Editor's Note: This article is part of TheHorse.com's ongoing coverage of topics presented at the British Equine Veterinary Association's 51st annual Congress, held Sept. 12-15 in Birmingham, U.K.
In recent years, owners and veterinarians have become more aware of the articular process joint disease called cervical vertebral compressive myelopathy (CVCM, which in younger horses is known as wobbler syndrome), and researchers have made progress in understanding it better.
This could be due to several reasons, said Richard Hepburn, BVSc, MS(Hons), CertEM, Dipl. ACVIM(LA), MRCVS, of the B&W Equine Hospital, in Gloucestershire, U.K. He explained his theories as well as the characteristics of this disease at the British Equine Veterinary Association's 51st annual Congress, held Sept. 12-15, in Birmingham, U.K.
"Articular process joint disease is the commonest noninfectious cause of spinal ataxia (incoordination)," Hepburn said. Practitioners categorize affected horses by neurologic signs from grade 0 to 5, with most horses showing moderate neurologic signs (grade 2-3).
One reason Hepburn listed for its seemingly increased prevalence is that horses are living longer. Also, there has been a rise in the popularity of large breeds, such as Warmbloods, which are more predisposed to developing CVCM. Further, he noted that training methods have evolved requiring horses to use certain neck positions that could potentially contribute to this disease.
In describing CVCM, Hepburn divided the condition into two categories: type 1 in younger horses experiencing developmental disease and, more commonly, type 2 in horses older than 8 suffering from osteoarthritis.
In both groups compression of the cervical spine causes functional and then physical degeneration, leading to neurologic signs such as ataxia and paresis (weakness), Hepburn explained.
In young horses this condition is most commonly seen in Thoroughbred and Warmblood geldings. The compression is caused by a combination of vertebral canal narrowing and abnormal vertebral joint development.
In managing these horses, Hepburn suggested working with a veterinarian to administer corticosteroids and dimethyl sulfoxide (DMSO) to reduce nerve cell swelling, supplementing vitamin E, and providing stall rest. In horses younger than one year, he suggested a low nonstructural carbohydrate diet program (because researchers also believe high-carb diets contribute to the disease) as well as strict stall rest and vitamin E supplementation. This "paced diet program" can allow normal growth of the vertebral bones to resolve the spinal cord compression.
Hepburn noted that in some young horses abnormal vertebral joint development alone causes the spinal cord compression. In this population a novel approach he described is intra-articular (IA) corticosteroid administration. Approximately 60% of cases treated with this method see significant neurologic improvement and have a normal athletic future, he said.
Older horses, Thoroughbred/Thoroughbred crosses, Quarter Horses, and male Warmbloods appear to be more predisposed to CVCM than other breeds, Hepburn observed.
"These cases have a history of poor performance (unbalanced, refusing to jump or go forward, weak behind, reduced suppleness) and can be reported to stumble and trip, particularly downhill," he said. They too show signs of multilimb ataxia and paresis.
In this population the spinal cord compression is caused by osteoarthritic enlargement of the vertebral joints. Hepburn suggested treating these horses with IA corticosteroid therapy. Based on his experience, "approximately 80% of cases improve two neurological grades (with corticosteroid treatment), which typically returns the horse to normal," he said. However, "signs usually recur after two to four years, when repeat therapy will be equally effective provided significant radiographic progression has not occurred."
Regardlessof the type of CVCM, many of these cases can be managed successfully, thanks to owners, trainers, and veterinarians being more aware of the disorder, Hepburn said. If your horse shows neurologic signs consistent with this condition, contact your veterinarian to start immediate treatment and work toward halting the disease process.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.