1- Evaluate the calf’s attitude and vigor. Dehydrated calves don’t stand up quickly and show a reduced interest in nursing.
2- Assess the suckle reflex by placing a finger in the calf’s mouth and see how it responds. The suckle reflex will be strong in well-hydrated calves but weak in calves experiencing dehydration.
3- Look at the eyeballs of the calf. As the calf becomes dehydrated the eyeballs pull inward and there is a gap between the eyelid surfaces and the eyeballs.
4- Check the calf’s skin tent by pulling up the skin and then releasing it. As dehydration progresses it will take more time for the skin to snap back into place (more than 2 seconds) With a severely dehydrated calf, that skin will take 10 seconds or more to return into place.
5- Examine the mucous membranes by checking the calf’s gums. They are moist in a normally hydrated calf and they will be sticky as the calf becomes dehydrated.
6- Capillary refill time: pressing the gum of calf by a finger and check for the color change of gum from pale to rose. In dehydrated calf the time is prolonged than 2 seconds