Katsuaki Takase

Cardiopulmonary effects of sevoflurane in cats: comparison with isoflurane, halothane, and enflurane

The cardiopulmonary effects of sevoflurane (mean, 2.6, 3.8-3.9 and 5.2 per cent) were compared with those of halothane (1.2, 1.8 and 2.4 per cent), enflurane (2.4, 3.6 and 4.8 per cent) and isoflurane (1.6, 2.4 and 3.2-3.3 per cent) at end-tidal concentrations equivalent to 1, 1.5 and 2 minimal alveolar concentrations (MACs) during spontaneous or controlled ventilation (SV or CV) in 57 cats. Cats were assigned to four groups of nine animals each in SV trial and four groups of five or six animals each in CV trial. During SV, respiration rate was decreased by sevoflurane and isoflurane at 2 MAC and by enflurane at each MAC multiple when compared with control values, whereas halothane increased respiration rate at 2 MAC. The degree of hypercapnia and acidosis induced by sevoflurane was not different from that induced by isoflurane and was less than that induced by halothane at 1 to 1.5 MAC or enflurane at 2 MAC. During SV and CV, four anaesthetics decreased heart rate at 2 MAC when compared with control values, but there was no significant difference between anaesthetics. Sevoflurane, like halothane and isoflurane, induced hypotension at 2 MAC when compared with 1 MAC.

Usefulness of systemic inflammatory response syndrome criteria as an index for prognosis judgement

S. Okano, DVM, PhD, M. Yoshida, DVM, U. Fukushima, DVM, PhD, S. Higuchi, DVM, PhD, Department of Small Animal Medicine, K. Takase, DVM, PhD, Department of Veterinary Surgery, School of Veterinary Medicine and Animal Sciences, Kitasato University, Towada, Aomori 034-8628, Japan M. Hagio, DVM, PhD, Department of Veterinary Surgery, Faculty of Agriculture, Miyazaki University, Miyazaki 889-2192, Japan S. OKANO, M. YOSHIDA, U. FUKUSHIMA, S. HIGUCHI, K. TAKASE, M. HAGIO

Ventricular arrhythmogenic dose of adrenaline during sevoflurane, isoflurane, and halothane anaesthesia either with or without ketamine or thiopentone in cats

The doses of adrenaline required to induce ventricular arrhythmia during sevoflurane, isoflurane and halothane anaesthesia, either with or without infusions of ketamine (76 micrograms kg-1 min-1) or thiopentone (0.5 mg kg-1 min-1), were determined in cats. Groups of six to eight cats were maintained at end-tidal concentrations equivalent to 1.25 times the minimal alveolar concentration of each anaesthetic. The mean dose of adrenaline required to induce arrhythmia during sevoflurane anaesthesia (19.0 micrograms kg-1) was approximately 11 times higher than that required during halothane anaesthesia (1.66 micrograms kg-1) and the same as that required during isoflurane anaesthesia (19.0 micrograms kg-1). Ketamine tended to decrease the requirement of adrenaline during halothane anaesthesia, but not significantly, and did not change the requirement during isoflurane or sevoflurane anaesthesia. Thiopentone did not change the requirement for adrenaline during halothane, isoflurane or sevoflurane anaesthesia. It was concluded that either with or without ketamine or thiopentone, the effect of sevoflurane on the sensitisation of the feline myocardium to the arrhythmogenic effects of adrenaline was significantly less than that of halothane and not different from that of isoflurane.

Evaluation of immunological status in tumor-bearing dogs.

