Approximately 40 million working donkeys worldwide play key roles in the daily household economics of developing countries. These animals are responsible for pulling heavy loads in carts, often with improperly fitting harnesses that apply pressure on the neck. This can cause tracheal collapse and respiratory disease.

Carts fashioned for the approximately 10,000 donkeys in Meru County, Kenya, have a single shaft with a crossbeam attached to the donkeys proximal (closer to the base) to middle neck. “This means the weight of the entire cart is placed on the donkey’s ventral (underside of the) neck, directly overlying the trachea,” said Martha Mellish, DVM, Dipl. ACT, of the Department of Health Management at Atlantic Veterinary College, in Prince Edward Island, Canada.

Recognizing the impact of improperly fitting harnesses on the health and welfare of working donkeys, Mellish and colleagues investigated the presence of upper airway injury and tracheal collapse in both cart and pack donkeys at a Meru County health clinic. She presented their results at the 2024 American Association of Equine Practitioners Convention, held Dec. 7-11, in Orlando, Florida.

Performing Endoscopy in Working Donkeys

The team used an endoscope to evaluate each donkey’s trachea, and blinded reviewers evaluated the videos to grade tracheal collapse and identify tracheal ring abnormalities. The researchers also noted the presence of ventral neck skin and hair abnormalities on physical examination, which could indicate an improperly fitted harness.

Although performing an endoscopy on donkeys is more technically challenging than in horses, Mellish reported being able to grade tracheas with an average of 21 seconds of endoscopic video of the trachea. In total they reviewed 80 videos and recorded that 66 were considered diagnostic—38 from cart donkeys and 28 from pack donkeys. They considered some videos to be nondiagnostic if mucous obscured the camera lens or they could not pass the scope deep enough into the trachea.

Investigating the Effects of Harness Placement in Working Donkeys

The video reviewers identified a high prevalence of Grade 3 tracheal collapse—where the diameter of the trachea is reduced by 50% to 75%—occurring in almost 40% of the cart donkeys. They did not diagnose any cart donkeys with Grade 4 (full) tracheal collapse. In contrast, no pack donkeys had Grade 3 or 4 tracheal collapse.

“We also found a strong association between tracheal collapse and tracheal ring abnormalities and pulling carts,” said Mellish. “It is possible that the repeated trauma to the cervical trachea caused the endoscopic findings.”

These tracheal abnormalities, she said, are a significant welfare concern; affected donkeys might struggle to breathe, have low oxygen levels, or be reluctant to work. This in turn might result in prodding or maltreatment from the driver.

In addition, two-thirds of the cart donkeys had hair loss and thickened skin on the ventral neck, which was positively associated with tracheal collapse.

Take-Home Message

Mellish and her team found that 40% of cart donkeys experienced a significant reduction in trachea size, which has a direct impact on the animals’ welfare. However, they did not observe the tracheal changes in pack donkeys. “These findings are a foothold for improving harness and cart design to improve welfare in this community,” she said.