Xylazine and ketamine anaesthesia in the dromedary camel under field conditions

The effects of either xylazine (0.25 mg/kg) intramuscularly, ketamine (5.5 mg/kg) intramuscularly, or a mixture of xylazine (0.15 mg/kg) and ketamine (2.5 mg/kg) intramuscularly on sedation, analgesia, cardiac and respiratory rates, body temperature and muscle relaxation were studied in the domesticated dromedary camel. Either drug used separately was suitable for sedation and analgesia in the camel. However, the mixture of xylazine and ketamine was superior to either drug used alone. Camels which received the combination of xylazine and ketamine had fewer effects on cardiac and respiratory rates and better analgesia. In addition, they showed better muscle relaxation, less central nervous system irritability and shorter recovery times than camels sedated with ketamine alone.     

Comparison of quality of induction of anaesthesia between intramuscularly administered ketamine, intravenously administered ketamine and intravenously administered propofol in xylazine premedicated cats

The quality of induction of general anesthesia produced by ketamine and propofol, 2 of the most commonly used anaesthetic agents in cats, was assessed. Eighteen cats admitted for elective procedures were randomly assigned to 3 groups and then premedicated with xylazine 0.75 mg/kg intramuscularly before anaesthesia was induced with ketamine 15 mg/kg intramuscularly (KetIM group), ketamine 10 mg/kg intravenously (KetIV group) or propofol 4 mg/kg intravenously (PropIV group). Quality of induction of general anaesthesia was determined by scoring ease of intubation, degree of struggling, and vocalisation during the induction period. The quality of induction of anaesthesia of intramuscularly administered ketamine was inferior to that of intravenously administered ketamine, while intravenously administered propofol showed little difference in quality of induction from ketamine administered by both the intramuscular and intravenous routes. There were no significant differences between groups in the ease of intubation scores, while vocalisation and struggling were more common in cats that received ketamine intramuscularly than in those that received intravenously administered ketamine or propofol for induction of anaesthesia. Laryngospasms occurred in 2 cats that received propofol. The heart rates and respiratory rates decreased after xylazine premedication and either remained the same or decreased further after induction for all 3 groups, but remained within normal acceptable limits. This study indicates that the 3 regimens are associated with acceptable induction characteristics, but administration of ketamine intravenously is superior to its administration intramuscularly and laryngeal desensitisation is recommended to avoid laryngospasms.     

A dose titration study into the effects of diazepam or midazolam on the propofol dose requirements for induction of general anaesthesia in client owned dogs,premedicated with methadone and acepromazine

ObjectiveTo assess the effect of a benzodiazepine co–induction on propofol dose requirement for induction of anaesthesia in healthy dogs, to describe any differences between midazolam and diazepam and to determine an optimal benzodiazepine dose for co–induction.Study designProspective, randomised, blinded placebo controlled clinical trial.AnimalsNinety client owned dogs (ASA I–III, median body mass 21.5kg (IQR 10–33)) presented for anaesthesia for a variety of procedures.MethodsDogs were randomised to receive saline 0.1 mL kg^?1, midazolam or diazepam at 0.2, 0.3, 0.4 or 0.5 mg kg^?1. All dogs received 0.01 mg kg^?1 acepromazine and 0.2 mg kg^?1 methadone intravenously (IV). Fifteen minutes later, sedation was assessed and scored prior to anaesthetic induction. Propofol, 1 mg kg^?1, was administered IV, followed by the treatment drug. Further propofol was administered until endotracheal intubation was possible. Recorded data included patient signalment, sedation score, propofol dosage and any adverse reactions.ResultsMidazolam (all groups combined) significantly reduced propofol dose requirement compared to saline (p < 0.001) and diazepam (p = 0.008). Midazolam (0.4 mg kg^?1) significantly reduced propofol dose requirement (p = 0.014) compared to saline, however other doses failed to reach statistical significance. Diazepam did not significantly reduce propofol dose requirement compared to saline (p = 0.089). Dogs weighing <5 kg, regardless of treatment group, required a greater propofol dose than those weighing 5–40 kg (p = 0.002) and those >40 kg (p = 0.008). Dogs which were profoundly sedated required less propofol than those which were mildly sedated (p < 0.001) and adequately sedated (p = 0.003).Conclusions and clinical relevanceMidazolam (0.4 mg kg^?1) given IV after 1 mg kg^?1 of propofol significantly reduced the further propofol dose required for intubation compared to saline. At the investigated doses, diazepam did not have significant propofol dose sparing effects.     

