Introduction

• Cause: oronasal fistula is a congenital or acquired communication between the oral and nasal cavities.
• Congenital fistulae (cleft palate) may be caused by numerous etiological agents acting at a susceptible stage of gestation. Additional associated abnormalities, eg harelip may also be present.
• Acquired oronasal fistulae are caused by trauma or disease.
• Signs: relate to the oral and nasal cavities, and sometimes to the chest if secondary pneumonia is present.
• Diagnosis: usually straightforward, based on history and clinical signs.
• Treatment: reconstructive surgery.
• Prognosis: favorable, although euthanasia of congenitally affected neonates is often performed.

Pathogenesis

Etiology

• The following are possible etiologies:
  • Inheritance: incomplete dominant, recessive or polygenic traits.
  • Infectious disease.
  • Nutritional factors.
  • Mechanical factors: uterine overcrowding, uterine trauma.
  • Toxic factors.
  • Hormonal factors.
• It may not be possible to determine the precise cause of congenital fistulae.
  Acquired fistulae
• Common causes are:
  • Advanced periodontal disease Periodontal disease.
  • Trauma.
  • Oral neoplasia Mouth: neoplasia.
  • Iatrogenic.

Pathophysiology

• Congenital fistulaehave multiple etiologies:
  • The etiological agent must act at the appropriate stage of fetal development when the palate is developing and closing.
  • In dogs, this is thought to be at gestation days 25-28.
• Acquiredfistulae are associated with:
  • Degenerative, eg oral/dental infection.
  • Infiltrative, eg oral neoplasia disease.
  • Direct trauma.

• Most common scenario is progressive dental disease resulting in lysis of the thin alveolar bone plate at the apex of the alveolus. Communication is then established between the oral cavity and the nasal cavity.
• Traumatic dental extraction technique Dental extraction can result in disruption of the thin alveolar bone, which may already be devitalized.

Timecourse

• Weeks to months.

Diagnosis

Treatment

Outcomes