The level of hydration (or dehydration) in a horse is an important indicator of health or illness. Hydration is reflected in the amount of water within the connective tissue under the skin.
A “skin pinch” is therefore used as a rough estimate of hydration, and is used in conjunction with other findings in the evaluation of a horse’s circulatory health.
How long the skin takes to flatten back out after being pinched up relates to how much fluid there is in the connective tissues under the skin.
In a well hydrated horse, the return should be almost immediate. The longer the skin remains tented (retains the shape of the pinch), the more dehydrated the horse.
This test does not work as reliably in foals. Their skin is loose, and even normal foal’s skin take longer to flatten out against their bodies after a pinch.
Standing on your horse's side, gently pinch a fold of skin between thumb and forefinger. Release it and observe how long it takes for the skin to flatten out and return to normal.
In normal healthy horses, the skin springs almost immediately back against the body. In horses suffering from mild, moderate, or severe dehydration, the skin remains tented or raised for a period, taking comparatively longer to return to normal.
Consider using this scale to evaluate your results:
Less than 1 second: Normal Hydration
1-2 seconds: Mild Dehydration
2-3 seconds: Moderate Dehydration
More than 3 seconds: Severe Dehydration
Tips for safety & Success
I prefer to perform this assessment on the point of the shoulder (not the neck), because it tends to have more consistently tense skin and provides me with more consistent information from horse to horse. Regardless, you should perform this skill on your horse in the same area every time.