Hemivertebra

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Radiograph of multiple hemivertebrae with one-sided fused vertebral bodies[1]

Hemivertebra (hemi = half) is a congenital vertebral malformation of dogs characterized by 'wedge-shaped' vertebra[2].

Hemivertebra is commonly in screw-tailed breeds (Pug, Bulldog, Boston Terrier), in which it is responsible for the kink in the tail and is usually nonpathogenic apart from a slighter risk of intertrigo.

Typically, hemivertebra involves a single vertebra anywhere along the spine, but some involve numerous contiguous vertebrae causing severe malformations such as scoliosis and kyphosis resulting in lameness and proprioceptive deficits due to spinal cord compression[3][4].

Cervical hemivertebra are also implicated in cervical vertebral instability associated with Wobbler syndrome in Dobermans[5].

The condition is characterised clinically by progressive hind-leg weakness, spinal pain, abnormalities of the nervous system and evidence of muscle atrophy or other abnormalities of conformation[6].

Diagnosis is usually achieved by lateral and dorsoventral radiographs, CT or MRI imaging. In cases with neurological signs, myelography is warranted as an adjunct diagnostic tool.

Treatment in moderate cases requires hemilaminectomy to relieve spinal cord compression, which in most cases is curative[7].

References

  1. Marista Vet
  2. Besalti O et al (2005) Nasca classification of hemivertebra in five dogs. Ir Vet J 58(12):688-690
  3. Kramer JW et al (1982) Characterization of heritable thoracic hemivertebra of the German shorthaired pointer. J Am Vet Med Assoc 181(8):814-815
  4. Moissonnier P et al (2011) Thoracic kyphosis associated with hemivertebra. Vet Surg 40(8):1029-1032
  5. McKee WM & Sharp N (2003) In: Textbook of Small Animal Surgery. Third. Slatter D, editor. Vol. 1. Philadelphia: Saunders. Cervical spondylopathy. pp:1180–1193
  6. Done SH et al (1975) Hemivertebra in the dog: clinical and pathological observations. Vet Rec 96(14):313-317
  7. Kirberger RM (1989) Congenital malformation and variation of the lumbar vertebrae in a dog. J S Afr Vet Assoc 60(2):111-112