Changes

Also Known As: '''''Wobblers — Cervical Vertibral Malformation — Cervical Vertebral Stenosis'''''

Also Known As: '''''Wobblers — Cervical Vertebral Malformation — Cervical Vertebral Stenosis — CVM — Equine Stenotic Myelopathy'''''

==Introduction==

==Introduction==

==Pathogenesis==  

==Pathogenesis==  

A '''narrowing''' of the '''vertebral canal''' due to '''malalignment''' or '''maldevelopment of the [[Spinal Column - Anatomy & Physiology|cervical vertebrae]]''', causing '''progressive compression of the spinal cord'''.

A '''narrowing''' of the '''vertebral canal''' due to '''malalignment''' or '''maldevelopment of the [[Spinal Column - Anatomy & Physiology|cervical vertebrae]]''' causes '''progressive compression of the spinal cord'''.

There are two types of the disease:

There are two types of the disease:

'''(1) Type 1 CVM — Dynamic'''

'''(1) Type 1 CVM — 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''' and is therefore '''dynamic''' in nature. Vertebrae '''C3-C5''' are most commonly affected.

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''' and is therefore '''dynamic''' in nature. Vertebrae '''C3-C5''' are most commonly affected.

'''(2) Type 2 CVM — Static'''

'''(2) Type 2 CVM — Static'''

 

:This form is more common in '''older''' horses, as a result of '''osseous change''' in the vertebrae. The spinal cord is constantly compressed. Vertebrae '''C5-C7''' are most commonly affected.  

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

==Aetiology==

==Aetiology==

The disease produces '''[[Osteochondrosis|OCD]]-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 [[Osteochondrosis|OCD]] lesions in other joints there is thought to be a '''heritable''' component.  

The disease produces '''[[Osteochondrosis|OCD]]-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 [[Osteochondrosis|OCD]] lesions in other joints there is thought to be a '''heritable''' component.  

==Clinical signs==

==Clinical Signs==

'''Hind limb ataxia''', '''spasticity''' and '''weakness''' are the main [[Site of Spinal Lesions Determination - Horse|clinical signs]]. The development of these signs are normally '''insidious''' but may come about suddenly following trauma. Ataxia is normally '''bilateral''' and '''symmetrical'''. Forelimbs may also be affected.

'''Hind limb ataxia''', '''spasticity''' and '''weakness''' are the main [[Site of Spinal Lesions Determination - Horse|clinical signs]]. The development of these signs are normally '''insidious''' but may come about suddenly following trauma. Ataxia is normally '''bilateral''' and '''symmetrical'''. Forelimbs may also be affected.

'''Subjective''' radiographic signs:

'''Subjective''' radiographic signs:

* Spinal cord mal-alignment

* Spinal cord mal-alignment

* [[Degenerative Joint Disease|Osteoarthritis]] of articular processes

* [[Degenerative Joint Disease|Osteoarthritis]] of articular processes

'''Objective''' radiographic signs:

'''Objective''' radiographic signs:

 

* Intravertebral ratios

**Minimum saggital diameter of spinal canal divided by the maximum dorsoventral height of the same vertebral body.

* Intervertebral ratios

* Intervertebral ratio:

If the radiographs are of a high quality, a combination of these signs should be sufficient to make the diagnosis of CVM.

If the radiographs are of a high quality, a combination of these signs should be sufficient to make the diagnosis of CVM.

Abscesses, tumours, synovial cysts, ligamentar hypertrophy and trauma may not show signs radiographically despite producing       the clinical signs of CVM.  

Abscesses, tumours, synovial cysts, ligamental hypertrophy and trauma may not show signs radiographically despite producing the clinical signs of CVM.  

'''Myelography''' is generally only indicated in potential '''surgical''' cases.

'''Myelography''' is gold-standard ante-mortem diagnostic procedure to document location of spinal cord compression.

*It is generally only indicated in potential '''surgical''' cases but also essential to create a surgical plan.

==Differential Diagnosis==

==Differential Diagnosis==

* Equine Degenerative Myeloencephalopathy

* Equine Degenerative Myeloencephalopathy

* Trauma

* Trauma

* Migrating strongyles - rare now due to ivermectin treatment

* Migrating [[strongyles]] - rare now due to ivermectin treatment

* [[Polyneuritis Equi|Polyneuritis equi]]  

* [[Polyneuritis Equi|Polyneuritis equi]]  

* Ryegrass staggers

* Ryegrass staggers

* [[Equine Protozoal Myeloencephalitis|Equine Protozoal Myeloencephalitis]] - in foreign imports

* [[Equine Protozoal Myeloencephalitis|Equine Protozoal Myeloencephalitis]] - in some countried or imported horses

* Neoplasia

* Neoplasia

==Treatment==

==Treatment==

The mainstays of treatment are '''box rest''' (for several months), '''anti-inflammatories''' ([[NSAIDs|NSAIDS]]), and '''dietary adjustment''' (to a low protein diet to slow the growth of the horse, allowing the canal growth to 'catch up').

The mainstays of treatment are '''box rest''' (for several months), '''anti-inflammatories''' ([[NSAIDs|NSAIDS]]), and '''dietary adjustment''' for type 1 (to a low protein diet to slow the growth of the horse, allowing the canal growth to 'catch up').

'''Surgery''' can be performed. This involves ventral stabilisation of the vertebrae using a steel or titanium implant.

'''Surgery''' can be performed. This involves ventral stabilisation of the vertebrae using a steel or titanium implant.

==Prognosis==

==Prognosis==

Horses with a '''grade 1''' ataxia on the Mayhew scale may retain '''athletic''' function. Conservative treatment in mildly affected horses normally improves clinical signs and surgery may improve the ataxia score by one or two grades on the Mayhew scale.

Horses with a '''grade 1''' ataxia on the [[Body, Spinal Cord and Limb Neurological Examination - Horse#Gait|Mayhew scale]] may retain '''athletic''' function. Conservative treatment in mildly affected horses normally improves clinical signs and surgery may improve the ataxia score by one or two grades on the Mayhew scale.

{{Learning

{{Learning

May, SA & McIlwraith, CW (1998) '''Equine Orthopaedics and Rheumatology Self-Assessment Colour Review''' ''Manson Publishing Ltd''

May, SA & McIlwraith, CW (1998) '''Equine Orthopaedics and Rheumatology Self-Assessment Colour Review''' ''Manson Publishing Ltd''

[[Category:Joints - Degenerative Pathology]]

[[Category:Joints - Degenerative Pathology]]

[[Category:Bones - Developmental Pathology]]

[[Category:Bones - Developmental Pathology]]

[[Category: To Do - Siobhan Brade]]

[[Category:Musculoskeletal Diseases - Horse]]

[[Category:To Do - Manson review]]

[[Category:Neurological Diseases - Horse]]

[[Category:Expert Review - Horse]]