Canis ISSN: 2398-2942

Spine: butterfly vertebrae

Synonym(s): Congenital spine anomaly

Contributor(s): Laurent Garosi

Introduction

  • Cause: abnormal vertebral development mostly seen in brachycephalic, screw-tailed breeds.
  • Signs: rarely clinically significant, incidental finding on survey radiograph. However, clinical myelopathies associated with butterfly vertebrae are generally traumatic or compressive and occur as a result of malformation or instability of the vertebral column. They are often treatable.
  • Diagnosis: radiography.

Pathogenesis

Etiology

  • No known specific cause but associated with screw-tailed breeds, therefore may be genetically transmitted.

Predisposing factors

General
  • Presently unknown.

Specific

  • Presently unknown.

Pathophysiology

  • Malformation originating in the embryonic period of development.
  • Butterfly vertebra is a vertebral body/intervertebral disk abnormality which is mesodermal in origin.
  • Result from incomplete intradiskal migration of notochordal material resulting in bificentrum formation.
  • Persistence of the embryonic notochord, or its sagittal cleavage, may produce a sagittal cleft of the vertebral body dorso-ventrally.
  • The cranial and caudal vertebral end-plates have a funnel shape and in dorso-ventral radiographs, the vertebral body looks like a butterfly.
  • The butterfly vertebra is also characterized by lateral spread of its two halves and compensatory growth of the adjacent normal vertebrae to fill in the funnel-shaped depressions.
  • Improper embryogenesis → abnormal growth and development → some narrowing of vertebral canal → pressure on cord in area.
  • If the vertebral body is very diminutive it may result in kyphotic angulation, especially if associated with centrum hypoplasia.

Timecourse

  • When clinical signs occur, onset is typically acute (hours, days).

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Gutierrez-Quintana R, Guevar J, Stalin C et al (2014) A proposed radiographic classification scheme for congenital thoracic vertebral malformations in brachycephalic "screw-tailed" dog breeds. Vet Radiol Ultrasound. 55 (6), 585-91 PubMed.
  • Westworth D R, Sturges B K (2010) Congenital spinal malformations in small animals. Vet Clin Small Anim 40 (5), 951-981 PubMed.
  • Bailey C S & Morgan J P (1992) Congenital spinal malformations. Vet Clin North Am Small Anim Pract 22 (4), 985-1015 PubMed.
  • Braund K G, Shores A, Brawner W R Jr. (1990) The etiology, pathology and pathophysiology of acute spinal cord trauma. Vet Med 85 (7), 684-691 VetMedResource.

Other sources of information

  • Braund K G (1994)Clinical Syndromes in Veterinary Neurology.2nd edn. St. Louis. Mosby Year Book. pp 280-281.
  • Oliver, Hoerlein & Mayhew (1987)Veterinary Neurology.pp 203.
  • Bojrab M J (1983)Disease Mechanisms in Small Animal Surgery.2nd edn. Lea & Febiger. pp 954.


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