Tracheal collapse rates in Kenyan working cart and pack donkeys.

Background: Donkeys (Equus asinus) in East Africa are recognised as working with poorly designed harnesses and carts. The donkey cart used in regions of Africa, specifically Meru County, Kenya, appears to place the cart's weight solely on the donkey's mid-cervical region. The ventral area of the neck is vulnerable to external pressure on the trachea, which is superficially located.

Objectives: To compare the presence and severity of endoscopic abnormalities in the upper airway and trachea of Meru County working cart donkeys compared to pack donkeys. To determine associations between endoscopic and physical evidence of harness injury.

Study Design: Cross-sectional.

Methods: At voluntary health clinics, physical examination and endoscopy of the upper airway and trachea were evaluated and recorded at rest on 66 donkeys (38 cart donkeys and 28 pack donkeys). The presence and grade of tracheal collapse, tracheal ring abnormalities, tracheal mucus, and pharyngitis were subsequently determined on the endoscopy recordings by blinded evaluators.

Results: Significant associations were identified between work type and tracheal collapse severity, ring abnormalities, pharyngitis, hairless skin, and thickened skin, with these findings more common in cart than pack donkeys (all p < 0.03). Moderate tracheal collapse (grade 3) was present in 40% (95% CI: 24%-57%) of cart and 0% (0%-12%) of pack donkeys. Intra-tracheal ring abnormalities were noted in 45% (29%-62%) of cart and 0% (0%-12%) of pack donkeys. Physical examination findings were significantly and positively associated with endoscopy findings (all p < 0.002).

Main Limitations: Standing endoscopy was performed at rest and dynamic endoscopy during the pulling of carts was not performed.

Conclusion: Moderate tracheal collapse was seen in cart donkeys when compared to pack donkeys. Physical examination findings at rest were associated with and moderately predictive of tracheal collapse.