Comparison between total intravenous anesthesia with propofol and intermittent bolus of tiletamine-zolazepam in capuchin monkey (Sapajus apella) / Comparação entre anestesia total intravenosa com propofol e bolus intermitente de tiletamina-zolazepam em macaco-prego (Sapajus apella)

Dissociative anesthesia results in stressful and long recovery periods in monkeys and use of injectable anesthetics in medical research has to be refined. Propofol has promoted more pleasure wake up from anesthesia. The objectives of this study were to investigate the use of intravenous anesthetic propofol, establishing the required infusion rate to maintain surgical anesthetic level and comparing it to tiletamine-zolazepam anesthesia in Sapajus apella. Eight healthy capuchin monkeys, premedicated with midazolam and meperidine, were anesthetized with propofol (PRO) or tiletamine-zolazepam (TZ) during 60 minutes. Propofol was infused continually and rate was titrated to effect and tiletamine-zolazepam was given at 5mg/kg IV bolus initially and repeated at 2.5mg/kg IV bolus as required. Cardiopulmonary parameters, arterial blood gases, cortisol, lactate and quality and times to recovery were determined. Recovery quality was superior in PRO. Ventral recumbency (PRO = 43.0±21.4 vs TZ = 219.3±139.7 min) and normal ambulation (PRO = 93±27.1 vs TZ = 493.7±47.8 min) were faster in PRO (p<0.05). Cardiopulmonary effects did not have marked differences between groups. Median for induction doses of propofol was 5.9mg/kg, varying from 4.7 to 6.7mg/kg, Mean infusion rate was 0.37±0.11mg/kg/min, varying during the one-hour period. In TZ, two animals required three and five extra doses. Compared to tiletamine-zolazepam, minor post-anesthetic adverse events should be expected with propofol anesthesia due to the faster and superior anesthetic recovery. (AU)

A anestesia dissociativa em primatas resulta em recuperação anestésica lenta e estressante, e, portanto, o uso de anestesia injetável em pesquisas médicas precisa ser refinado. Por outro lado, o propofol promove recuperação mais suave. Os objetivos desse estudo foram investigar o uso do anestésico intravenoso propofol, estabelecer a taxa de infusão contínua necessária para manter anestesia cirúrgica, e comparar tal técnica com a dissociativa tiletamina-zolazepam em Sapajus apella. Oito macacos-prego saudáveis foram pré-medicados com midazolam e meperidina, e posteriormente anestesiados com propofol (PRO) ou tiletamina-zolazepam (TZ) durante 60 minutos. O propofol foi administrado em infusão contínua, e a taxa foi titulada ao efeito, já a tiletamina-zolazepam foi administrada em 5mg/kg IV como bolus inicial, e repiques de 2,5mg/kg IV conforme necessário. Os parâmetros cardiopulmonares, hemogasometria arterial, cortisol, e lactato, além da qualidade e duração da recuperação anestésica foram determinados. A qualidade da recuperação anestésica foi superior em PRO. O tempo para atingir decúbito ventral (PRO = 43,0±21,4 vs TZ = 219,3±139,7 min) e ambulação normal (PRO = 93±27,1 vs TZ = 493,7±47,8 min) foram mais rápidos em PRO (p<0,05). As variáveis cardiopulmonares não diferiram entre os grupos. A mediana para dose de indução com propofol foi de 5,9mg/kg, variando de 4,7 a 6,7mg/kg. A taxa de infusão contínua média de propofol foi de 0,37±0,11mg/kg/min, variando ao longo dos 60 minutos. Em TZ, dois animais necessitaram de três e cinco repiques. Comparado à tiletamina-zolazepam, menos efeitos adversos pós-anestésicos devem ser esperados com o propofol, devido à recuperação mais suave e rápida.(AU)

Sedative and electrocardiographic effects of low dose dexmedetomidine in healthy cats / Efeitos sedativos e eletrocardiográficos da baixa dose de dexmedetomidina em gatos saudáveis

