Glucose containing fluids are administered when anesthesia is to occur for one or more hours. Puppies and kittens cannot concentrate urine as well as adults until they are 6 to 8 weeks old. This is one reason they have greater fluid requirements relative to their body mass in comparison to adult animals. In addition, puppies and kittens lose more water by insensible mechanisms and are more sensitive to water restriction, i.e., they dehydrate more quickly. Mean arterial blood pressure in the pediatric patient increases by six weeks of age but is not up to adult ranges for several months.
Tidal volume is similar to an adult by four weeks of age.
Anesthetic depression and hypoventilation may have a more pronounced affect in a pediatric patient. Induction of anesthesia and recovery from anesthesia by inhaled gases is more rapid because of high alveolar ventilation in pediatric animals. Very young patients also have very a compliant thorax that may collapse during inspiration. This makes it difficult for the neonate to overcome hypoventilation on its own and careful ventilation assistance should be provided by gentle intermittent positive pressure ventilation. Puppies and kittens over 4 weeks old can spontaneously ventilate, but an occasional assisted breath can aid prevention of atelectasis just as in the adult patient. .