While severe equine eye injuries or disorders can be gruesome in appearance, they generally aren't life-threatening. Thanks to medical and technological advances, veterinarians can now treat eye issues more effectively than they have in the past. But if treatment fails, veterinarians also have the option of removing the eye without the risks associated with general anesthesia using a procedure called a standing enucleation.
At the 2013 American Association of Equine Practitioners' Convention, held Dec. 7-11 in Nashville, Tenn., Wendy Townsend, DVM, MS, Dipl. ACVO, assistant professor of ophthalmology at the Purdue University College of Veterinary Medicine, reviewed how to perform a standing enucleation and what to expect.
Townsend said the standing eye removal surgery is a reasonable alternative to enucleations performed under general anesthesia, but case selection is critical to success—not every horse is a good candidate for this procedure. The standing procedure could benefit large, lame, or geriatric horses that could be at-risk for complications when recovering from general anesthesia, she said. Case selection should also take into account the horse's temperament (calmer is better), the degree of discomfort (less painful eyes are better), and the extent of surgery (procedures involving resection and reconstruction—such as eye removals related to neoplasia, or tumors—aren't good candidates for the standing procedure), she added.
Next, Townsend reviewed with veterinarians some key points to consider when removing an eye in a standing, sedated horse:
- Place the horse in stocks and use a head rest (which can be something as simple as a trash can under a foam anesthesia pad or hay bales covered in towels). Also, ensure the horse's halter is well-padded to prevent pressure points and potential nerve damage during sedation.
- Before beginning the procedure, administer the appropriate medications. Townsend said she administers flunixin meglumine (a non-steroidal anti-inflammatory drug), gentamicin (an antibiotic), and potassium penicillin (another antibiotic) prior to surgery, as well as a bolus of detomidine (a sedative) and butorphanol (a pain reliever). She added that the horse might need additional detomidine throughout surgery to remain adequately sedated.
- Next, veterinarians should administer the local anesthetics and nerve blocks prior to surgery. Townsend reviewed how and where to administer the injections with the veterinary audience.
- Finally, the veterinarian can perform the enucleation. Townsend stressed that practitioners should ensure the entire eye globe and associated structures are removed from the horse's skull before closing the incision and applying post-operative dressing.
After surgery, Townsend recommended maintaining the horse on flunixin meglumine for three to five days after surgery and antibiotics, as needed. The post-operative dressing will remain in place for a day after the procedure, and the sutures are removed 10-14 days after surgery.
Townsend noted that complications are rare, and she has not experienced any in her practice.
She also noted that results from one study suggested that a standing enucleation costs about 66% as much as enucleation performed under general anesthesia.
"Performing an enucleation in the standing horse is straightforward and allows the surgeon to avoid the potential complications associated with general anesthesia," Townsend concluded, noting that she prefers the standing procedure unless there are mitigating factors.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.