Establishing a safe anesthesia concentration window for Nile tilapia (Oreochromis niloticus) (Linnaeus 1758) by monitoring cardiac activity in eugenol immersion baths.

Nile tilapia, Oreochromis niloticus, is the most cultivated fish species in the world, due to its low cost, high growth rate, environmental adaptability, and resistance to disease and stress. Anesthetics for fish become necessary in management because they minimize mortality during transport and maintenance of ponds, one of the most used anesthetics is clove oil, which has eugenol as the major substance, representing 90-95 % of clove oil. The present study evaluates the effect of eugenol on cardiac activity in Oreochromis niloticus specimens and relates it to behavioral data to determine a concentration window for safe anesthesia. For the comportamental analysis, was used five treatments (50, 75, 100, 125, and 150 µL·L-1) were evaluated and for the eletrocardiographic test was used seven groups (Control, Vehicle, 50, 75, 100, 125, and 150 µL·L-1), n = 9/treatment, totaling 108 animals. Behavioral and electrocardiographic tests were performed on all treatments during induction and recovery. The results of the behavioral tests demonstrated the reversibility of the effects with recovery of the posture reflex, varying according to the concentration. The ECG results showed a slow recovery because, at concentrations above 100 µL·L-1, there was no full reversibility of the cardiac effects in the observed experiment time, which could cause greater changes in the tilapia hemodynamics, which led us to identify a window for safe anesthesia. Eugenol is an effective anesthetic in Nile tilapia juveniles when used in concentrations ranging from 50 to 100 µL·L-1, if there is a need for anesthetic deepening, doses above 100 µL·L-1, however, the animals must be monitored due to hemodynamic changes.

Successful Treatment of a Cervical Injury and Myopathy Using Integrative Medicine Techniques in an Eclectus Parrot (Eclectus roratus) Following Cervical Entrapment.

A 2-year-old female eclectus parrot (Eclectus roratus) was presented for suspected cervical myopathy due to trauma. Severe ventroflexion of the cervical spine and mental depression were identified during the physical examination. The bird was responsive to stimuli but otherwise quiet. Plasma biochemistry results were suggestive of a myopathy, based on marked elevations of both aspartate transaminase (25 652 U/L) and creatine kinase (253 240 U/L). Whole-body radiographic images were unremarkable. Treatment was initiated with supportive therapy for presumptive shock, dehydration, pain, myopathy, and possible spinal swelling. Allopathic therapy included subcutaneous fluids; vitamins A, D, and E; dexamethasone sodium phosphate; hydromorphone; and gavage feeding to treat the acute inflammatory process and provide nutritional support during healing. Supportive care through the Integrative Medicine Department (Louisiana State University, Baton Rouge, LA, USA) was also performed on the patient. Photobiomodulation, acupuncture, Tui-na massage, and rehabilitation exercises were instituted to provide adjunct treatment for relieving pain, promoting muscle healing, improving patient demeanor, and improving cervical mobility. Integrative therapies were well tolerated by the patient, with no sedation required. By day 3, mentation had subjectively improved by 50% despite the persistent cervical ventroflexion. By day 8, the elevated serum enzyme activities had decreased, the patient could eat and drink on its own, and it could readily step up and seek attention during handling. The bird was able to lift its head and could hold it at approximately 50% of normal posture. Integrative therapies were continued throughout hospitalization. The bird was released from the hospital 20 days after initial intake, with head carriage in approximately 80% of the expected normal position and no apparent cervical pain based on palpation. This case demonstrates the benefits of integrative therapies as an adjunct treatment for cervical pain and myopathy in a psittacine species.

Histopathological, immunohistochemical and biochemical evaluation of electroacupuncture treatment of nervus radialis and nervus ulnaris injuries in rabbits.

The aim of this study was to evaluate the efficacy of electroacupuncture in acute and chronic phases of radial and ulnar nerve injuries in histopathological, immunohistochemical and biochemical aspects. In the study, the rabbits were divided into four groups namely acute nerve injury (ANI) group, chronic nerve injury (CNI) group, positive control (PC) group and negative control (NC) group. In the ANI, CNI and PC groups, damage was created on the nervus radialis and nervus ulnaris by applying pressure for 60 seconds using a hemostatic forceps under anesthesia. No damage was created in the NC group. Fifteen sessions of electroacupuncture were applied to the rabbits in the ANI, CNI, and NC groups every other day using LI-4 (Large Intestine Meridian-4, He Gu), LI-10 (Large Intestine Meridian-10, Shou San Li), LR-3 (Liver Meridian-3, Tai Chong), and ST-36 (Stomach Meridian-36, Zusanli) electroacupuncture points. Electroacupuncture was not applied to the rabbits in the PC group. Decapitation was performed under general anesthesia at the end of electroacupuncture applications. After the euthanasia procedure, the samples obtained were evaluated for histopathological, immunohistochemical and biochemical parameters. In conclusion, degenerative foci in the treatment groups were found to be fewer than in the PC group whereas NGF and S-100 immunoreactivity were higher in the treatment groups than in the PC group. Whereas no statistically significant difference was observed between the treatment groups and the NC group in terms of oxidative stress factors, there was a statistically significant difference between the treatment groups and the PC group. In light of all these data, we have concluded that electroacupuncture is an effective treatment method for peripheral nerve injuries.

Analysis of teaching methods in anaesthesia in the undergraduate curriculum of four veterinary universities.

OBJECTIVE: To design a holistic audit tool to assess the effectiveness of anaesthesia teaching strategies, and thereby to study veterinary undergraduate teaching methods in different geographical areas. STUDY DESIGN: Qualitative study using interviews of university staff and students to identify common themes and differences in teaching veterinary anaesthesia. METHODS: An audit was performed using an audit tool in four veterinary universities (École Nationale Vétérinaire d'Alfort, France; Royal Veterinary College, UK; University of Buenos Aires, Argentina; and Alma mater studiorum - Università di Bologna, Italy). First, an open-question interview of anaesthesia head of service (60-90 minutes) identified the pedagogical strategies in order to conceive a subsequent semi-directive interview formulated as a SWOT analysis (Strength/Weaknesses/Opportunity/Threats). