Dehydration is a major cause of death in young calves. Whether dehydration is because of diarrhea or decreased ability to nurse, the results are the same and fluid therapy is critical in saving dehydrated calves. Although you can pick the calf’s skin up over the back with your fingers and monitor how long it takes the skin to return to normal, according to Dr. Andrea Lear from the University of Tennessee (bovinevetonline.com) the best method of determining dehydration is eyeball recession. When dehydrated, the eyeball recedes back into the socket. The more it recedes, the more dehydrated the calf. It is recommended to check for eyeball recession at the inner corner of the eye, otherwise known as the medial canthus. To estimate dehydration measure the recession of the eyeball in millimeters and then multiply that number times two. If a calf has a 4 mm eyeball recession, the calf is about 8% dehydrated. Oral fluid therapy may be effective when a calf is 8% dehydrated or less. However, intravenous fluids will likely be necessary if a calf is more than 8% dehydrated.
Once a calf is dehydrated, they are unlikely to nurse and are usually in some stage of shock with low blood sugar. If oral fluids are possible, then oral electrolytes with high sodium in the fluids should be fed, using a feeding tube if needed, along with milk or milk replacer. It is not a good idea to stop the milk replacer or milk completely because the calf needs milk for energy. To estimate the amount of fluid needed to correct dehydration, multiply the weight of the calf in kilograms by the percent dehydration times 1000. Knowing how to check for dehydration in calves could save lives.