and the Restoration Equine Mask, help shield the eyes from insects, dirt, and debris while the area heals.

If non- absorbable sutures are placed, a recheck appointment with your veterinarian for suture removal will take place 10 to 14 days following surgery. It is common for post-op swelling to occur. Frequently, the surgical site will give the impression that a globe remains under the incision. However, unless an orbital implant was placed during the enucleation, over time, the eye socket will have a sunken appearance.

As your horse adjusts to their new one-sided vision, try using your voice when working around them. By talking to your horse before approaching their blind side, you’ll lessen the chances of spooking them. Many horses adjust quickly immediately after surgery by leading back to their stall well and not having difficulty with managing space in their stall (walls, hanging buckets, etc.).

Supplements That May Support Eye Health & Normal Inflammatory Response

Specific ingredients in antioxidant and immune system supplements may be helpful in promoting overall ocular health and function of your horse’s retained eye, especially if they’re suffering from a chronic condition such as ERU. Speak with your veterinarian about whether these ingredients may complement your horse’s treatment plan by supporting recovery.

• Lutein, astaxanthin, and zeaxanthin are antioxidants that work within the eye’s retina cells to help protect against oxidative damage from UV rays.
• Quercetin and luteolin are flavonoids that provide antioxidant effects and may be helpful if your horse’s eyes are irritated by allergic reactions. Vitamin A is critical for vision and supports the function of the protective outer layer of the eye (cornea).
• Essential vitamins and minerals, like vitamins C, E, zinc, and selenium, are vital for proper immune system function and can help protect cells from the damaging effects of oxidative stress. Many vitamins and minerals support the growth and activity of immune cells during times of stress (such as an injury).
• Omega-3 fatty acids have anti-inflammatory properties that can assist in modulating immune responses. A balanced ratio of omega 3 to omega 6 fatty acids promotes a normal response to inflammation in the body and aids in the absorption of fat-soluble vitamins A, D, E, and K.
• Other ingredients that may support a normal inflammatory response include turmeric, MSM, and devil's claw.

Looking Forward with Your One-eyed Horse

The vast majority of horses adapt well to having only one eye. They may even go on to compete at the highest levels like Viscera, a Hanoverian mare ridden by Swedish eventer Therese Viklund, who competed at the Tokyo 2020 Olympic Games after having her left eye removed as a result of uveitis.

A long-term follow-up study for horses having undergone enucleation showed that about 91% of owners were satisfied with the outcome of the enucleation. In addition, about 22% of the owners wished that they had moved forward with the surgery sooner. This study also noted that following enucleation, about 77% of the one-eyed horses were able to perform at an equal or higher level than prior to surgery [2].

In another study, roughly 85% of horses returned to their pre-surgical discipline (including racing and jumping at high levels). However, rules do exist within different disciplines regarding whether one-eyed horses may be allowed to perform [3].

How does the blind side affect the horse?

One thing to note is that research has shown horses appear to show some laterality, meaning they may be a bit more reactive to new stimuli presented on one side versus the other. For horses, this is typically their left side.

There is not enough evidence to draw conclusions, however, there seems to be a trend showing that horses undergoing a right-sided enucleation are more likely to be retired from their athletic careers earlier. A specific study showed that most horses that did not return to their previous level of performance had right blind sides (some just due to anticipated changes in performance versus actual changes) [3].

An Eye Emergency is a True Emergency

Many problems involving eyes are true equine emergencies and horses experiencing these should be seen by a veterinarian or veterinary ophthalmologist immediately. A horse’s long-term prognosis for vision and saving the eye often depends on immediate, accurate diagnosis and treatment.

Some signs that indicate you should call your vet include:

• Tearing or Discharge
• Swollen eye lids
• Holding the eye closed
• Squinting
• Cloudy eye, etc.

If you are ever confronted with news that the best treatment for your horse ends up being enucleation, know that your one-eyed horse can continue to live a full, happy life with a good prognosis for returning to their previous level of work and up the levels.

Evidence-Based References

1. Pollock, Patrick J et al. “Transpalpebral eye enucleation in 40 standing horses.” Veterinary surgery : VS vol. 37,3 (2008): 306-9. doi:10.1111/j.1532-950X.2008.00382.x
2. Wright, K. et al. “A multicenter study of long-term follow-up and owner satisfaction following enucleation.” Equine Veterinary Journal 2018; 50:186-191.
3. Utter, M.E. et al. “Return to work following unilateral enucleation in 34 horses (2000-2008).” Equine Veterinary Journal 2010; 42 (2) 156-160.