The purpose of this study was to evaluate immunological status in dogs with cancers at different stages, in comparison with normal dogs. The population of canine peripheral blood lymphocytes (cPBL), lymphocyte phenotypes, interleukin (IL)-6 activity and alpha 1-acid glycoprotein (alpha(1)-AG) level were analyzed. The tumor-bearing dogs had higher numbers of leukocytes than normal dogs, the count being higher in dogs with more advanced tumors. In the tumor-bearing dogs, differential leukocyte counts revealed higher percentages of inflammatory cells such as neutrophils, acidophils and monocytes, and lower numbers of CD4(+)T cells, than in normal dogs, the lymphocyte counts becoming much lower with tumor progression. In the tumor-bearing dogs, the CD8(+)T cell count at the early tumor stage was similar to that in normal dogs, but decreased with tumor progression, possibly reflecting the development of humoral immunity (Th2). Plasma IL-6 and TGF-beta activities were high in the tumor-bearing dogs. The plasma alpha(1)-AG concentration was also significantly high in the tumor-bearing dogs. Our findings suggest that assay of IL-6, TGF-beta and alpha(1)-AG may be very useful for prognostication in dogs with cancer, and that anti-tumor immunity is potently suppressed in such dogs.

Clinical, cardiopulmonary, hematological and serum biochemical effects of sevoflurane and isoflurane anesthesia in oxygen under spontaneous breathing in sheep.

Effects of sevoflurane and isoflurane anesthesia in oxygen on clinical, cardiopulmonary, hematological, and serum biochemical findings were compared in sheep breathing spontaneously undergoing minor surgical operations during short-term (60-80min) or long-term (3-4h) anesthesia. All sheep were premedicated with atropine sulfate (0.1mg/kg) intramuscularly, and 10min later, induced to anesthesia by intravenous infusion of sodium thiopental (mean 14.1+/-3.4 S.D. mg/kg). After intubation, they were anesthetized with either isoflurane or sevoflurane in oxygen at a total gas flow rate of 1.5l/min. The results revealed that recovery time with sevoflurane was more rapid than with isoflurane. Respiration rates, tidal volume, minute ventilation and heart rates during sevoflurane anesthesia were similar to those during isoflurane anesthesia. The degree of respiratory acidosis during sevoflurane anesthesia was also similar to that during isoflurane anesthesia. There were no significant differences between sevoflurane and isoflurane anesthesia in hematological and serum biochemical values.

Serum α-1-acid glycoprotein concentration in clinically healthy puppies and adult dogs and in dogs with various diseases

BACKGROUND alpha-1-acid glycoprotein (AGP) is an acute-phase protein and a serum marker of inflammation and neoplasia in humans. AGP concentrations in diseased dogs and the potential effects of age, breed, and sex have not been elucidated. OBJECTIVE The purpose of this study was to examine differences in AGP concentration based on age, sex, and breed in a large population of clinically healthy dogs and to compare AGP concentrations in dogs with various diseases. METHODS Serum was obtained from clinically healthy puppies (n=74) and adults (n=172) of both sexes, and included mongrels (n=205) and Beagles (n=41). Serum also was obtained from 192 dogs with various diseases, including 8 with pyometra that were sampled before, and 1, 2, 3, and 10 days after surgery. AGP concentration was measured by single radial immunodiffusion. Statistical comparisons were made among age, sex, breed, and disease groups. RESULTS Serum AGP in healthy adult mongrels was 364+/-106 mg/L (reference interval, 152-576 mg/L). AGP was lowest in newborns (n=11, 122+/-54 mg/L) and gradually increased to adult levels by 3 months of age. Median AGP concentration was highest in dogs with parvovirus (n=17, 2100 mg/L), distemper (n=7, 1250 mg/L), and pyometra (n=18, 2480 mg/L) and was also significantly higher in dogs with acute filariasis, renal failure, urolithiasis, pancreatitis, hepatitis, trauma, hyperadrenocorticism, and immune-mediated hemolytic anemia. Dogs with acute filariasis and acute hepatopathy had significantly higher AGP concentrations than dogs with chronic filariasis and chronic hepatopathy. Serum AGP concentration decreased gradually following surgery for pyometra but remained increased after 10 days (896+/-175 mg/L). CONCLUSIONS Because of significantly lower AGP in puppies, the age of dogs should be considered when using AGP as a marker of disease. Serum AGP may be a useful marker of inflammatory disease in dogs and may help differentiate acute and chronic stages of disease.

