Perioperative inadvertent hypothermia (PIH) has been associated with adverse surgical outcomes including increased risk of surgical bleeding, surgical site infections, delayed recovery from anesthesia and prolonged hospital stays. Smaller, more juvenile animals such as are frequently found in a shelter spay/ neuter setting are suspected to be at increased risk. Incidence of PIH has been previously reported at 33% in dogs and 70% in cats undergoing surgery. A successful strategy or bundle of strategies for consistently minimizing the incidence of PIH has not been identified. The study has several goals. These are: 1) to evaluate the incidence and severity of PIH in a variety of settings including a spay/ neuter shelter setting; to determine the highest risk period during the anesthesia event for PIH and to evaluate associations between PIH and adverse patient outcomes at baseline 2) to identify patient risk factors for PIH that can be identified pre-operatively with the goal of alerting the clinician that a patient who is about to undergo anesthesia is at increased risk of PIH 3) to develop and implement a low cost thermal care bundle, and evaluate the effect of implementation on PIH incidence and patient outcomes. We anticipate that the information this study will provide will both enhance clinician understanding of the negative effects of falls in intra-operative body temperature on patient outcomes and provide a low cost solution to widespread issue. This will be of particular utility in the high risk populations seen in the shelter surgery setting.