Cervical Vertebral Stenotic Myelopathy

aka Wobblers

Introduction

Cervical vertebral stenotic myelopathy is an equine disease common in Thoroughbred horses between the ages of 6 months to 3 years. It is most typically seen in rapid growing colts.

Pathogenesis

Narrowing of the vertebral canal due to malalignment or maldevelopment of the vertebrae, causing progressive compression of the spinal cord.

There are two types of the disease:

(1) CVM Type 1 - Dynamic

This form is more common in younger horses. Spinal cord compression is caused by excessive movement of the vertebrae during flexion and extension of the neck. Vertebrae C3-C5 are most commonly affected.

(2) CVM Type 2 - Static

This form is more common in older horses, as a result of osseous change in the vertebrae. Vertebrae C5-C7 are most commonly affected.

Aetiology

The disease produces OCD (osteochondrosis dessicans)- like lesions on the vertebrae, producing an irregular joint surface. Nutrition is thought to play a part in the development of disease, with excessive protein and zinc, copper, calcium and phosphorous imbalances indicated as contributing factors. As horses with Cervical Vertebral Malformation appear to be more likely to develop OCD lesions in other joints there is thought to be a heritable component.

Clinical signs

Hind limb ataxia, spasticity and weakness are the main clinical signs. The development of these signs are normally insiduous

Cervicospinal Arthropathy

• = "Wobbler" in horses
• Usually presents in first two years of life
• Mainly in fast growing thouroughbreds
• Most common site is C3-C4, can occur anywhere
• Abnormal laxity between the vertebrae + cervical vertebral malformation may be evident
• Osteophyte formation at edges of synovial components of joint
• Some due to stenosis of neural canal later in life (1-4 years of age)
• Clinical signs:
  • Ataxia - hindlimbs more affected
• Presumed cause is rapid growth