Antagonism of the emetic action of xylazine by α-adrenoceptor blocking agents

The intramuscular injection of xylazine (2 mg/kg) evoked vomiting in 81% of the dogs studied. Adrenoceptor antagonists showing α2-blocking activity, yohimbine, tolazoline and phentolamine, antagonized the xylazine-induced vomiting in a dose-dependent manner. Of these antagonists, yohimbine was the most effective, since the maximal antagonistic effect was seen at 0.5 mg/kg yohimbine, a dose at which the other drugs had less or no effect. The adrenoceptor antagonists showing α1-blocking activity, prazosin and phenoxybenzamine, at the doses studied did not prevent the emesis induced by xylazine. A β-adrenoceptor antagonists, propranolol, was ineffective in reducing xylazine-induced vomiting. The dopamine receptor antagonists, metoclopramide and domperidone, did not prevent xylazine-induced vomiting nor did yohimbine antagonize apomorphine-induced vomiting. The xylazine-induced vomiting was not prevented by atropine, naloxone or hexamethonium. These results indicate that the xylazine-induced vomiting is mediated by α2-adrenoceptors and does not appear to involve β-adrenoceptors, cholinoceptors, dopamine or opiate receptors in the emetic pathway.

Electroencephalogram under xylazine-induced sedation in calves.

Xylazine was administered intravenously at a dosage level of 0.2 mg/kg to 7 calves and changes in EEG were examined. The EEG was recorded using needle electrodes by monopolar recording in the bilateral frontal and occipital areas. In the EEG tracing before xylazine administration, low-amplitude (about 10μV) β waves were predominant and 10 to 20 μV a waves and 20 to 30 μV θ waves were also observed. Furthermore, part of β waves were superimposed on θ waves. Slow waves with a frequency of 3 Hz or less (δ waves) appeared 1 to 2 min after xylazine administration and persisted for about 20 min. The amplitude of δ waves often exceeded beyond 100μV, and those in the occipital area were higher than those in the frontal area. The incidence and amplitude ofδ waves were decreased and the incidences of a and β waves were increased 30 min or more after xylazine administration. The EEG findings obtained 90 min after xylazine administration were almost the same as before the administration. When photic stimulation was given at 10 and 60 min after xylazine administration, photic driving which was predominant in the occipital area was observed in all animals.

The effect of yohimbine on xylazine-induced sedation and hyperglycemia in cattle.

キシラジンはα2アドレナリン作動薬と考えられている。今回, 牛のキシラジン投与でみられる鎮静, 過血糖に対し, α2受容体遮断薬のヨヒンビンが及ぼす影響について検討した。供試牛は延べ17頭使用し, キシラジン0.1mg/kg投与例 (I群) , 同量のキシラジン投与30分後ヨヒンビン0.5mg/kg投与例 (II群) , 同じく10分後ヨヒンビン投与例 (III群) , ヨヒンビン0.5mg/kg前処置後キシラジン0.1mg/kg投与例 (IV群) , 同じくキシラジン0.05mg/kg投与例 (V群) について比較検討した結果, つぎのような成績が得られた。1.キシラジンの鎮静に対し, ヨヒンビンの投与時間に関係なくいずれも拮抗作用は認められず, 他の動物での成績とまったく異なる結果を示した。2.キシラジンによる過血糖, 低インスリン血症 (1群) は, ヨヒンビン前処置 (IV群) によって著しく抑制され, V群ではほぼ完全に抑えられた。以上の成績により, 牛においてはキシラジンの拮抗薬としては, ヨヒンビン単独では効果のないことが明らかとなった。また, キシラジンの過血糖はα2アドレナリン受容体を介するものと考えられた。