Researchers are still pondering the cause of this lymph vessel problem that can result in long-lasting effects after the initial insult.

At the end of the 2005 show season, Jen Gorsuch of Medinah, Ohio, anticipated an uneventful off season for her then-11-year-old Saddlebred mare, Aruba. Unfortunately, that wasn’t to be the case. Just one day after having her horse’s show shoes removed, Gorsuch noticed that something was very wrong with Aruba’s left hind leg.

"We had taken her show shoes off and put her in her stall for the night," Gorsuch recalled. "The next morning, when we took her out of her stall, her leg was swollen from the ankle to the stifle. She’d never stocked up, and she doesn’t kick, so we thought she had broken her leg."

Gorsuch didn’t know it at the time, but Aruba was exhibiting classic clinical signs of lymphangitis, an inflammation of the lymph vessels that results in lasting effects long after a horse’s recovery.

"One of the troubling things about lymphangitis is that we really aren’t sure what causes it," says Rose Nolen-Walston, DVM, Dipl. ACVIM, assistant professor of medicine at the University of Pennsylvania’s School of Veterinary Medicine at New Bolton Center. "Sometimes owners mistake it for stocking up."

According to Nolen-Walston, lymph vessels, which are part of the lymphatic system, are found throughout the body, like arteries and veins. Lymph fluid–which is squeezed through the body by muscle action–picks up breakdown products from damaged areas in the body and removes toxins alon