Total intravenous anaesthesia with propofol or propofol/ketamine in spontaneously breathing dogs premedicated with medetomidine

The cardiorespiratory parameters, the depth of anaesthesia and the quality of recovery were evaluated in six spontaneously breathing dogs that had been premedicated with medetomidine (40 microg/kg, supplemented with 20 microg/kg an hour later), administered with either propofol (1 mg/kg followed by 0.15 mg/kg/minute, intravenously), or with ketamine (1 mg/kg followed by 2 mg/kg/hour, intravenously) and propofol (0.5 mg/kg followed by 0.075 mg/kg/minute, intravenously). The dogs' heart rate and mean arterial blood pressure were higher and their minute volume of respiration and temperature were lower when they were anaesthetised with propofol plus ketamine, and a progressive hypercapnia leading to respiratory acidosis was more pronounced. When the dogs were anaesthetised with propofol/ketamine they recovered more quickly, but suffered some unwanted side effects. When the dogs were anaesthetised with propofol alone they recovered more slowly but uneventfully.     

Effects of dietary corticosterone in young Leghorn and meat-type cockerels

1. Cockerels from meat-type (MT) and Leghorn (LG) stocks were fed on diets containing 0, 20, or 30 mg corticosterone/kg from 1 to 22 d after hatching. 2. Within MT and within LG stocks, responses to dietary corticosterone inclusion rates were similar; however, patterns differed between these major classes resulting in stock X diet interactions. 3. Traits responding to different inclusion rates of corticosterone in a dissimilar manner for MT and LG chickens included: immunoresponsiveness, body weight, efficiency of food utilisation, feathering; relative weights of liver, spleen, bursa, testes, breast and abdominal fat pad, as well as the proportion of liver lipid. 4. No differential responses occurred for relative adrenal weight, plasma xanthophyll concentrations, proportion of breast lipid and abdominal fat, or surface and cloacal temperatures. 5. Results indicated genetic differences in thresholds for response to corticosterone and in degree of response once thresholds were reached. Within populations, sensitivities varied between target organs.     

Antagonistic effects of atipamezole, flumazenil and 4-aminopyridine against anaesthesia with medetomidine, midazolam and ketamine combination in cats

Antagonistic effects of atipamezole (ATI), flumazenil (FLU) and 4-aminopyridine (4AP) alone and in various combinations after administration of medetomidine-midazolam-ketamine (MED-MID-KET) were evaluated in cats. Animals were anaesthetised with MED (50 microg/kg), MID (0.5 mg/kg) and KET (10 mg/kg) given intramuscularly. Twenty minutes later, physiological saline, ATI (200 microg/kg), FLU (0.1 mg/kg), 4AP (0.5 mg/kg), ATI-FLU, FLU-4AP, ATI-4AP or ATI-FLU-4AP was administered intravenously. FLU, 4AP alone, or FLU-4AP did not effectively antagonise the anaesthesia, hypothermia, bradycardia, and bradypnoea induced by MED-MID-KET. ATI alone was effective. ATI-FLU, ATI-4AP and ATI-FLU-4AP combinations produced an immediate and effective recovery from anaesthesia. The combination of ATI-FLU-4AP was the most effective in antagonising the anaesthetic effects, but was associated with tachycardia, tachypnoea, excitement, and muscle tremors. Combinations with ATI are more effective for antagonising anaesthesia, but ATI-FLU-4AP is not suitable.     

Effect of hypothalamic electrolytic lesions in White Leghorn and broiler male cockerels

1. This study compared the effect of bilateral electrolytic lesions of the basomedial hypothalamus (HL) in broiler and White Leghorn (WL) males. 2. Hypothalamic lesions were placed in WL at 10 weeks of age (body weight 1.1 kg) and in broilers, either at 6 weeks (body weight 1.5kg) or at 10 weeks of age (body weight 3.4kg). They were fed ad libitum until autopsy at 16 and 17 weeks of age for broilers and WL, respectively. 3. Hypothalamic lesions caused obesity (high percentage weight of abdominal adipose tissue) in both strains. Obese fowls with unimpaired reproductive systems were classified as OB and those with functional castration as FC (functionally castrated) or FCLC (functionally castrated with large comb). 4. All post-HL syndromes-OB, FC and FCLC-were present in WL, whereas all obese broilers (which are immature at this age) were classified as OB. 5. The percentage weight of abdominal adipose tissue in OB broilers was lower than in OB WL (3% vs 5%, respectively). 6. Daily food intake of OB broilers was higher than control at 12 to 15 weeks of age, regardless of time of placement of HL, whereas daily food intake of OB WL was significantly higher than that of control WL only during the first 2 weeks following HL. 7. Body weight of OB broilers at autopsy was 20% higher than control broilers, whereas body weight of OB WL was not significantly affected. 8. An additional group of broilers was reared to sexual maturity under food restriction until 28 weeks of age. HL were placed at 10 weeks of age (body weight 1.7 kg). Autopsy was performed after a 4-week period of ad libitum feeding. 9. There were OB as well as FC and FCLC among the HL, food-restricted broilers. Percentage weight of testes and spleen were reduced in OB fowls of both strains, but more so in OB WL. 10. Hyperphagia and weight gain were not observed during the ad libitum feeding period of those obese broilers after HL, indicating that hyperphagia and weight gain are secondary to obesity.     

