Quantitative intradermal terbutaline sweat test in horses.

The research investigates the impact of a drug called terbutaline on the sweat levels of healthy Thoroughbred horses when administered intradermally. The study found that the terbutaline concentration significantly influenced sweat weight, but environmental factors and time of year had no noteworthy effect.

Research Approach

• The researchers aimed to understand and quantify the impact of terbutaline on equine sweating. Terbutaline is commonly used in human medicine as a bronchodilator to help manage asthma, and its use in horses is of interest to the researchers in understanding its impacts on their physiology.
• Seven Thoroughbred horses served as the subjects of this study. Thoroughbreds were chosen due to their popularity in equestrian sports and their susceptibility to certain health issues.
• The preparation of terbutaline involved diluting it across ten-fold, starting from 1000 mg/l down to 0.001 mg/l.

Methods

• The diluted terbutaline and a saline control were administered intradermally, which means they were injected directly into the dermis, the intermediate layer of skin.
• Sweat was collected for 30 minutes use absorbent pads that were taped over each injection site.
• The experiment ran monthly for 11 months, during which the temperature, relative humidity and dew point were measured simultaneously.

Key Findings

• The results showed that the time of year and environmental variables (like temperature, humidity, and dew point) had no significant impact on the horses’ sweat responses.
• However, the concentration of the intradermal terbutaline significantly affected the sweat weight. Starting at a concentration level of 0.1 mg/l, sweat weight increased significantly with each increase in terbutaline concentration up to 1000 mg/l.

Conclusion and Applications

• The findings suggest that terbutaline affects sweat production significantly in horses and these effects can be quantitatively measured through the described sweat test.
• The authors propose that the terbutaline sweat test could be used as a diagnostic tool in the study of equine sweating and anhidrosis — a condition where a horse is unable to sweat effectively.