During 1993, 66 small animal practices participated in a prospective study to evaluate the incidence and details of anesthetic-related morbidity and mortality. Considering a total of 8,087 dogs and 8,702 cats undergoing anesthesia, the incidences of complications were 2.1% and 1.3%, respectively. Death occurred in 0.11% and 0.1% of cases, respectively. Logistic regression models were developed and showed that a significant odds ratio (OR) of complications in dogs was associated with xylazine (OR, 91.5); heart rate monitoring (OR, 3.2); American Society of Anesthesiologists (ASA) 3, 4, or 5 classification (OR, 2.5); isoflurane (OR, 2.4); butorphanol (OR, 0.35); technician presence (OR, 0.26); acepromazine (OR, 0.24); ketamine (OR, 0.21); and mask induction (OR, 0.2). Complications in cats were associated with ASA 3, 4, or 5 classification (OR, 5.3); diazepam (OR, 4.1); intubation (OR, 1.7); butorphanol (OR, 0.45); and ketamine (OR, 0.17). Cardiac arrest in dogs was associated with xylazine (OR, 43.6) and ASA 3, 4, or 5 classification (OR, 7.1). Cardiac arrest in cats was associated with ASA 3, 4, or 5 classification (OR, 21.6) and technician presence (OR, 0.19). This paper reports the incidences of complications and cardiac arrest in small animal practice and identifies common complications and factors that may influence anesthetic morbidity and mortality. This information may be useful in comparing anesthetic management practices.