Clinical use of dexmedetomidine as premedicant in cats undergoing propofol-sevoflurane anaesthesia

The purpose of this report was to evaluate the cardiorespiratory effects and efficacy of dexmedetomidine as a premedicant agent in cats undergoing ovariohysterectomy anaesthetized with propofol-sevoflurane. Cats were randomly divided into two groups of eight animals each. Dexmedetomidine (0.01 mg/kg) or 0.9% saline was administered intravenously (D and S, respectively). After 5 min, propofol was administered intravenously and anaesthesia was maintained with sevoflurane. Heart and respiratory rates, arterial blood pressure, oxygen saturation, rectal temperature and the amount of propofol needed for induction were measured. Premedication with dexmedetomidine reduced the requirement of propofol (6.7+/-3.8 mg/kg), but induced bradycardia, compared with the administration of saline (15.1+/-5.1 mg/kg). Recovery quality was significantly better in D but no significant difference in time to return of swallowing reflex was observed between groups (D=2.5+/-0.5 min; S=3.2+/-1.8 min). In conclusion, dexmedetomidine is a safe and effective agent for premedication in cats undergoing propofol-sevoflurane anaesthesia with minimal adverse effects.     

Clinical evaluation of Alfaxan-CD® as an intravenous anaesthetic in young cats

Objective   To describe and evaluate the use of Alfaxan-CD ® as an intravenous anaesthetic in young cats.
Design   Thirty-five Domestic Short-hair cats aged from 3 to 12 months were admitted into the University Veterinary Teaching Hospital-Sydney for elective surgery. Anaesthesia was induced with Alfaxan-CD® and maintained with isoflurane: 22 cats received no premedication and 13 cats received acepromazine (0.03 mg/kg) and butorphanol (0.3 mg/kg) subcutaneously 30 min prior to induction.
Qualitative and quantitative data for induction and recovery were recorded. Physiological parameters were recorded at 0, 2 and 5 min post induction, and every 5 min thereafter until the end of the procedure.
Results   Intravenous injection of Alfaxan-CD® resulted in rapid induction of anaesthesia with a mean time to intubation of 122 s. The mean dose of Alfaxan-CD® used was 4.2 mg/kg in unpremedicated cats and 2.7 mg/kg in premedicated cats. All cats maintained a heart rate above 95 beats/min. No cat developed hypoxaemia. Hypercapnoea was detected in 4 cats and hypotension was observed in 18 cats. Time to extubation ranged from 1 to 9 min. The mean time to sternal recumbency for premedicated cats was 11 min; 77% of premedicated cats and 23% of unpremedicated cats had a recovery score of 1 or 2.
Conclusion   Alfaxan-CD® is an effective anaesthetic agent in young healthy cats, providing a smooth induction and rapid recovery. Cats that were premedicated with acepromazine and butorphanol prior to induction with Alfaxan-CD® had better recovery scores than those that were not premedicated.     

Clinical evaluation of propofol as an intravenous anaesthetic agent in cats and dogs

The clinical efficacy and safety of an emulsion containing 10 mg/ml of the intravenous anaesthetic propofol were evaluated in cats and dogs by veterinary surgeons in eight practices in the United Kingdom. A total of 290 dogs and 207 cats were anaesthetised with propofol either as a single injection for procedures of short duration, or as an induction agent with maintenance provided by further incremental injections or as an induction agent with maintenance by gaseous agents. The mean induction doses of propofol for unpremedicated dogs and cats were respectively 6.55 mg/kg and 8.03 mg/kg. The mean induction doses after premedication with a tranquilliser were 4.5 mg/kg and 5.97 mg/kg for dogs and cats, respectively. Mean recovery times ranged, depending on the method of anaesthesia, from 23 to 40 minutes in dogs and from 27 to 38 minutes in cats; recovery was defined as the time at which the animals were alert and able to stand. Adverse side effects were infrequent, apnoea during induction being the commonest. Acepromazine and atropine were most often used as premedicants although in a few cases diazepam, xylazine and other agents were employed. No clinical incompatibility was observed between propofol and any of the other agents administered during the study. The rapid and usually excitement-free recovery of the animals was a valuable feature of anaesthesia with propofol.     

A steroid anaesthetic for cats

Extract

Hans Selye, at McGill University, Montreal, was the first to demonstrate the anaesthetic activity of steroids — in 1941. While investigating the effects of overdosage of several steroid hormones in rats, he discovered that large amounts injected intraperitoneally induced anaesthesia. His observations have led to the development, some 30 years later, of a new steroid anaesthetic. The preparation was investigated under the provisional name CT 1341, and clinical trials in animals and man have shown that it possesses many useful properties. This preparation is now available under the trade name “Saffan” (Glaxo).     

