Thierry Beths

Evaluation and optimisation of a target-controlled infusion system for administering propofol to dogs as part of a total intravenous anaesthetic technique during dental surgery

The performance of a modified target-controlled infusion system was investigated in 16 dogs undergoing routine dental work, by comparing the predicted concentrations of propofol in venous blood samples with direct measurements; the optimum targets for the induction and maintenance of anaesthesia were also identified. The performance of a target-controlled infusion system is considered clinically acceptable when the median prediction error, a measure of bias, is not greater than ±10 to 20 per cent, and the median absolute performance error, a measure of the accuracy, is not greater than 20 to 30 per cent. The results fell within these limits indicating that the system performed adequately. The optimal induction target was 3 μg/ml, and anaesthesia of adequate depth and satisfactory quality was achieved with maintenance targets of between 2.5 and 4.7 μg/ml propofol. The system was easy to use and the quality of anaesthesia was adequate for dental work.

Target-controlled infusion of propofol in dogs - evaluation of four targets for induction of anaesthesia

Four groups of 20 dogs were anaesthetised by means of target-controlled infusions of propofol designed to achieve 2·5 µg/ml, 3·0 µg/ml, 3·5 µg/ml or 4·0 µg/ml of propofol in blood. The dogs’ pulse rate and respiratory rate were recorded before premedication and induction, immediately after endotracheal intubation and three and five minutes later (times 0, 3 and 5, respectively), and their arterial blood pressure was recorded oscillometrically just before induction and at times 0, 3 and 5. The targets of 2·5, 3·0, 3·5 and 4·0 µg/ml resulted in the successful induction of anaesthesia in 13 (65 per cent), 16 (80 per cent), 20 (100 per cent) and 20 (100 per cent) of the dogs, respectively. The incidence of postinduction apnoea was 0 (0 per cent), one (5 per cent), two (10 per cent) and eight (40 per cent) at time 5 for groups 2·5, 3·0, 3·5 and 4·0 µg/ml, respectively, and its incidence at time 5 was significantly higher in the 4·0 µg/ml group (P<0·05) than in the other groups. In all the groups there was a significant (P<0·05) decrease in blood pressure between just before induction and the later measurements. Although there were no statistically significant differences between the groups in terms of inducing anaesthesia at a specific target, a target of 3·5 µg/ml appears to ensure a successful induction of anaesthesia without a significant increase in the incidence of apnoea.

A comparative study of xylazine-induced mechanical hypoalgesia in donkeys and horses.

OBJECTIVE To compare the effects of xylazine on mechanical nociceptive thresholds in donkeys and horses. STUDY DESIGN Randomized, controlled, crossover, Latin-square, operator-blinded design. ANIMALS Six 3.1 ± 0.89 year old standard donkeys weighing 145.0 ± 30.5 kg and six 9.6 ± 4.4 year old Thoroughbred horses weighing 456.0 ± 69.0 kg. METHODS Each animal received one of four doses of xylazine (0.5, 0.7, 0.9, and 1.1 mg kg(-1) ), or acepromazine (0.05 mg kg(-1) ) or saline solution (0.9%) intravenously and mechanical nociceptive thresholds were assessed over 90 minutes. The areas under the threshold change versus time curve values for 60 minutes (AUC(0-60) ) post-drug administration were used to compare the effect of treatment. A 1-week interval was allowed between successive trials on each animal. RESULTS All doses of xylazine, but not acepromazine or saline, increased mechanical thresholds for up to 60 minutes. Xylazine-induced hypoalgesia was dose-dependent and corresponding AUC(0-60) values for each treatment were not significantly different between donkeys and horses (p ≥ 0.0697). CONCLUSION The hypoalgesic effects of xylazine at four different doses were not different between donkeys and horses. CLINICAL RELEVANCE Xylazine induced a similar degree of mechanical hypoalgesia in donkeys and horses suggesting that similar doses are needed for both species with regard to analgesia.

