Intranasal oxygen reverses hypoxaemia in immobilised free-ranging capybaras (Hydrochoerus hydrochaeris)

Capybara (Hydrochoerus hydrochaeris) is the main host of tick-borne pathogens causing Brazilian spotted fever; therefore, controlling its population is essential, and this may require chemical restraint. We assessed the impact of chemical restraint protocols on the partial pressure of arterial oxygen (PaO2) and other blood variables in 36 capybaras and the effect of different flows of nasal oxygen (O2) supplementation. The capybaras were hand-injected with dexmedetomidine (5 μg/kg) and midazolam (0.1 mg/kg) and butorphanol (0.2 mg/kg) (DMB, n = 18) or methadone (0.1 mg/kg) (DMM, n = 18). One-third of the animals were maintained in ambient air throughout the procedure, and one-third were administered intranasal 2 L/min O2 after 30 min whereas the other third were administered 5 L/min O2. Arterial blood gases, acid-base status, and electrolytes were assessed 30 and 60 min after drug injection. The DMB and DMM groups did not vary based on any of the evaluated variables. All animals developed hypoxaemia (PaO2 44 [30; 73] mmHg, SaO2 81 [62; 93] %) 30 min before O2 supplementation. Intranasal O2 at 2 L/min improved PaO2 (63 [49; 97] mmHg and SaO2 [92 [85; 98] %), but 9 of 12 capybaras remained hypoxaemic. A higher O2 flow of 5 L/min was efficient in treating hypoxaemia (PaO2 188 [146; 414] mmHg, SaO2 100 [99; 100] %) in all the 12 animals that received it. Both drug protocols induced hypoxaemia, which could be treated with intranasal oxygen supplementation

Effects of morphine and methadone on the behavior and tumor growth of mice with Ehrlich tumor

A morfina e a metadona, embora sejam fármacos recomendados para promover analgesia, parecem promover alterações comportamentais e influenciar no crescimento tumoral em modelos experimentais. Diante disso, o objetivo do estudo consistiu em avaliar os efeitos da morfina e metadona sobre o comportamento, antinocicepção e crescimento tumoral em camundongos. O estudo foi dividido em duas partes. No primeiro experimento foram utilizados 53 camundongos, fêmeas, com 60 ± 10 dias de idade que foram inoculados com tumor ascítico de Ehrlich (TAE) por via intraperitoneal. Após sete dias da inoculação, os animais foram distribuídos aleatoriamente em 7 grupos, morfina 5 mg/kg (Morf5), morfina 7,5 mg/kg (Morf7,5), morfina 10 mg/kg (Morf10), metadona 2,85 mg/kg (Met2,85), metadona 4,3 mg/kg (Met4,3), metadona 5,7 mg/kg (Met5,7) e solução salina NaCl 0,9% (Salina). Os tratamentos foram administrados por via subcutânea, a cada seis horas, durante três dias. Os animais foram avaliados quanto a atividade geral em campo aberto e nocicepção, por meio do teste de pinçamento de cauda, os quais foram realizados antes da inoculação tumoral (dia 0), aos 40, 90, 150, 240 e 360 minutos após o início dos tratamentos (dia 7) e 40, 150 e 360 minutos após os dias 8 e 9 pós-inoculação. Todas as doses promoveram aumento significativo da distância percorrida e velocidade média de maneira dose-dependente, sendo que os efeitos foram mais pronunciados nos dias 8 e 9. As frequências de levantar e de autolimpeza reduziram de maneira significativa após a administração de morfina e metadona em todas as doses até os 90 minutos. O segundo experimento consistiu em avaliar os efeitos sobre o crescimento tumoral das mesmas doses da morfina e metadona administradas por via subcutânea, a cada 6 horas, durante 8 dias, iniciados 24 horas após a inoculação tumoral. Os animais foram avaliados diariamente quanto ao peso e circunferência abdominal e nove dias após a inoculação tumoral, foram submetidos à eutanásia. O líquido ascítico foi colhido para aferição do volume, verificação da característica do líquido, contagem de células tumorais e análise do ciclo celular. Todos os animais apresentaram aumento de peso e de circunferência abdominal ao longo dos dias. O volume do líquido ascítico peritoneal foi menor nos tratamentos Morf5, Morf10 e em todas as doses testadas de metadona em comparação ao grupo Salina. A viabilidade e o número de células totais não diferiram entre os tratamentos. Os tratamentos Morf10 e Met5,7 interferiram no ciclo celular das células tumorais com maior porcentagem de células na fase G1 do ciclo, em comparação ao grupo Salina. Observou-se, a partir do primeiro experimento que todas as doses testadas promovem aumento da locomoção e redução de comportamentos exploratórios que foram mais evidentes ao longo dos dias de tratamento. A antinocicepção é observada por até 40 minutos em dose única e prolonga-se por até 150 minutos após administrações seriadas nas doses intermediárias e maiores. Os tratamentos Morf10 e Met5,7 promovem estase do ciclo celular, mas não interferem de maneira significativa no crescimento do tumor ascítico de Ehrlich.The objective of this research is to evaluate the effects of morphine and methadone on behavior, antinociception and tumor growth in mice. The study was dived into two parts. In the first experiment, Fifty-three female mice, 60 ± 10 days old, were inoculated with Ehrlich\'s ascitic tumor (EAT) intraperitoneally. Seven days after intraperitoneal tumour inoculation (2 × 106 cells), the animals were randomised into seven groups: morphine 5 mg/kg (MO5), morphine 7.5 mg/kg (MO7.5), morphine 10 mg/kg (MO10), methadone 2.85 mg/kg (ME2.85), methadone 4.3 mg/kg (ME4.3), methadone 5.7 mg/kg (ME5.7), and 0.9% NaCl (Sal). Treatments were administered subcutaneously, every 6 h, for 3 days. The animals were evaluated for general activity and nociception using the open field and tail clip tests, respectively. These tests were performed before tumour inoculation (day 0); at 40, 90, 150, 240, and 360 min following treatment initiation (day 7); and at 40, 150, and 360 min after days 8 and 9 post-inoculation. All evaluated doses promoted a significant dose-dependent increase in the total distance travelled and the average speed, markedly pronounced on days 8 and 9 than on day 7. The frequencies of rearing and self-grooming decreased significantly after morphine or methadone administration. The second experiment consisted of evaluating the effects on tumor growth of the same doses of morphine and methadone administered subcutaneously, every 6 hours, for 8 days, starting 24 hours after tumor inoculation. The animals were evaluated daily for weight and abdominal circumference and they were euthanized nine days after the tumor inoculation. The ascitic fluid was collected to measure the volume, check the characteristic of the liquid, count the tumor cells and analyze the cell cycle. All animals had increased weight and waist circumference over the days. The volume of peritoneal ascitic fluid was lower in the Morf5, Morf10 treatments and in all tested methadone doses compared to the Saline group. Viability and number of total cells did not differ between treatments. Morf10 and Met5,7 treatments interfered in the cell cycle of tumor cells, with a higher percentage of cells in the G1 phase of the cycle, compared to the Saline group. It was observed, from the first experiment, that all doses tested promote increased locomotion and reduced exploratory behaviors that were more evident over the treatment days. Antinociception was observed for up to 40 minutes in a single dose and continued for up to 150 minutes after serial administrations in intermediate and higher doses. The Morf10 and Met5,7 treatments promoted cell cycle stasis, but did not significantly interfere with the growth of Ehrlich\'s ascites tumor