Propofol as an intravenous anaesthetic agent in dogs

Studies in dogs with an emulsion formulation of the intravenous anaesthetic, propofol, showed that induction of anaesthesia was smooth and it was possible to maintain anaesthesia by intermittent injection. The mean dose for induction of anaesthesia in unpremedicated dogs was 5.95 mg/kg body-weight. When no premedication was administered anaesthesia was maintained by a total dose of approximately 0.806 mg/kg/minute. Premedication with between 0.02 and 0.04 mg/kg of acepromazine reduced the mean induction dose by about 30 per cent and the maintenance dose by more than 50 per cent. In 68 unpremedicated dogs given one dose, recovery was complete in a mean time of 18 minutes and after maintenance of anaesthesia by intermittent injection in 65 dogs the mean recovery time was 22 minutes from administration of the last dose. Premedication with acepromazine did not produce statistically significant increases in these recovery times. The quiet, rapid and complete recovery proved to be most valuable in cases where the animal had to be returned to the owners' care with the minimum of delay.     

Determination of the sevoflurane sparing effect of methadone in cats

ObjectiveTo determine the magnitude and duration of sevoflurane minimum alveolar concentration (MAC) reduction following a single intravenous (IV) dose of methadone in cats.Study designProspective experimental study.AnimalsEight (four females and four males) healthy mixed-breed adult (1–2 years) cats weighing 5.82 ± 0.42 kg.MethodsAnesthesia was induced and maintained with sevoflurane. Intravenous catheters facilitated administration of methadone and lactated Ringer’s solution. After baseline MAC determination in triplicate using a tail clamp technique, 0.3 mg kg^?1 of methadone was administered IV. End-tidal sevoflurane concentration (e′SEVO) was reduced and MAC was redetermined. In an effort to determine the duration of MAC reduction, measurements were repeated in a stepwise manner until MAC values returned to baseline. After the last stimulation, the e′SEVO was increased to 1.2 individual MAC for 15 minutes, then sevoflurane was discontinued and cats were allowed to recover from anesthesia.ResultsBaseline sevoflurane MAC was 3.18 ± 0.06%. When compared with baseline the sevoflurane MAC after methadone administration was significantly reduced by 25, 15 and 7% at 26, 76 and 122 minutes, respectively. The final MAC value (3.09 ± 0.07%) determined 156 minutes after methadone administration was not significantly different from baseline.Conclusions and clinical relevanceIntravenous methadone (0.3 mg kg^?1) significantly decreased MAC of sevoflurane in cats but the effect was short-lived.     

Risk of anaesthetic mortality in dogs and cats: an observational cohort study of 3546 cases

Objective To evaluate the anaesthetic death risk for dogs and cats in a French private practice. Study design Observational cohort study. Animal population All small animals anesthetized at the Centre Hospitalier Vétérinaire des Cordeliers between April 15th, 2008 and April 15th, 2010. Methods General anaesthesia was defined as a drug‐induced unconsciousness characterised by a controlled and reversible depression of the central nervous system and analgesia, sufficient to allow endotracheal intubation. Patient outcome (alive or dead) was assessed at the end of anaesthesia defined as the meeting point of the return of consciousness, rectal temperature >36 °C and ability to maintain sternal recumbency. Death occurring during anaesthesia was recorded. Relationship between anaesthetic death and ASA status, species, age, nature of the procedure, anaesthetic protocol and occurrence of epidural administration of a combination of morphine and bupivacaine were analysed. Results During the study period 3546 animals underwent general anaesthesia. The overall death rate in the present study was 1.35% (48 in 3546, 95% CI 0.96–1.75). The death rate of healthy animals (ASA 1 and 2) was 0.12% (3 in 2602 95% CI 0.02–0.34). For sick animals (ASA status 3 and over), the overall death rate was 4.77% (45 in 944 95% CI 3.36–6.18). The death rates in the ASA 3, 4 and 5 categories were 2.90%, 7.58% and 17.33%, respectively. The main factor associated with increased odds of anaesthetic death in ASA categories 3 and over was poor health status (ASA physical status classification). The nature of the procedure the patient underwent and epidural administration of a combination of morphine and bupivacaine were not correlated with the occurrence of death during anaesthesia. Neither species nor age effects were detected. Conclusion and clinical relevance Specific factors were associated with increased odds of anaesthetic death, especially poor health status. Efforts must be directed towards thorough preoperative patient evaluation and improvement of clinical conditions if possible. Identification of risk factors before anaesthesia should lead to increased surveillance by trained staff. This could result in better outcomes.     