Response of White Leghorn and Nigerian cockerels to experimental salmonella infection

Summary Twenty-two Nigerian cockerels and 19 White Leghorn cockerels were each injected intramuscularly with 1·5×10⁹ viable organisms of a relatively avirulent strain ofSalmonella gallinarum (NCTC 10532). The Nigerian cockerels were more resistant to infection as judged by the values of the haemoglobin, haematocrit, red cell count, leucocyte count and antibody titre during the course of infection. The authors suggest that the higher resistance may be due to the earlier growth and higher organ weight of the bursa of Fabricius of the Nigerian breed than of the White Leghorn (Aire,1973).

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Sumario Ventidos pollos Nigerianos y diecinueve White Leghorn fueron inoculados individualmente vía intramuscular, con 1·5 × 10⁹ de una suspensión relativamente avirulenta de una cepa deSalmonella gallinarum (NCTC 10532). Los pollos Nigerianos fueron más resistentes a la infección, teniendo en cuenta los valores de hemaglobina, hematocrito, número de globulos rojos, leucocitos y título de anticuerpos durante el curso de la infección. Los autores sugieren, que la mayor resistencia de la raza Nigeriana, podría estar relacionada con el peso y desarrollo mástemprano de la bolsa de Fabricius.

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Résumé Trente deux coquelets Nigériens et dix neuf coquelets Leghorn blancs ont été infectés, chacun par une injection intramusculaire de 1·5 × 10⁹ germes vivants d'une souche relativement avirulente deSalmonella gallinarum (NCTC 10532). L'examen, tout au long de l'expérience, de l'hémoglobine, des hématocrites, la numération des hématies et des leucocytes et le titrage des anticorps ont montré que les coquelets Nigériens étaient plus résistants. Les auteurs suggèrent que cette résistance supérieure peut être due au développement plus précoce et au poids supérieur de la bourse Fabricius chez le coquelet Nigérien par rapport au coquelet Leghorn blanc (Aire, 1973).

     

Pharmacokinetics of intramuscular ketamine in young ostriches premedicated with romifidine

Ketamine is a short-acting dissociative anaesthetic for chemical restraint and surgical anaesthesia in domestic and non-domestic animals. The present study was designed to determine the pharmacokinetics of a single dose of ketamine (10 mg/kg) after intramuscular (i.m.) administration to young ostriches premedicated with romifidine. Ketamine was rapidly absorbed after i.m. administration. Maximal ketamine concentration (C(max)) of 2.93 +/- 0.61 microg/ml was reached at 12.5 +/- 2.50 min and thereafter ketamine concentrations decreased rapidly. The elimination half-life (t(1/2 z)) obtained was 62.37 +/- 17.37 min and mean residence time (MRT) was 77.33 +/- 19.12 min. The area under the curve (AUC) was 114.19 +/- 15.76 microg x min/ml.     

Echocardiographic evaluation including tissue Doppler imaging in New Zealand white rabbits sedated with ketamine and midazolam

Limited data are available on the use of more recent echocardiographic parameters in the rabbit. Echocardiographic examination, including conventional echocardiography and tissue Doppler imaging (TDI), was performed on 26 male New Zealand white rabbits under ketamine–midazolam sedation. Particular emphasis was placed on the more recent systolic and diastolic parameters, such as myocardial performance index (Tei index) and mitral annular motion (from septal and lateral sides of the left ventricle) obtained using pulsed TDI.Parameters that assessed systolic and diastolic function (fractional shortening, Tei index, and maximal mitral E- and A-wave velocities) were comparable to those reported in the literature for rabbits in the awake state. The less cardiodepressive anaesthetic protocol could offer a good alternative in performing echocardiographic evaluation whenever such caution is necessary. TDI is feasible in healthy rabbits and potentially suitable for the investigation of left ventricle systolic and diastolic function.     

