There are a few areas on the body that provide a window into the state of a horse's circulatory health. These areas include the gums, the pink membrane inside the nostril, the whites of the eyes, and the pink inner vulvar membranes of mares. The simple act of evaluating your horse's gums is a very important skill.

Normal mucous membranes should be moist, pink and glistening. Dry gums and membranes of the mouth, either pale or dark colored, can indicate shock or dehydration. But like many observations, this needs to be interpreted in light of the other signs the horse is showing.