In feline veterinary practice sedation is often needed to perform diagnostic or minimally invasive procedures, minimize stress, and facilitate handling. The mortality rate of cats undergoing sedation is significantly higher than dogs, so it is fundamental that the sedatives provide good cardiovascular stability. Dexmedetomidine (DEX) is an α2-adrenergic receptor agonist utilized in cats to provide sedation and analgesia, although studies have been utilized high doses, and markedly hemodynamic impairments were reported. The aim of this study was to prospectively investigate how the sedative and electrocardiographic effects of a low dose of DEX performing in cats. Eleven healthy cats were recruited; baseline sedative score, systolic arterial pressure, electrocardiography, and vasovagal tonus index (VVTI) were assessed, and repeated after ten minutes of DEX 5μg/kg intramuscularly (IM). A smooth sedation was noticed, and emesis and sialorrhea were common adverse effects, observed on average seven minutes after IM injection. Furthermore, electrocardiographic effects of a low dose of DEX mainly include decreases on heart rate, and increases on T-wave amplitude. The augmentation on VVTI and appearance of respiratory sinus arrhythmia, as well as sinus bradycardia in some cats, suggesting that DEX enhances parasympathetic tonus in healthy cats, and therefore will be best avoid in patients at risk for bradycardia.(AU)

Na rotina clínica da medicina veterinária felina a sedação é frequentemente requerida para realização de procedimentos diagnósticos ou minimamente invasivos, para minimizar o estresse e facilitar o manuseio dos pacientes. A taxa de mortalidade de gatos submetidos à sedação é mais elevada do que em cães, por esse motivo, é fundamental que os sedativos confiram estabilidade hemodinâmica. A dexmedetomidina (DEX) é um α2-agonista utilizado em felinos para promover sedação e analgesia, porém os estudos têm utilizado doses elevadas, e com isso prejuízos hemodinâmicos importantes foram relatados. O objetivo desta investigação foi avaliar os efeitos sedativos e eletrocardiográficos da baixa dose de DEX em gatos. Para tal, onze felinos saudáveis foram recrutados, foram obtidos valores basais para escore de sedação, pressão arterial sistólica e eletrocardiografia, além do índice de tônus vaso vagal (ITVV). Após dez minutos da aplicação intramuscular (IM) de DEX 5μg/kg todos os exames foram repetidos. Após a DEX, sedação suave foi detectada, e a êmese e sialorreia foram efeitos adversos comuns, observados em média 7 minutos após a injeção IM. Ademais, os principais efeitos eletrocardiográficos foram redução na frequência cardíaca e aumento na amplitude da onda T. O ITVV mais elevado e surgimento de arritmia sinusal respiratória, bem como bradicardia sinusal em alguns gatos, sugerem que a DEX eleva o tônus parassimpático, e por esse motivo deve ser utilizada com cautela em pacientes com predisposição à bradicardia.(AU)

Dexmedetomidine low dose followed by constant rate infusion and antagonism by atipamezole in isoflurane-anesthetized cats: an echocardiographic study.

OBJECTIVE: To investigate the effects of a low dose of dexmedetomidine (DEX) followed by constant rate infusion (CRI) and reversal with atipamezole on systolic and diastolic functions in isoflurane-anesthetized healthy cats. STUDY DESIGN: Prospective cohort study. ANIMALS: A group of 11 client-owned adult cats. METHODS: Baseline transthoracic echocardiography (TTE) was performed, followed by intramuscular (IM) administration of DEX (5 µg kg-1). After 10 minutes, sedation was scored, adverse effects were recorded and another TTE performed. Approximately 40 minutes after DEX administration, anesthesia was induced by isoflurane mask and maintained with 1.2% end-tidal isoflurane and DEX CRI (1 µg kg-1 hour-1) for 80 minutes. Physiological variables were recorded every 10 minutes, and TTE was repeated 10, 30 and 60 minutes after the start of anesthesia. CRI was stopped, atipamezole (30 µg kg-1) was administered IM and a final TTE was performed after 10 minutes. Repeated measures over time were submitted to one-way analysis of variance or Kruskal-Wallis test according to data distribution; significance was assumed at p < 0.05. RESULTS: After DEX premedication, mild sedation and a slight but significant increase in systolic arterial pressure occurred, and vomiting was a common adverse effect. The cardiac output (CO) and heart rate decreased during anesthesia, with no changes after administration of atipamezole. Trivial valvular insufficiencies were commonly seen after DEX premedication and during CRI. Myocardial radial and longitudinal systolic functions were not affected by sedation or by anesthesia. The late phase of diastole on both right and left ventricles was affected by isoflurane-DEX CRI. Global left ventricular myocardial performance was not impaired. CONCLUSIONS: and clinical relevance Decreased CO and late diastolic impairment were observed in healthy cats administered a low dose of DEX for premedication followed by anesthesia with isoflurane and DEX CRI.

