Abstract

The pudu (Pudu pudu) is a native species of southern Chile. The pudu is listed as vulnerable in the Red Book of terrestrial vertebrates of Chile. Since this species is highly susceptible to stress it is important to have a safe anesthesia protocol when immobilization is required for managing medical and/or management problems and other investigations. Combinations of ketamine, medetomidine and butorphanol have been reported to be useful for routine sedation of small hoofed species.¹ Ten captive pudu were immobilized with ketamine-medetomidine-butorphanol (KMB) in December of 2000 and January of 2001 at the National Zoo in Santiago, Chile. All measurements were recorded and are represented in this report as the average ± one standard deviation for each parameter reported. The body weight (BW) in kg of the study population was measured 1 week prior to conducting the series of anesthetic procedures reported in this study (Table 1). Each of the animals in the study group were hand injected intramuscularly with a combination of KMB mixed into a single syringe. Each animal was either caught in a hoop net or manually restrained. Once restrained, the KMB injection was given quickly, and the animal was released to reduce stress during induction. Two slightly different protocols were evaluated (groups 1 and 2). Results of KMB effects for each group are summarized in Table 1.

Table 1. Average ± one standard deviation for each of the parameters recorded for KMB-treated animals in group 1 and 2

Groups 1 and 2 consisted of five animals each. Each group one animal received KMB at a dose rate of 5 mg/kg of ketamine HCl, 0.07 mg/kg of medetomidine HCl, and 0.3 mg/kg of butorphanol tartrate. Each group 2 received KMB at a dose rate of 2.5 mg/kg ketamine HCl, 0.07 mg/kg of medetomidine HCl, and 0.3 mg/kg of butorphanol tartrate. The induction time (IT) for both groups 1 and 2 was defined as the time post-KMB injection (PI) to the onset of recumbency sufficient to facilitate manual restraint without significant struggling or escape attempts. Once thus sedated, each animal was monitored for 40 minutes. In all cases, at the point where animals were first restrained the following parameters were measured; temperature (T) was measured in degrees Celsius using a rectal thermometer, heart rate (HR, beats/minute), respiratory rate (RR, respirations/minute), and relative hemoglobin saturation (SpO₂) was measured by placing an oximeter probe on the tongue. At 40 minutes after KMB injection each animal was given atipamezole at 0.35 mg/kg and naloxone at 0.1 mg/kg were administered to reverse the effects of sedation. In all cases 50% of the total atipamezole and naloxone doses were given intramuscularly and remaining total dose of each antagonist was then given. Recovery time (RT) for groups 1 and 2 was defined as the time in minutes from administration of antagonists (PA) to standing posture.

The quality of immobilization was good with both protocols, with adequate muscle relaxation and analgesia in both groups to conduct routine medical examination routines (exam, blood collection, administration of minor noxious stimuli). Significant differences (p<0.05) were seen between the protocols for body temperature and heart rate. Pulse oximetry values were strongly suggestive of hypoxemia, which can be addressed in most species by administration of 100% oxygen at 2–4 l/min through a soft rubber cannula inserted into one nostril. Induction time was not affected by ketamine dose, but mild residual ataxia was seen after reversal in group 1, suggesting that the higher dose of ketamine was responsible for the residual ataxia observed. These data demonstrate that KMB produced adequate chemical immobilization in pudu to safely accomplish routine medical/management procedures in the captive pudu examined. Recovery after administration of atipamezole and naloxone was rapid and smooth. Post-recovery sedation was not observed in any of the animals in groups 1 or 2.

Literature Cited

1.  Morris, P.J. 2001. Chemical immobilization of felids, ursids and small ungulates. Vet Clin. N. Am., Exotic Practice 4(1):267–298.