A review of the pharmacology and clinical application of alfaxalone in cats

Alfaxalone-2-hydroxpropyl-β-cyclodextrin (alfaxalone-HPCD) was first marketed for veterinary use in Australia in 2001 and has since progressively became available throughout the world, including the USA, where in 2012 Food and Drug Administration (FDA) registration was granted. Despite the growing body of published works and increasing global availability of alfaxalone-HPCD, the accumulating evidence for its use in cats has not been thoroughly reviewed. The purpose of this review is: (1) to detail the pharmacokinetic properties of alfaxalone-HPCD in cats; (2) to assess the pharmacodynamic properties of alfaxalone-HPCD, including its cardiovascular, respiratory, central nervous system, neuromuscular, hepatic, renal, haematological, blood-biochemical, analgesic and endocrine effects; and (3) to consider the clinical application of alfaxalone-HPCD for sedation, induction and maintenance of anaesthesia in cats. Based on the published literature, alfaxalone-HPCD provides a good alternative to the existing intravenous anaesthetic options for healthy cats.

Comparison of perioperative analgesic efficacy between methadone and butorphanol in cats

OBJECTIVE To compare the perioperative analgesic effect between methadone and butorphanol in cats. DESIGN Randomized controlled clinical trial. ANIMALS 22 healthy female domestic cats. PROCEDURES Cats admitted for ovariohysterectomy were allocated to a butorphanol group (n = 10) or methadone group (12) and premedicated with butorphanol (0.4 mg/kg [0.18 mg/lb], SC) or methadone (0.6 mg/kg [0.27 mg/lb], SC), respectively, in combination with acepromazine (0.02 mg/kg [0.01 mg/lb], SC). Anesthesia was induced with propofol (IV) and maintained with isoflurane in oxygen. A multidimensional composite scale was used to conduct pain assessments prior to premedication and 5, 20, 60, 120, 180, 240, 300, and 360 minutes after extubation or until rescue analgesia was given. Groups were compared to evaluate isoflurane requirement, propofol requirement, pain scores, and requirement for rescue analgesia. RESULTS Propofol and isoflurane requirements and preoperative pain scores were not different between groups. During recovery, dysphoria prevented pain evaluation at 5 minutes. Pain scores at 20 minutes were significantly lower in the methadone group, and 6 of 10 cats in the butorphanol group received rescue analgesia, making subsequent pain score comparisons inapplicable. After 6 hours, only 3 of 12 cats in the methadone group had received rescue analgesia. CONCLUSIONS AND CLINICAL RELEVANCE In the present study, methadone appeared to be a better postoperative analgesic than butorphanol and provided effective analgesia for 6 hours following ovariohysterectomy in most cats.

Evaluation of the perioperative analgesic efficacy of buprenorphine, compared with butorphanol, in cats

OBJECTIVE To compare the analgesic effects of buprenorphine and butorphanol in domestic cats. DESIGN 2-phase positive-controlled randomized masked clinical trial. ANIMALS 39 healthy female cats (10 in phase 1 and 29 in phase 2). PROCEDURES Cats admitted for ovariohysterectomy received buprenorphine (4 in phase 1; 14 in phase 2) or butorphanol (6 in phase 1; 15 in phase 2). In phase 1, cats were premedicated with buprenorphine (0.02 mg/kg [0.009 mg/lb], IM) or butorphanol (0.4 mg/kg [0.18 mg/lb], IM), in combination with medetomidine. Anesthesia was induced with propofol (IV) and maintained with isoflurane in oxygen. After extubation, medetomidine was antagonized with atipamezole. A validated multidimensional composite scale was used to assess signs of pain after surgery starting 20 minutes after extubation and continuing for up to 360 minutes, and pain score comparisons were made between the 2 groups. Phase 2 proceeded similar to phase 1 with the following addition: during wound closure, cats from the butorphanol and buprenorphine groups received butorphanol (0.4 mg/kg, IM) or buprenorphine (0.02 mg/kg, IM), respectively. RESULTS Phase 1 of the study was stopped after 10 cats were ovariohysterectomized because 9 of 10 cats required rescue analgesia at the first evaluation. In phase 2, at the first pain evaluation, pain scores from the buprenorphine group were lower, and all cats from the butorphanol group required rescue analgesia. None of the cats from the buprenorphine group required rescue analgesia at any time. CONCLUSIONS AND CLINICAL RELEVANCE Buprenorphine (0.02 mg/kg, IM) given before surgery and during wound closure provided adequate analgesia for 6 hours following ovariohysterectomy in cats, whereas butorphanol did not.