Continuous infusion of propofol or intermittent bolus of tiletamine-zolazepam in squirrel monkeys (Saimiri sciureus).

OBJECTIVE: To investigate an infusion of propofol for anesthesia in comparison to tiletamine-zolazepam anesthesia, evaluating physiological variables and recovery in squirrel monkeys. STUDY DESIGN: Prospective non-blinded randomized study. ANIMALS: Eight healthy squirrel monkeys (Saimiri sciureus), aged 3 years and weighing 0.340-0.695 kg. METHODS: Premedication was intramuscular midazolam (0.5 mg) and meperidine (4 mg). Anesthesia was induced with intravenous (IV) propofol (4 mg kg(-1)  minute(-1) ) and maintained with propofol starting at 0.4 mg kg(-1)  minute(-1) (PRO, n = 4) or IV tiletamine-zolazepam (5 mg kg(-1) ) and maintained with supplementary doses of TZ (TZ, n = 4). Cardiopulmonary variables were measured continuously. Arterial blood gases and lactate concentration were measured at the end of anesthesia. Quality and times of recovery were determined. Repeatedly measured data for significant differences were tested between groups with t-test and within groups by anova. RESULTS: Median time for induction of anesthesia in PRO was 180 seconds. Mean maintenance infusion rate of propofol was 0.43 ± 0.05 mg kg(-1)  minute(-1) , varying during the 1 hour period. One monkey died after administration of TZ; others required 1, 4, or 8 supplemental doses. Cardiopulmonary variables were similar between groups, but hypotension was recorded. Recovery times to ventral recumbency in PRO (32 ± 17 minutes) and TZ (84 ± 11 minutes) and normal ambulation in PRO (58 ± 22 minutes) and TZ (358 ± 109minutes) were significantly different (p < 0.05). Recovery quality was superior in PRO, with less ataxia and fewer unsuccessful attempts to stand. Lactate concentration was not different between treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Cardiopulmonary variables were similar between protocols, aside from the higher incidence of hypotension in PRO, indicating that further studies with a larger number of animals are required. Compared to tiletamine-zolazepam, propofol anesthesia provided faster and superior anesthetic recovery in these animals.

Continuous infusion of propofol or intermittent bolus of tiletamine-zolazepam in feline night monkeys (Aotus infulatus).

BACKGROUND: Although commonly used, dissociative anesthesia results in unsatisfactory and long recovery periods. The intravenous anesthetic propofol seems to be the most advantageous solution. The objectives of this study were to investigate the required infusion rate of propofol to maintain surgical anesthesia and to compare it to tiletamine-zolazepam in Aotus infulatus. METHODS: Eight healthy feline night monkeys were anesthetized with propofol (PRO) or tiletamine-zolazepam (TZ) during 60 minutes. Cardiopulmonary parameters, arterial blood gases and lactate and quality and times to recovery were determined. RESULTS: Mean infusion rate of propofol was 0.53 ± 0.10 mg/kg/minute. Cardiopulmonary effects did not show marked differences between groups. Times for hanging, ventral recumbency, and normal ambulation were lower in PRO. Establishment of desirable anesthetic depth was easier, recovery quality was superior, and lactate levels were lower in PRO. CONCLUSIONS: Compared with tiletamine-zolazepam, minor post-anesthetic adverse events should be expected with propofol anesthesia, as well as faster and better anesthetic recovery.

