Observations on tracheal mucociliary clearance in horses

Area of Science:

• Veterinary Medicine
• Respiratory Physiology
• Nuclear Medicine Imaging

Background:

• The mucociliary escalator is a primary defense mechanism in the respiratory tract.
• Impaired mucociliary transport is associated with respiratory diseases in equines.
• Technetium-99m labeled macroaggregated albumin (MAA) is a radiotracer used to assess lung function.

Purpose of the Study:

• To quantify and compare the mucociliary transport rate in normal horses versus horses with respiratory disease.
• To evaluate the utility of Technetium-99m MAA in assessing equine respiratory health.

Main Methods:

• Seven normal horses and eight horses with respiratory disease were included.
• Technetium-99m MAA was instilled, and its movement was tracked using a handheld scintillation counter.
• Activity was measured at two cervical sites (12-15 cm apart) to determine transport rate.

Main Results:

• Normal horses exhibited a mean transport rate of 1.58 cm/min, with MAA moving as a discrete bolus.
• Horses with respiratory disease showed a reduced mean transport rate of 1.19 cm/min.
• In diseased horses, MAA movement was less consistently bolus-like, and transport rate could not be determined in three individuals.

Conclusions:

• Respiratory disease in horses is associated with significantly impaired mucociliary escalator function.
• Technetium-99m MAA scintigraphy is a viable method for assessing mucociliary transport in horses.
• This technique can aid in the diagnosis and management of equine respiratory conditions.