A comparison of two different ketamine and diazepam combinations with an alphaxalone and medetomidine combination for induction of anaesthesia in sheep

Abstract

AIMS: To investigate the perceived adverse effects of a particular batch of ketamine during induction of anaesthesia in sheep and to assess if any adverse effects would make intubation more difficult for the veterinary students.

METHODS: Thirty adult sheep (mean bodyweight 74.5 (SD 9.4) kg) were randomly assigned to one of six groups of five sheep. Sheep in Groups A and B received I/V 0.5 mg/kg diazepam and 10 mg/kg ketamine (Ketamine Injection; Parnell Laboratories NZ Ltd, of the suspect batch); those in Groups C and D received I/V 0.5 mg/kg diazepam and 10 mg/kg ketamine (Ketalar; Hospira NZ Ltd.), and those in Groups E and F received I/V 2 μg/kg medetomidine and 2 mg/kg alphaxalone. In Groups A, C and E, intubation was by an experienced anaesthetist, and in Groups B, D and F intubation was by a veterinary student. Time from injection to successful intubation, the ease of intubation, saturation of haemoglobin with oxygen (SpO₂) and partial pressure of oxygen in arterial blood (PaO₂) were measured before the sheep were connected to an anaesthetic machine and allowed to breath oxygen. Times to extubation, holding its head up and standing, maximum and minimum heart rates, respiratory rates, maximal end tidal CO₂, and the quality of recovery were then recorded.

RESULTS: There were no measurable differences in outcomes between sheep in Groups A and B compared with C and D. Time to intubation was slightly shorter for the experienced anaesthetist than the student, but the difference was not significant. The sheep in Groups E and F took less time to recover than those in Groups A?D (p<0.05), but there were no significant differences between the groups in either the ease of induction or quality of recovery. Most sheep in Groups E and F showed minor excitatory effects, mainly at induction, which did not interfere with induction. Respiratory rates were lower in Groups E and F than Groups A?D (p<0.01), but SpO₂ was higher in Groups E and F than A and B (p<0.05).

CONCLUSIONS: The clinical impression that the batch of Parnell ketamine produced unexpected effects was shown to be incorrect. All the combinations produced anaesthesia that allowed intubation by the veterinary student.

CLINICAL RELEVANCE: All the drug combinations produced satisfactory anaesthesia in sheep, but the alphaxaloneand medetomidine combination resulted in faster recovery.     

The effects of diazepam or midazolam on the dose of propofol required to induce anaesthesia in cats

ObjectivesAssess effects of benzodiazepine administration on the propofol dose required to induce anaesthesia in healthy cats, investigate differences between midazolam and diazepam, and determine an optimal benzodiazepine dose for co-induction.Study designProspective, randomised, blinded, placebo-controlled clinical trial.AnimalsNinety client-owned cats (ASA I and II) with a median (interquartile range) body mass of 4.0 (3.4–4.9) kg.MethodsAll cats received 0.01 mg kg⁻¹ acepromazine and 0.2 mg kg⁻¹ methadone intravenously (IV). Fifteen minutes later, sedation was scored on a scale of 1–5, with 5 indicating greatest sedation. Propofol, 2 mg kg⁻¹, administered IV, was followed by either midazolam or diazepam at 0.2, 0.3, 0.4 or 0.5 mg kg⁻¹ or saline 0.1 mL kg⁻¹. Further propofol was administered until endotracheal intubation was possible. Patient signalment, sedation score, propofol dosage and adverse reactions were recorded.ResultsMidazolam and diazepam (all doses) significantly reduced the propofol dose required compared with saline (p < 0.001). There was no difference between midazolam and diazepam in propofol dose reduction (p = 0.488). All individual doses of midazolam reduced propofol requirement compared with saline (0.2 mg kg⁻¹, p = 0.028; 0.3 mg kg⁻¹, p = 0.006; 0.4 mg kg⁻¹, p < 0.001; 0.5 mg kg⁻¹, p = 0.009). Diazepam 0.2 mg kg⁻¹ did not reduce the propofol dose compared with saline (p = 0.087), but the remaining doses did (0.3 mg kg⁻¹, p = 0.001; 0.4 mg kg⁻¹, p = 0.032; 0.5 mg kg⁻¹, p = 0.041). Cats with sedation scores of 3 required less propofol than cats with scores of 2 (p = 0.008). There was no difference between groups in adverse events.Conclusions and clinical relevanceMidazolam (0.2–0.5 mg kg⁻¹) and diazepam (0.3–0.5 mg kg⁻¹) administered IV after 2 mg kg⁻¹ propofol significantly reduced the propofol dose required for tracheal intubation.     