Bilateral phacoemulsification in an orangutan (Pongo pygmaeus).

A 14-year-old, female, captive-born orangutan (Pongo pygmaeus) developed bilateral cataracts. Ultrasonography, electroretinography and cataract correction using phacoemulsification were performed bilaterally. This case report aims to describe the ophthalmic procedures performed in this animal critically endangered of extinction. The surgery successfully restored vision and normal activity to the patient.

The capybara eye: clinical tests, anatomic and biometric features.

PURPOSE: To carry out a descriptive investigation of the capybara (Hydrochaeris hydrochaeris) eye and to perform selected ophthalmic diagnostic tests with the aim of establishing normal physiological reference values for this species. METHOD: A total of 22 healthy, capybaras were used to test most of the parameters in this investigation. Ages varied from 2 to 4 years of age. Selected diagnostic ocular tests were performed including Schirmer tear test, tonometry using an applanation tonometer (Tonopen), central corneal thickness using an ultrasonic pachymeter (Sonomed, Micropach, Model 200P +), axial globe length and culture of the normal conjunctival bacterial flora. RESULTS AND DISCUSSION: Capybara's normal ocular features include: dorsal and ventral puncta, vestigial third eyelid, true cilia only at the upper eyelid margins. The bulbar conjunctiva is noticeably densely pigmented with a brown to bronze color. The capybara's pupil is oval in shape and vertical in position No tapetum lucidum is present in this species and the retinal blood vessels are almost absent. Results for selected ocular diagnostic tests investigated were: Intraocular pressure: 18.4 +/- 3.8 mmHg; Schirmer tear test: 14.9 +/- 5.1 mm/min; Central corneal thickness: 0.46 +/- 0.03 mm; Axial globe length: 22.20 +/- 1.71 mm. No statistically significant differences between ages or genders were found for any of the results. Corynebacterium sp., Micrococcus sp., Bacillus sp. and Staphylococcus sp. were isolated from healthy conjunctiva, suggesting they are normal constituents of the conjunctival flora of the capybara eye. The corneal epithelium of the capybara possesses a thin and discrete Bowman's layer. Results and parameters obtained in this investigation exposed unique anatomic features of the capybara eye and will help veterinary ophthalmologists to more accurately diagnose discrete or unusual pathological changes of the capybara eye. Furthermore, corneal thickness and axial length of the capybara are similar to that of human beings, revealing that the world's largest living rodent might be an excellent biological model for ophthalmic studies.

Reference values for selected ophthalmic diagnostic tests of the capuchin monkey (Cebus apella).

PURPOSE: To perform selected ophthalmic diagnostic tests in healthy capuchin monkeys (Cebus apella) with the aim of establishing normal physiological reference values for this species. METHODS: A total of 15 healthy, capuchin monkeys were used to test most of the parameters in this investigation. Five of the 15 monkeys were used for the evaluation of normal conjunctival flora. Ages varied from 6 to 20 years of age. Selected diagnostic ocular tests were performed including Schirmer tear test (STT), tonometry using an applanation tonometer (Tonopen), central corneal thickness (CCT) using an ultrasonic pachymeter (Sonomed, Micropach), Model 200P+) and culture of the normal conjunctival bacterial flora. RESULTS AND DISCUSSION: Results for selected ocular diagnostic tests investigated here for the capuchin monkey eye were as follows: IOP: 18.4 +/- 3.8 mmHg; STT: 14.9 +/- 5.1 mm/min; CCT: 0.46 +/- 0.03 mm. No statistically significant differences between ages or genders were found for any of the results. Streptococcus sp. and Corynebacterium sp. were isolated from healthy conjunctival and eyelid margins, suggesting they are normal constituents of the conjunctival flora of the capuchin monkey. The data obtained in this investigation will help veterinary ophthalmologists and laboratory animal medicine specialists to more accurately diagnose ocular diseases in the capuchin monkey. These ophthalmic reference values will be particularly useful to diagnose discrete or unusual pathological changes of the capuchin monkey eye.