Exercise-induced pulmonary perfusion redistribution in heaves

Area of Science:

• Equine respiratory physiology
• Nuclear medicine in veterinary diagnostics

Background:

• Equine asthma ('heaves') significantly impacts respiratory function.
• Understanding pulmonary perfusion changes during exercise is crucial for diagnosing and managing equine respiratory diseases.

Purpose of the Study:

• To compare exercise-induced pulmonary perfusion redistribution in healthy horses versus horses with 'heaves' using scintigraphy.
• To evaluate the feasibility of scintigraphy for assessing pulmonary perfusion dynamics in equine athletes.

Main Methods:

• Scintigraphy was employed to image pulmonary perfusion (Q) in healthy horses and horses with 'heaves' (in remission and during clinical signs) at rest (QR) and during exercise (QE).
• Quantitative analysis of QE/QR ratios defined regions of increased perfusion (R1) during exercise.
• Lung dimensions, particularly height, were measured from the scintigraphic images.

Main Results:

• Exercise induced significant pulmonary perfusion redistribution in all horses.
• Horses with 'heaves' exhibited a larger R1 region and higher QE/QR ratios, indicating intensified perfusion redistribution, particularly to the dorsal lung regions.
• A greater increase in lung height during exercise was observed in 'heavey' horses.

Conclusions:

• Scintigraphy is a feasible and valuable tool for studying exercise-induced pulmonary perfusion redistribution in horses.
• Pulmonary perfusion redistributes to the dorsal lung regions during exercise in horses.
• Horses with 'heaves' demonstrate an intensified pulmonary perfusion redistribution pattern, regardless of clinical status.