OBJECTIVE: To describe the clinical and laboratory findings, diagnostic features, and outcome of tracheal collapse in American Miniature Horses at a referral institution. DESIGN: Retrospective case series. ANIMALS: 13 American Miniature Horses with tracheal collapse. PROCEDURES: Medical records of American Miniature Horses with tracheal collapse at a referral hospital were reviewed. Data extracted included signalment, history, clinical signs, laboratory data, diagnostic procedures, outcome, and histologic findings. RESULTS: Tracheal collapse was documented in 5.6% of American Miniature Horses admitted to this referral hospital. Median age at onset of clinical signs was 11 years with a range of 2 to 15 years. Common complaints and clinical signs included respiratory distress, tachypnea, inspiratory honking noises, and increased abdominal expiratory effort, which were exacerbated by stressful events, pregnancy, exercise, a dusty environment, and eating. Tracheal collapse was confirmed by use of radiography, endoscopy, fluoroscopy, or postmortem examination. Dorsoventral flattening of the extra- or intrathoracic trachea, or both, was more common than lateral collapse. Tracheal chondromalacia was identified histologically in 4 cases, and mortality rate for affected horses was 10 of 13. CONCLUSIONS AND CLINICAL RELEVANCE: Tracheal collapse was relatively common in this study of American Miniature Horses, and outcome was poor. The etiopathogenesis of the disease remains unknown.
OBJECTIVE: To describe the clinical and laboratory findings, diagnostic features, and outcome of tracheal collapse in American Miniature Horses at a referral institution. DESIGN: Retrospective case series. ANIMALS: 13 American Miniature Horses with tracheal collapse. PROCEDURES: Medical records of American Miniature Horses with tracheal collapse at a referral hospital were reviewed. Data extracted included signalment, history, clinical signs, laboratory data, diagnostic procedures, outcome, and histologic findings. RESULTS: Tracheal collapse was documented in 5.6% of American Miniature Horses admitted to this referral hospital. Median age at onset of clinical signs was 11 years with a range of 2 to 15 years. Common complaints and clinical signs included respiratory distress, tachypnea, inspiratory honking noises, and increased abdominal expiratory effort, which were exacerbated by stressful events, pregnancy, exercise, a dusty environment, and eating. Tracheal collapse was confirmed by use of radiography, endoscopy, fluoroscopy, or postmortem examination. Dorsoventral flattening of the extra- or intrathoracic trachea, or both, was more common than lateral collapse. Tracheal chondromalacia was identified histologically in 4 cases, and mortality rate for affected horses was 10 of 13. CONCLUSIONS AND CLINICAL RELEVANCE: Tracheal collapse was relatively common in this study of American Miniature Horses, and outcome was poor. The etiopathogenesis of the disease remains unknown.