Anaesthesia with midazolam/medetomidine/fentanyl in chinchillas (Chinchilla lanigera) compared to anaesthesia with xylazine/ketamine and medetomidine/ketamine

We studied four different drug regimes for anaesthetic management in chinchillas and evaluated and compared their cardiovascular and respiratory effects. In this randomized, cross-over experimental study, seven adult chinchillas, five females, two males [515 +/- 70 (SD) g] were randomly assigned to one of the following groups: group 1 [midazolam, medetomidine and fentanyl (MMF), flumazenil, atipamezole and naloxone (FAN); MMF-FAN] received 1.0 mg/kg midazolam, 0.05 mg/kg medetomidine and 0.02 mg/kg fentanyl i.m., and for reversal 0.1 mg/kg flumazenil, 0.5 mg/kg atipamezole and 0.05 mg/kg naloxone s.c. after 45 min; group 2 (MMF) 1.0 mg/kg midazolam, 0.05 mg/kg medetomidine and 0.02 mg/kg fentanyl i.m.; group 3 [xylazine/ketamine (X/K)] 2.0 mg/kg xylazine and 40.0 mg/kg ketamine i.m.; and group 4 [medetomidine/ketamine (M/K)] 0.06 mg/kg medetomidine and 5.0 mg/kg ketamine i.m. Reflexes were judged to determine anaesthetic stages and planes. Anaesthesia with X/K and M/K was associated with a prolonged surgical tolerance and recovery period. By reversing MMF, recovery period was significantly shortened (5 +/- 1.3 min versus 40 +/- 10.3 min in MMF without FAN, 73 +/- 15.0 min in X/K, and 31 +/- 8.5 min in M/K). Without reversal, MMF produced anaesthesia lasting 109 +/- 16.3 min. All combinations decreased respiratory and heart rate but compared with X/K and M/K, respiratory and cardiovascular complications were less in the MMF groups. Focussing on the clinical relevance of the tested combinations, completely reversible anaesthesia showed two major advantages: anaesthesia can be antagonized in case of emergency and routinely shortens recovery. In small animals particularly these advantages lead to less complications and discomfort and thus often can be lifesaving. As all analgesic components (medetomidine and fentanyl) are reversed, postoperative analgesia should be provided before reversal of anaesthesia.     

The use of propofol for induction of anaesthesia in dogs premedicated with acepromazine, butorphanol and acepromazine-butorphanol

Cardiovascular, pulmonary and anaesthetic-analgesic responses were evaluated in 18 male and female dogs to determine the effect of the injectable anaesthetic propofol used in conjuction with acepromazine and butorphanol. The dogs were randomly divided into three groups. Dogs in Group A were premeditated with 0.1 mg/kg of intramuscular acepromazine followed by an induction dose of 4.4 mg/kg of intravenous propofol; Group B received 0.2 mg/kg of intramuscular butorphanol and 4.4 mg/kg of intravenous propofol; dogs in Group AB were administered a premeditation combination of 0.1 mg/kg of intramuscular acepromazine and 0.2 mg/kg of intramuscular butorphanol, followed by induction with 3.3 mg/kg of intravenous propofol. The induction dose of propofol was given over a period of 30-60 seconds to determine responses and duration of anaesthesia. Observations recorded in the dogs included heart and respiratory rates, indirect arterial blood pressures (systolic, diastolic and mean), cardiac rhythm, end-tidal CO, tension, oxygen saturation, induction time, duration of anaesthesia, recovery time and adverse reactions. The depth of anaesthesia was assessed by the response to mechanical noxious stimuli (tail clamping), the degree of muscle relaxation and the strength of reflexes. Significant respiratory depression was seen after propofol induction in both groups receiving butorphanol with or without acepromazine. The incidence of apnea was 4/6 dogs in Group B, and 5/6 dogs in Group AB. The incidence of apnea was also correlated to the rate of propofol administration. Propofol-mediated decreases in arterial blood pressure were observed in all three groups. Moderate bradycardia (minimum value > 55 beats/min) was observed in both Groups B and AB. There were no cardiac dysrhythmias noted in any of the 18 dogs. The anaesthetic duration and recovery times were longer in dogs premeditated with acepromazine/butorphanol.