Study: Some Wobbler-Affected Thoroughbreds Can Race

According to recent study, some carefully managed CVM horses could have active future

Cervical vertebral malformation (CVM) is considered, by some, a diagnosis that leaves a horse with little hope of an athletic career. But according to recent study results, some carefully managed CVM horses could have a productive future ahead of them, after all.

Veterinarians most commonly identify CVM, also known as wobbler syndrome, as a type of developmental orthopedic disease in young, rapidly growing horses. Affected horses have malformations in the spine leading to spinal cord compression, which in turn causes a lack of coordination of the limbs and weakness. Radiographs (X rays) can reveal a variety of spinal abnormalities associated with CVM, including kyphosis (curving of the spine), stenosis (narrowing of the spine), and a variety of lesions along the spine.

Treatment options for CVM include conservative management (such as modifying the horse's diet or using medical treatment to decrease inflammation) or surgical correction of the spinal compression.

Although CVM typically won’t directly kill a horse, many affected horses are euthanized. Study author Crystal Hoffman, DVM, an equine internal medicine resident at Virginia Tech's Marion DuPont Scott Equine Medical Center, said the reason for this high euthanasia rate is often linked to handler safety. Even with treatment, she said, many of these horses' neurologic deficits will only improve by one to two grades, making some potentially unsafe to handle.

But when horses respond well to treatment, they can have a full life ahead of them. Hoffman and researchers at the Peterson and Smith Equine Hospital, in Ocala, Fla., set out to determine which radiographic and neurologic exam findings indicate that affected horses might achieve athletic function with conservative management.

“Diagnosis of CVM does not necessarily equate to loss of use,” said Hoffman.

The team retrospectively reviewed the racing records of 119 Thoroughbreds diagnosed with CVM during an eight-year period and found that horses exhibiting mild neurologic signs and mild spinal deviations on radiographs, and that were managed conservatively were the most likely to make it to the track for at least one start. Mild deviations included caudal epiphyseal flare (an inflammation in the vertebrae similar to developmental orthopedic disease in joints) or extension of laminae in the spine, which researchers noticed resolved with growth. In fact, 30% of horses with these clinical signs eventually raced. On average, horses that did not make it to the track had more severe neurologic signs.

Conservative management of the successful horses was focused on decreasing inflammation using oral or intravenous anti-inflammatories and corticosteroids, and dimethylsulfoxide (DMSO); minimizing concussion to the spinal cord by restricting turnout to small paddocks; and managing horses' growth rate via nutritional changes to prevent damage to the area.

Radiographs revealed that horses with a visible over-curvature of the back or spinal cord narrowing were less likely to make a racing start. These types of changes resulted in more severe clinical signs that were less likely to respond to conservative management.

Other issues, such as bone cysts, did not significantly impact a horse’s prognosis, the team noted.

“It's difficult to determine the prognosis for the horse, especially on initial evaluation when there was some sort of acute trauma that led to inflammation and the horse's sudden neurologic signs,” said Hoffman. “That is part of why we performed this study: to determine what their prognosis would be based on neurologic signs and radiographic findings.”

The study, "Prognosis for racing with conservative management of cervical vertebral malformation in thoroughbreds: 103 cases (2002-2010)," appeared in the March/April issue of the Journal of Veterinary Internal Medicine

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.