According to Dr. John Baird, professor emeritus at the Ontario Veterinary College in Guelph, who specializes in equine dermatology, gastroenterology, renal and hepatic diseases, red maple leaves (Acer Rubrum), especially wilted ones, are extremely poisonous to horses, along with alpacas.

The leaves cause serious damage to horse’s red blood cells once absorbed into its digestive system.

“The damage to the red cells results in the horse becoming depressed, weak, lethargic, and their respiratory rate is increased,” he wrote in an email.

He said symptoms of red maple toxicosis usually start to show within one to two days of the leaves being consumed and that anywhere between 1.5 to three pounds worth of leaves can cause the disease.

Baird said 60 per cent of horses that come down with the disease die.

He said more horses tend to get the disease during the summer and fall when the leaves are on the trees and have fallen to the ground.

While removing the trees or not planting them where horses graze is the best way to protect animals, Baird said ranchers can take further steps.

“Owners should be aware that following storms branches of maple trees may be blown or fall into horse paddocks,” he wrote.

Swift, who treated her horse like family, hopes other horse owners will learn from her loss so they don’t have to go through the same heartbreak.

“She was really looking good and we were going to a show this summer,” she said. “It just shouldn’t have happened.”

For additional information on toxic plants and horse health management, visit the Ontario Ministry of Agriculture, Food and Rural Affairs at http://omafra.gov.on.ca/english/livestock/horses/health.html.