Heart rate and ECG response to twitching in Thoroughbred foals and mares.

This research studied the changes in heart rate and ECG in Thoroughbred foals and their mares in response to twitching, revealing that the effect was more significant in foals, with some showing A-V block cases at certain ages.

Objective and Methodology

• The research was conducted on 5 Thoroughbred foals of different ages and their mares. The aim was to observe the changes in the heart rate and Electrocardiogram (ECG) in response to twitching.
• Twitching in this scenario is a specific anatomical reaction in horses which provides an opportunity to understand the physiological response in horses, particularly changes in their heart rate and ECG.

Findings

• The study found that the decrease of heart rate in response to twitching was significantly greater in the foals than in their mares. This suggests that the physiological response of the foals was more vigorous compared to the mature horses.
• The decreased heart rate in the foals persisted during and after the incidences of twitching. This could indicate a longer duration of physiological impact due to twitching in foals compared to adult horses.
• Changes in the ECG specifically, the enhancement of the negative ingredient of the T wave, were observed in both foals and mares.
• The alterations in the T wave were accompanied by a decrease in the heart rate during and/or after the twitching in both sets of horses. This shows that the twitching can affect both the heart rate and ECG simultaneously.

Notable Observations

• Interestingly, 2 out of the 5 foals showed second-degree Atrioventricular (A-V) block following the decrease in heart rate during and/or after the twitching at the ages of 3.5 and 4 months and thereafter.
• An A-V block is a type of heart block in which the conduction between the atria and ventricles of the heart is impaired. This occurrence points towards a possible correlation between the physiological response to twitching and cardiac conductance in these younger animals.