In normal, healthy animals, fluid and electrolytes are balanced. In sick animals, this balance of fluid and electrolytes may be disrupted, making fluid therapy necessary. In healthy adult animals, approximately 60 percent of the body weight is water; in healthy neonates, approximately 80 percent of the body weight is water. Because neonates have a proportionally larger percent of body weight as water, dehydration is a significant problem in young animals. The basis for fluid therapy rests on the animal's hydration status. Hydration sta tus can be determined by assessing the patient's history, physical exam status(checking body weight, skin rate and quality, capillary refill time, moistness of mu cous membranes, and sunken eyes), and laboratory findings(such as TP(total protein) BUN(blood urea nitrogen), PCV(packed cell volume), and urine specific gravity). Table 19-1 provides guidelines for estimating level of dehydration.