Clinical evaluation of alfaxalone to induce and maintain anaesthesia in cats undergoing neutering procedures

This study looked at the use and efficacy of alfaxalone for total intravenous anaesthesia (TIVA) in cats. Following intramuscular medetomidine (20 μg/kg) and morphine (0.3 mg/kg) premedication, anaesthesia was induced and maintained with intravenous alfaxalone. Patients were breathing 100% oxygen. Heart rate (HR), respiratory rate (RR), end-tidal carbon dioxide, oxygen saturation of haemoglobin and indirect arterial blood pressure via Doppler (DAP) were recorded every 5 mins. Thirty-four cats (10 males and 24 females), between the age of 6 and 18 months, and weighing between 1.8 and 5.3 kg, and undergoing neutering procedures were included in this study. The results are presented as median (min, max) values. The time to first spontaneous movement (TS) was >30 mins in 19 cats, of which 12 received atipamezole for reversal of the effects of medetomidine. The TS was 53 (43, 130) mins in these 12 cats and 50 (40, 72) mins in the other seven cats. The body temperature in those 19 cats was significantly lower than the other cats (P = 0.05). The alfaxalone induction dose and maintenance infusion rate were1.7 (0.7, 3.0) mg/kg and 0.18 (0.06, 0.25) mg/kg/min, respectively. The HR, RR and DAP were 145 (68, 235) beats/min, 17 (5, 40) breaths/min and 110 (58, 210) mmHg, respectively. Apnoea was not observed in any cat. In conclusion, alfaxalone TIVA in combination with medetomidine and morphine premedication was effective in feral and domestic cats for the performance of neutering surgery; low body temperature might have resulted in longer recoveries in some cats.

Onset and quality of sedation after intramuscular administration of dexmedetomidine and hydromorphone in various muscle groups in dogs.

OBJECTIVE To compare onset time and quality of sedation achieved by IM injection of hydromorphone and dexmedetomidine into either the semimembranosus, cervical, gluteal, or lumbar muscle groups in dogs. DESIGN Prospective, randomized, crossover study. ANIMALS 7 dogs. PROCEDURES Each dog was assigned to receive each treatment in random order, and at least 1 week elapsed between treatments. Dogs were sedated with dexmedetomidine and hydromorphone combined and injected IM into the assigned muscle group. An observer unaware of group assignments assessed physiologic variables every 5 minutes for 30 minutes, and a videographic recording was obtained. Recordings were evaluated by 16 individuals who were unaware of group assignments; these reviewers assessed time to onset of sedation and assigned a sedation score to each dog every 5 minutes. RESULTS Resting pulse and respiratory rates did not differ among injection site groups. The semimembranosus site had a significantly higher sedation score than all other sites, and the cervical site had a significantly higher sedation score than the lumbar and gluteal sites. The semimembranosus and cervical sites had significantly shorter time to onset of sedation than did the gluteal and lumbar sites. CONCLUSIONS AND CLINICAL RELEVANCE When the combination of dexmedetomidine and hydromorphone was used to induce sedation in dogs, rapid and profound sedation was achieved with IM injection into the semimembranosus muscle.

Treatment of unresectable hepatocellular adenoma in dogs with transarterial iodized oil and chemotherapy with and without an embolic agent: A report of two cases

Transarterial iodized oil with chemotherapy was evaluated in two dogs with large, surgically unresectable hepatocellular adenoma. A single cycle of therapy was used in each dog. Chemoembolic mixtures varied: doxorubicin emulsified with iodized oil radiographic contrast (case 1), doxorubicin and mitomycin C emulsified with iodized oil radiographic contrast (case 2). In addition, dog 2 underwent arterial embolization with polyvinyl alcohol granules. Response was assessed by computed tomography at 1 and 3 months after treatment. Superselective catheterization of the hepatic arterial branch supplying the tumour was not achieved in either case. In the immediate post-operative period, both dogs developed mild clinical signs that may have been consistent with post-embolization syndrome, but neutropenia and reduced liver function were not observed. Tumour response was minimal: stable disease at 1 month and progressive disease at 3 months was observed in both cases.

Abdominal ultrasonography of the normal St. Kitts vervet monkey (Chlorocebus sabaeus)

Normal ultrasonography of non‐reproductive abdominal and male reproductive anatomy in the vervet monkey were prospectively assessed. This has not been previously reported.