We usually associate dehydration with hot, humid weather, but it can occur at any time. In fact, winter dehydration is common in horses because they don't like to drink very cold water. To prevent or reverse mild dehydration, get your horse to drink more water.
Sign of equine dehydration include:
• Dry mucous membranes of the inner eye lid and gums
• Sunken eyes
• Fatigue and weak pulse
• Elevated heart and respiratory rates
Tests that you can perform include the CRT (capillary refill time), skin tenting and jugular vein refill speed. You should be familiar with your horse's healthy, baseline readings in order to interpret the results of these tests.
CRT Test: Press your horse's gum lightly. The skin will blanch as blood is pushed away from the site. Color should return to normal within 2 seconds.
Skin Tenting Test: Pinch the skin on the front of your horse's shoulders, near the neck. The skin should spring back quickly.
Jugular Vein Refill Speed Test: Press the large vein that runs the length of your horse's neck (the jugular). It will reform quickly in a hydrated horse.