Evaluation of Gastric pH and Gastrin Concentrations in Horses Subjected to General Inhalation Anesthesia in Dorsal Recumbency

The prevalence of gastric disorders in high-performance horses, especially gastric ulceration, ranges from 50 to 90%. These pathological conditions have negative impacts on athletic performance and health. This study was designed to evaluate changes in gastric pH during a 24 h period and to compare gastrin concentrations at different time points in horses undergoing general inhalation anesthesia and dorsal recumbency. Twenty-two mixed-breed mares weighing 400 ± 50 kg and aged 8 ± 2 years were used. Of these, eight were fasted for 8 h and submitted to 90 min of general inhalation anesthesia in dorsal recumbency. Gastric juice samples were collected prior to anesthesia (T0), and then at 15 min intervals during anesthesia (T15–T90). After recovery from anesthesia (45 ± 1 min), samples were collected every hour for 24 h (T1 to T24) for gastric juice pH measurement. During this period, mares had free access to Bermuda grass hay and water and were fed a commercial concentrate twice (T4 and T16). In a second group (control), four non-anesthetized mares were submitted to 8 h of fasting followed by nasogastric intubation. Gastric juice samples were then collected at T0, T15, T30, T45, T60, T75, and T90. During this period, mares did not receive food or water. After 45 min, mares had free access to Bermuda grass hay and water, and gastric juice samples were collected every hour for four hours (T1 to T4). In a third group comprising ten non-fasted, non-anesthetized mares with free access to Bermuda grass hay and water, gastric juice samples were collected 30 min after concentrate intake (T0). In anesthetized mares, blood gastrin levels were measured prior to anesthesia (8 h fasting; baseline), during recovery from anesthesia, and 4 months after the anesthetic procedure, 90 min after the morning meal. Mean values of gastric juice pH remained acidic during general anesthesia. Mean pH values were within the physiological range (4.52 ± 1.69) and did not differ significantly between time points (T15–T90; p  >  0.05). After recovery from anesthesia, mean gastric pH values increased and remained in the alkaline range throughout the 24 h period of evaluation. Significant differences were observed between T0 (4.88 ± 2.38), T5 (7.08 ± 0.89), T8 (7.43 ± 0.22), T9 (7.28 ± 0.36), T11 (7.26 ± 0.71), T13 (6.74 ± 0.90), and T17 (6.94 ± 1.04) (p  p  <  0.05). General inhalation anesthesia and dorsal recumbency did not affect gastric juice pH, which remained acidic and within the physiological range. Gastric juice pH was weakly alkaline after recovery from anesthesia and in the fasted and fed states. Serum gastrin levels increased in response to general inhalation anesthesia in dorsal recumbency and were not influenced by fasting. Preventive pharmacological measures are not required in horses submitted to general anesthesia and dorsal recumbency