Total injectable anesthesia of dogs and cats for remote location veterinary sterilization clinic.

BACKGROUND: Sterilization clinics often occur in remote places where anesthesia machines and compressed oxygen are unavailable. This study describes the use of total injectable anesthesia in dogs and cats presented for sterilization in a remote location. RESULTS: A total of 100 animals were sterilized; 26 female cats (CF), 22 male cats (CM), 28 female dogs (DF), and 24 male dogs (DM). CF were anesthetized with dexmedetomidine (20 mcg/kg), ketamine (8 mg/kg) and hydromorphone (0.1 mg/kg) IM. CM were anesthetized with dexmedetomidine (15 mcg/kg), ketamine (5 mg/kg) and hydromorphone (0.1 mg/kg) IM. Insufficient anesthesia in cats was treated with alfaxalone (1 mg/kg) IM. All cats were administered meloxicam at 0.3 mg/kg SQ. DF were anesthetized with dexmedetomidine (15 mcg/kg), ketamine (7-10 mg/kg) and hydromorphone (0.1 mg/kg) IM. DM were anesthetized with dexmedetomidine (15 mcg/kg), ketamine (5 mg/kg) and hydromorphone (0.1 mg/kg) IM. All dogs had IV catheter and endotracheal tube placed. If SpO2 < 91%, ventilation was assisted with an Ambu bag. Insufficient anesthesia in dogs was treated with alfaxalone (1 mg/kg) IV. All dogs were administered meloxicam at 0.2 mg/kg SQ. Following surgery, atipamezole (0.05-0.1 mg/kg) IM was administered to any patient that did not have voluntary movement. All patients survived and were discharged. Less than 25% of cats and male dogs required supplemental anesthesia. Fifty seven percent of female dogs required supplemental anesthesia. More than 89% of patients (in any group) required atipamezole administration. One cat recovered with agitation and hyperthermia (41.1C/ 106F). Some dogs required ventilatory assistance to remain normoxemic while anesthetized. CONCLUSION: Total injectable anesthesia can be accomplished for remote location sterilization clinics with minimal morbidity.

Repeated exposure of goldfish (Carassius auratus) to tricaine methanesulfonate (MS-222).

Goldfish that have been repeatedly exposed to tricaine methanesulfonate (MS-222) require greater concentration of the drug to attain equivalent planes of anesthesia, but the mechanism for this increased anesthetic need is unknown. Minimum anesthetic concentration (MAC) is a commonly used method with which to compare anesthetics. It was hypothesized that fish exposed to MS-222 daily would have an increased MAC. It was also hypothesized that fish exposed daily to MS-222 would develop histomorphologic changes to their gills to explain the increasing demand. Forty-nine Serasa comet goldfish were enrolled and were divided into three populations (n = 15, n = 15, and n = 19). In trial 1, using an up-down method, MAC was determined daily after 4 min of exposure to MS-222 for which the starting concentration was 160 mg/L. In trial 2, MAC was determined following 2 min of exposure to MS-222 for which the starting concentration was 260 mg/L. In trial 3, four naive fish were euthanatized and gills collected for histology and electron microscopy (EM). The remaining fish were exposed to MS-222 daily for 4 wk. Four fish were euthanatized and their gills submitted for similar examination at 2 wk and 4 wk. MAC for fish exposed to MS-222 for 4 min increased from 120 to 160 mg/L. The regression line had a slope of 1.51 +/- 0.26 (R2 = 0.65; P < 0.0001). MAC for fish exposed to MS-222 for 2 min increased from 210 pmm to 220 mg/L; the regression line had a slope of 0.52 +/- 0.38 (R2 = 0.12; P = 0.2). Histologic and EM examination of gills did not show morphologic changes indicative of a reaction to MS-222. Goldfish in this study had an increased requirement for MS-222 following daily exposure for 4 min but not following daily exposure for 2 min at a higher concentration. The cause of this increased anesthetic need is not related to morphologic changes to the gills.

Alfaxalone anesthesia in bullfrogs (Lithobates catesbeiana) by injection or immersion.

This project evaluated alfaxalone, a neurosteroid, as an anesthetic in bullfrogs. Eight adult bullfrogs (Lithobates catesbeiana), averaging 593 g (411-780 g) each, were used in a crossover design. Frogs were administered alfaxalone i.m. at 10, 12, 15, or 17.5 mg/kg with a 1-wk washout. Following injection, time to recumbency, first limb movement following induction, and recovery were recorded. Respiratory rate was recorded following injection and then every 15 min following induction. Heart rate was assessed via Doppler every 15 min following induction. At 20 and 40 min, a 25-ga needle was inserted in a thigh muscle to assess response to noxious stimuli. Frogs were also immersed in 2 g/L of alfaxalone for up to 30 min and similarly assessed. At dosages of 10, 12, 15, and 17.5 mg/kg, the median time to recumbency was 15.4, 12.6, 12.3, and 6.6 min, respectively. At dosages of 10, 12, 15, and 17.5 mg/kg, median time to first limb movement was 68.5, 77.5, 89.0, and 115 min, respectively. At dosages of 10, 12, 15, and 17.5 mg/kg, median time to recovery was 90, 68.5, 124.5, 115 min, respectively. Following induction, at 10, 12, 15, and 17.5 mg/kg, median heart rate was 42, 40, 40, and 42, respectively; and median respiratory rate was 44, 36, 29, and 35, respectively. Following administration of 10, 12, 15, and 17.5 mg/ kg, 8/8, 6/8, 7/8, and 8/8 frogs, respectively, responded to needle insertion. None of the frogs dosed by immersion became anesthetized. Intramuscular alfaxalone produced immobilization in frogs but did not provide sufficient anesthesia to prevent response to noxious stimuli. Alfaxalone immersion at 2 g/L for 30 min did not produce immobilization or anesthesia.