Wobblers syndrome

Veterinary advice should be sought before applying any treatment or vaccine.

Wobblers Syndrome

Cervical Vertebral Malformation, Cervical Vertebral Compressive Myelopathy (CVCM),Cervical Vertebral Instability

Wobblers syndrome, or "Wobblers", is a neurological disease of horses that causes compression of the spinal cord, resulting in ataxia involving all four legs. There are over 14 different names used to describe the disease, mainly caused by confusion as to the underlying mechanisms involved with its onset. Some of the most commonly used names include CVM - cervical vertebral malformation, CVCM - cervical vertebral compressive myelopathy, CVI - cervical vertebral instability, and CSM - cervical stenotic myelopathy.

Clinical signs of wobblers can be identified in horses at an early age, in some instances before 3 months of age. Wobblers can also occur in older horses, caused by arthritic changes involving the articular process joints and intervertebral bodies. In many affected horses, the onset of clinical signs are acute, despite the slow progressive nature of arthritis. Horses with wobblers are often described by their owners as acting 'increasingly clumsy' or "drunk". The most common signs observed in affected horses include symmetric ataxia, paresis, and spasticity involving all four legs, but most pronounced in the pelvic limbs. These horses often routinely loose coordination and have an uneven stride length and height.

When neurological disease is suspected by your veterinarian, they will usually conduct a neurological examination on the horse. A neurological examination consists of a serious of mini tests used by veterinarians to better assess the type of neurological involvement. These tests include:
  • Observation of the horse walking in a straight line: A test used to assess for signs of weakness, such as stumbling, dropping of the hip during the stride, dragging the toe, knuckling, varying stride length, swaying of the limbs or body (truncal sway), or floating of the limbs in the air.
  • Observation of the horse walking in a tight circle: A test used to assess for the presence of outward swaying of the pelvic limb on the outside of the circle. The horse's head is usually kept elevated while walking, in order to exacerbate the signs and may cause the horse to start pacing.
  • Tail-pull test: A test used to assess pelvic limb strength in the horse. Your veterinarian will pull the horse's tail a special way, while the it is standing at rest as well as while walking.
  • Observation during walking backwards: A test used to observe whether the horse is having a difficult time backing up, as horses with spinal cord damage often can only drag the limbs backward slowly, and are usually unable to back up without difficulty.
Wobblers is thought to be a multifactorial disease, consisting of genetic predisposition and environmental influences (such as nutritional balance, rapid growth, abnormal biomechanical forces, and physical trauma.

The type of spinal cord compression that occurs in horses with wobblers can be dynamic or static:
  • Dynamic compression: Tends to affect young horses between six months and two years of age. It is caused by abnormal bone development of the first four vertebrae and occurs only when the horse flexes or extends its neck. This form usually affects the hindlimbs more severely but is noted to occur in all four limbs.
  • Static compression: It is caused by bone and soft tissue abnormalities and usually involves the fifth and seventh cervical vertebrae. This form of compression generally affects the horse's forelimbs more severely.
Wobblers Vs. Equine Protozoal Myeloencephalitis (EPM)
Clinical signs of horses with Equine Protozoal Myeloencephalitis (EPM) may appear similar to Wobblers. Both diseases cause spinal ataxia, however many horses with EPM have asymmetric ataxia as well as additional lower motor neuron signs (muscle atrophy), and signs of brain and brainstem involvement (head tilt, facial paralysis, cranial nerve signs, blindness).

Wobblers Vs. Equine Herpes Myeloencephalopathy (EHM)
Equine Herpes Myeloencephalopathy (EHM) is a neurologic manifestation of Equine Herpesvirus-1 infection. Clinical signs of EHM can sometimes appear very similar to Wobblers. However, when horses are affected by EHM they will often usually also have a history of fever, along with weakness, symmetric ataxia (which frequently ascends up the pelvic limbs), poor tail tone, bladder dysfunction with urinary incontinence and sometimes will progress to recumbency and death. Usually with EHM, multiple horses are affected at or near the same time. With wobblers, usually only one horse is affected.

Treatment Goals
The treatment goal of medical management of horses with wobblers is to minimize swelling and inflammation in the spinal cord.

Symptoms

Ataxia
Abnormal gait
Weakness
Spasticity involving all four limbs
Stumbling
Reluctant to rise or falls easily
Truncal sway
Difficulty walking backwards
Uneven stride and height
Base-wide stance
Toe dragging
Knuckling

Diagnosis

  • History
  • Clinical signs
  • Neurological exam
  • Radiographs - A lateral radiograph of the cervical vertebrae in order to calculate the sagittal ratio (obtained by dividing the minimum sagittal diameter of the vertebral canal by the width of the corresponding vertebral body.

Treatment

TherapiesDetails
Stall rest
NSAIDS
Surgical correctionThe best treatment has typically been ventral interbody fusion, which is a modification of the Cloward technique, used in humans where it is referred to as anterior interbody fusion technique. This procedure has been used in horses with Wobblers since 1979.

Prevention

Prognosis

Dependent on the number and location of vertebrae affected, age of the horse, severity of symptoms, and delay between onset of symptoms and treatment

Scientific Research

General Overviews

Clinical Trials

Risk Factors

  • Thoroughbreds Are Predisposed (with A Prevalence Of 2%)
  • Horses Which Experience Rapid Growth And Are Larger Than Most Horses Their Same Age/breed.