Medetomidine as a premedicant in dogs and its reversal by atipamezole

Medetomidine (10, 20, 40 μg/kg) was used as a premedicant before thiopentone, halothane and nitrous oxide anaesthesia in 60 dogs undergoing a variety of elective surgical and diagnostic procedures at the University of Liverpool Small Animal Hospital. The efficacy of the sedation produced by the three dose groups was evaluated using a sedation scoring system which is presented. Induction of anaesthesia was accomplished using 1–25 per cent thiopentone sodium administered slowly to effect. The mean dose of thiopentone required for intubation following 10 μ-g/kg medetomidine (group 1) was 6–9 mg/kg (SD ± 2–3 mg/kg), following 20 μ-g/kg medetomidine (group 2) was 4–5 mg/kg (SD ± 1–6 mg/kg) and following 40 μg/kg (group 3) was 2–4 mg/kg (SD ± 2–5 mg/kg). Induction of anaesthesia was generally smooth and significant apnoea (greater than 45 seconds) was not noted. Anaesthesia was maintained in all cases using halothane vapourised in a one part oxygen to two parts nitrous oxide mixture, delivered to the patient via a suitable non-breathing circuit (Magill, Bain or T Piece). At the conclusion of the procedure, atipamezole (50, 100, 200 μg/kg) was administered intramuscularly to half of the dogs in each group (10 dogs). Dogs receiving atipamezole recovered rapidly and smoothly to sternal recumbency, group 1 taking 8-5 minutes (SD ± 2–7 minutes), group 2 taking 11-8 minutes (SD ± 3–6 minutes), and group 3 taking 12-6 minutes (sd ± 4–5 minutes). When atipamezole was not administered a dose dependent increase in recumbency time occurred.     

Clinical evaluation in cats of a new anaesthetic, GT 1341

The results of a co-ordinated multicentred clinical evaluation of a new steroid anaesthetic for cats, CT 1341, are presented. Forty-six practising veterinary surgeons were involved. Administration by the intravenous, intramuscular and combined intramuscular-intravenous routes was tried. It was concluded that CT 1341 is a safe anaesthetic in cat practice when given intravenously. When employed by the intramuscular route it induced deep sedation and in some cases anaesthesia, depending on the dosage used.     

Use of ketoprofen as an antipyretic in cats.

The antipyretic effectiveness of Ketoprofen, a non-steroidal anti-inflammatory drug, was investigated in pyretic cats with a variety of bacterial and viral infections. Cats were randomly assigned to receive either a broad-spectrum antibiotic or a broad-spectrum antibiotic plus ketoprofen. Body temperature was monitored 3 times daily, and attitude and appetite were evaluated once daily. The treatment groups were compared with respect to mean body temperatures, using a one-way analysis of variance. Mean temperatures were significantly different (P < 0.05) during the 4 and 8 h post-treatment observations, with a reduction to normal temperatures in the ketoprofen group compared with no change in the group treated with antibiotics alone. The antipyretic effect of ketoprofen was rapid and persisted for at least 8 h, but for less than 24 h. The overall recovery period from pyrexia, depression, and inappetance was also shorter in cats treated with antibiotics and ketoprofen (3 d) than in cats treated only with antibiotics (5 d). Ketoprofen was a useful adjunct in the treatment of pyretic cats.     

Pentobarbitone as an anaesthetic agent in the Adelie penguin Pygoscelis adeliae

Thirty-two Adelie penguins were injected with sodium pentobarbitone (May & Baker). In twenty-two the intraperitoneal (IP) route alone was used and in ten both the IP and intravenous (IV) routes. The average time until the onset of surgical anaesthesia was 130 min (45-220). Four penguins died whilst under anaesthetic for unknown reasons and one from blood loss, the remaining twenty-seven survived for periods up to 13 hours and were electively killed. It is suggested that the variation in the anaesthetic induction period is due to the variation in the body fat content. One bird was left to recover and was immobile for 78 hours. In the penguin, barbiturates are presumably metabolized very slowly.
Sodium pentobarbitone (50 mg kg^-1) is recommended as an anaesthetic agent for deep surgical anaesthesia, provided that it is a nonsurvival procedure, and rapid induction is not necessary.