We conducted a 3-year study to document the physiological responses of red foxes (Vulpes vulpes) to foothold traps. Captive-raised foxes were caught and held for either 2 or 8 hours in No. 11/ padded-jawed, foothold traps or for 8 hours in No. 11/2 unpadded traps. Free-ranging foxes were also caught in the same trap types for variable periods. Nontrapped, free-ranging foxes were used as controls. Behavior of captive foxes was video recorded; heart rate and body temperature were monitored via radio telemetry; and endocrine, biochemical, hematological, and pathological samples were collected after the trapped fox was euthanized. Foxes caught in unpadded traps had higher physical injury scores to the trapped limbs than foxes caught in padded traps (P < 0.05). Heart rate and body temperature increased rapidly after foxes were caught, but returned to mean pretrapped levels after 80 minutes. Mean time spent physically resisting the trap in an 8-hour period was 17.8 ? 6.7 (SE) and 13.3 ? 0.3% for foxes caught in unpadded and padded traps, respectively (P = 0.33). Trapped foxes generally had higher levels of adrenocorticotropin, #-endorphin, and cortisol and lower levels of thyroxine and insulin compared to control foxes (P < 0.05). Foxes caught in unpadded traps had higher cortisol, but lower P-endorphin values than foxes caught in padded traps (P < 0.05). Trapped foxes also had higher levels of bilirubin, lactate dehydrogenase, alkaline phosphatase (ALP), and aspartate aminotransferase (AST) than control foxes (P < 0.05). Foxes caught in unpadded traps had higher values for ALP, AST, and gamma-glutamyl transpeptidase than foxes caught in padded traps (P < 0.05). Trapped foxes also had higher leukocyte counts than nontrapped foxes with a significant neutrophilia and leukopenia (P < 0.05). Trapped foxes had higher incidences of adrenal gland and kidney congestion as well as adrenal gland, lung, and heart hemorrhage relative to control foxes (P < 0.05). Most of the changes were consistent with the physical exertion of resisting the trap, and none appeared life-threatening. Overall, padded-jawed traps caused less trauma to red foxes than unpadded traps. J. WILDL. MANAGE. 54(1):147-160 Trapping with steel foothold traps provides significant income and recreational value for about 600,000 North Americans (Todd and Boggess 1987). Foothold traps are also the primary means used by the U. S. Fish and Wildlife Service (USFWS) to control coyotes (Canis latrans) and wolves (Canis lupus) that attack livestock (Olsen et al. 1986). For almost a century, however, antitrapping groups have sought to ban foothold traps in the United States and Canada. Over 450 antitrapping bills have been introduced in state legislatures and the Federal Congress since 1900 (Gentile 1987). In the face of escalating antitrapping initiatives, the fur industry has developed trapping systems that reduce injury to the furbearer. Recent research has concentrated on padded-jawed traps (Tullar 1984; Linhart et al. 1986; Olsen et al. 1986, 1988; Linscombe and Wright 1988). Such traps, equipped with padded jaws, center swivels, reduced spring tension, and shock-absorbing coil springs in the chain, significantly reduced leg injuries in red foxes (Tullar 1984, Olsen et al. 1988). Whereas previous research investigated effects on the trapped limb, there are also surprise, fear, pain, and physical exertion in an animal's reaction to being trapped. Any of these could result in detectable tissue lesions depending on the degree and duration of response. Being trapped can be considered a stressor which activates predictable physiological responses (Moberg 1985). It is thus important to look at indices of an animal's internal milieu to better define its total response to being trapped. To understand physiological responses to restraint and to assess differences in these responses relative to different traps, we conducted research for 3 years on red foxes. Our objectives were to examine the behavioral, physiological, endocrine, biochemical, and pathological responses of both free-ranging and captive red foxes caught by unpadded and padded-jawed foothold traps as well as to compare such responses with those of untrapped foxes. This study was financed by the Fur Institute of Canada. We are indebted to A. B. Sargeant, J. M. Callow, and staff, Northern Prairie Wild-