Physiological responses of fishers to immobilization with ketamine, ketamine-xylazine, or Telazol®

We immobilized wild-caught fishers (Martes pennanti) to evaluate health and identify and treat pre-existing injuries or diseases prior to their reintroduction into Pennsylvania. We determined the safety and effectiveness of ketamine (KET), ketamine and xylazine (KET-XYL), and Telazol® (TEL) with anesthesia intervals (induction time, down time, alert time, and recovery time) and physiological parameters (rectal temperature and respiration rate monitored at 4-min intervals). We sufficiently immobilized 90 of 106 fishers (85%) for examination with 100 mg KET (n=47), 100 mg KET and 10 mg XYL (n=14), or 30 mg TEL (n=29). Differences occurred among drugs for down time (P=0.007), alert time (P=0.006), and recovery time (P≤0.001). Differences in mean body temperatures occurred among drug groups at 8 minutes (P=0.009) and 20 minutes post-injection (P=0.020). Differences in mean respiration rates occurred among drug groups at 4 minutes (P=0.013), 8 minutes (P≤0.001), 12 minutes (P≤0.001), and 16 minutes (P≤0.001), but not at 20 minutes (P=0.193). Ketamine immobilization of fishers was most appropriate for brief examinations (recovery time x±SD: 61.6±26.44 min), a valuable characteristic for field examinations. Ketamine-xylazine immobilization provided relatively short recoveries (128.9±56.67 min) and is considered a safe immobilant in a variety of situations. Long recoveries (238.6±89.25 min) may restrict Telazol to use in captivity or prior to extended transport. However, all 3 immobilants were safe and effective to facilitate physical examinations of fishers.