Morphological study of tracheal shape in donkeys with and without tracheal obstruction.
Authors: Powell R J, du Toit N, Burden F A, Dixon P M
Journal: Equine veterinary journal
Summary
# Morphological Study of Tracheal Shape in Donkeys with and without Tracheal Obstruction Donkeys develop progressive structural changes in their tracheas with age, yet the clinical significance of these alterations remains poorly understood. Powell and colleagues examined 75 post-mortem tracheal specimens from predominantly geriatric donkeys (median age 30 years), measuring cross-sectional dimensions and classifying ring morphology across the 34–50 tracheal rings present in each animal, with particular attention to 12 donkeys that had shown clinical or pathological evidence of tracheal obstruction. Only 31% of the rings examined retained a normal circular to oval shape, whilst the remaining 69% exhibited various degrees of abnormality: dorsal ligament separation (24.4%), slight cartilage deformity (26%), moderate deformity (10.4%), and marked deformity (1.9%). Significantly, donkeys presenting with clinical dyspnoea or post-mortem obstruction evidence demonstrated substantially higher grades of tracheal abnormality than unaffected animals, and in three cases, concurrent lung disease appeared necessary to precipitate clinical signs. For practitioners managing geriatric donkeys, these findings suggest that moderate to severe tracheal structural changes are commonplace yet rarely symptomatic in sedentary animals—however, the presence of concurrent respiratory compromise, systemic illness or increased exercise demands may unmask previously subclinical obstruction and warrant closer airway assessment in aged animals with unexplained breathing difficulties.
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Practical Takeaways
- •Tracheal deformities are extremely common in aged donkeys but rarely cause problems in sedentary animals—do not assume abnormal tracheal anatomy is clinically significant without concurrent respiratory signs
- •When assessing an older donkey with dyspnoea, investigate for concurrent lung disease rather than assuming tracheal obstruction alone is responsible
- •Post mortem tracheal examination in aged donkeys should be expected to reveal structural abnormalities; their presence does not necessarily indicate antemortem clinical disease
Key Findings
- •Only 31.2% of tracheal rings examined had circular to oval shape; majority showed some degree of structural abnormality
- •Dorsal ligament separation occurred in 24.4% of rings and slight to marked cartilage deformity in 38.3% of rings across the donkey population
- •Donkeys with clinical or post mortem evidence of tracheal obstruction (12/75) had significantly increased tracheal abnormality grades compared to unaffected donkeys
- •Structural tracheal abnormalities are common in old donkeys but clinically silent unless concurrent pulmonary disease is present