Oxygen cost of ventilation in the resting horse.

The research aimed to establish a method to measure the oxygen cost of ventilation and the values of ventilatory parameters in horses under resting conditions while rebreathing carbon dioxide (CO2). The study concluded that the CO2 rebreathing test was a successful non-invasive procedure to measure these parameters.

Objectives of the Research

• Develop a technique to measure the oxygen cost of ventilation and the ventilatory parameters when horses are in a resting state rebreathing CO2.
• Understanding the physiological aspects of horses’ ventilatory response to CO2 inhalation.

Execution of the Research

• The research was performed with seven normal horses.
• The horses were exposed to increased inspiratory levels of CO2.

Findings from the Research

• Upon experiencing higher levels of inhaled CO2, the horses responded by increasing their tidal volume (VT) which represents the normal volume of air displaced between normal inhalation and exhalation, and frequency of breathing (Vf), two significant parameters of ventilation.
• The researchers were able to determine the oxygen cost litre-1 of ventilation, which means the quantity of oxygen required for ventilation per litre. This was measured at ventilation rates exceeding 200 litres per minute, and averaged at 1.7 (0.04) ml litre-1, a result that is comparable to that of human subjects undergoing submaximal ventilation.

Conclusions from the Research

• Based on these findings, the study concluded that the CO2 rebreathing test is an effective and non-invasive way of measuring the oxygen cost of breathing and ventilatory response to CO2 in horses.
• Notably, such studies help scientists to gain insights into the respirational behaviour of horses which could contribute to better veterinary care and management of equine health, especially during conditions that might cause respiratory stress.