Primitive Gold Proves That EPM Doesn't Mean The End

Jun 8, 2009 - 10:00 PM

Ever had a day when your horse just didn’t feel quite right? Did you act on that feeling or ignore it? On a hot Virginia day in the summer of 1999, Linden Wiesman noticed that her partner, Primitive Gold, wasn’t acting quite like himself. Her prompt action may be the only reason he’s still competing today.

Primitive Gold suffered from sore heels after completing the Rolex Kentucky CCI*** in the spring, so the Thoroughbred gelding was already having a quiet summer. The injury forced Wiesman, of Bluemont, Va., to sit out the Pan Am Games, and “P.G.” was just returning to work when she noticed that he didn’t feel normal behind.

She loaded him into the trailer and went to see lameness specialist Kent Allen DVM at his Virginia Equine Imaging practice in Middleburg, Va. “He didn’t make it down the aisle twice before we saw neurological symptoms,” recalled Allen. “This was a horse we’d seen frequently, and he was moving with a very different gait than we’d seen before.” As P.G. trotted up and down the aisle, he was clumsy and uncoordinated behind, especially in the transition between the walk and the trot.

Proprioception is the sense that allows a horse to move in a circle without stepping on himself or a human to walk up stairs without looking at his or her feet, and P.G. was showing marked proprioception deficits. Because Allen had prior knowledge of P.G., he ruled out many causes for the neurological symptoms such as trauma to the neck. Although he was fairly certain that P.G. was showing signs of EPM, he suggested a spinal tap to make sure. The results confirmed his diagnosis, and the challenge was on to see if they could cure this special horse.

Pinpointing A Parasite

EPM is a neurological disease caused by a small single-celled protozoal parasite called Sarcocystis neurona. The disease doesn’t spread from horse to horse. Instead, the parasite lives in opossum feces and infects horses that consume contaminated feed or water. S. neurona attacks the horse’s central nervous system and causes an array of symptoms, including: ataxia (incoordination), spasticity (stiff, stilted movements), lameness, muscle atrophy, paralysis, seizures and difficulty swallowing.

There are many variables that play into how well a horse recovers from the disease. But one of the key factors is early diagnosis and treatment (see article “There’s More Than One Way To Fight EPM,” p. 28) before the organism has had the chance to damage much of the brain and spinal cord. Wiesman’s dedicated horsemanship and her regimen of veterinary care meant that no time was lost in diagnosing P.G.

He was immediately started on a six-month course of pyrimethamine and trimethoprin sulfa, which was the standard treatment for EPM in 1999. Allen also obtained an experimental drug from Canada, Baycox, which is now called Navigator. Killing the S. neurona parasite is the first step to recovery from EPM, but it’s by no means the end of the story.

P.G. did respond to the treatment, which was fortunate because as many as three out of 10 horses do not recover at all. But even the horses that do recover don’t always regain 100 percent of their original function. The central nervous system doesn’t repair itself, and even when the parasite is killed, the damage remains. No one wants to ride around a four-star cross-country course on a horse that’s only functioning at 90 or 95 percent of his capabilities. But Wiesman hadn’t come this far with P.G. to give up on him no matter how high the odds.

P.G. joined the Wiesman family in 1996 when they imported the flashy 6-year-old from England. He was originally intended for Jim, Linden’s father. As a youngster in England, P.G. had evented, foxhunted and competed in point-to-points. He was for sale because he’d begun to pull rails in the show jumping phase at intermediate.

Jim rode him for 1� years, but the thrill of another extreme sport, triathalon, called to him and he turned the talented horse over to his daughter. At first Wiesman wasn’t sure what to do with her father’s 17-hand behemoth. “He was like a boat to steer,” she said with a laugh. But they began to find a rhythm together and placed 10th at the Radnor CCI** (Pa.) in the fall of 1998. They continued to move up, finishing 13th at the 1999 Rolex Kentucky CCI***, although Wiesman was disappointed when they had three rails in the show jumping.

The Pan Am Games were out after P.G.’s bout with sore heels, but a four-star event certainly seemed to be in his future until the EPM diagnosis caused all of Wiesman’s plans to come to a grinding halt.

A Waiting Game

The only thing to do after administering the drug cocktail to P.G. was to wait and see how he responded. His symptoms did start to recede, and by November 1999 he’d improved immensely. A spinal tap at that time showed that the parasite was gone, but they weren’t out of the woods. Now they had to determine how much function P.G. had lost and whether he could return to the top of his sport. P.G. had time off while he was treated for EPM.

Allen said that the horse needed to focus his immune system on fighting off the parasite, and that physical exertion might have drained his limited resources. Wiesman started him back into work, but she still didn’t know if he was going to make a full recovery. His topline had deteriorated, and he had difficulty backing up under saddle, both results of the disease. The next three years were a roller coaster of ups and downs for Wiesman and P.G.

Focused on the Olympics in 2000 on another horse, Wiesman turned P.G. over to Emily Beshear née Mastervich. She took P.G. back in 2001 and rode him at the Fair Hill CCI*** (Md.), but small injuries kept them out of another three-day until the spring of 2003 when Wiesman rode P.G. in his first four-star at Kentucky. Unfortunately, he hit his stifle at the coffin and stopped at the water so she decided to retire him.

The inconsistent finishes and minor injuries wore on Wiesman, leaving her discouraged and wondering whether or not P.G. really could make it as a four-star horse. “I was always protecting the horse, trying to do everything for him,” she explained. “I was going out slow at horse trials, and I got into a backward, careful attitude.” In trying to keep P.G. safe and comfortable, she stopped practicing speed and found that when she tried to go fast at a three-day, neither one of them knew quite how to do it. It wasn’t until she began working with Phillip Dutton in 2003 that their performances started to improve.

Dutton encouraged Wiesman to be positive and get the job done. He helped her see that she wasn’t getting anything accomplished by trying to protect P.G. and pushed her to start riding forward again. They had a good finish at Fair Hill in 2003, but Wiesman still didn’t feel enthusiastic about attempting the spring four-star event. With Dutton’s encouragement, Wiesman tentatively set Rolex as her goal for 2004 with P.G.

Their 2004 spring season went well, with an early win in an advanced division at Pine Top (Ga.) bolstering her confidence. “We both have a little bit different attitude now. He started to try a lot more this spring,” she said of P.G. She focused on consistently improving their speed, getting faster at each event. “I’m still having time penalties,” she said laughing. “Just not as many!” When Rolex rolled around, Wiesman was ready.

She attacked the cross-country course and finished with a clear round and 14 time penalties. One rail in show jumping left her 14th in the four-star, an important victory for a horse that only had one three-star under his belt before battling EPM. Now Wiesman is daring to hope again, and she’s thinking about the Burghley CCI**** (England) in the fall.

The effects of the disease haven’t vanished from P.G.’s life altogether. He still has trouble backing up in a dressage test. Wiesman feeds him vitamin E and a folic acid supplement as well as a specialty grain called Horse Sense, which is packed with vitamins and nutrients to help boost his immune system. When P.G. starts preparing for a three-day, they put him back on the pyrimethamine and trimethoprin sulfa. He doesn’t have the parasite in his body, but he’ll always be more susceptible to it, so this drug cocktail helps protect him. Wiesman’s excited that she’s still able to compete P.G. at the highest levels, but she’s pragmatic about the effect of the disease on his life. “It’s one of those things you have to stay on top of,” she said. “I just try to keep him going in work and keep him happy.”

Category: Veterinary

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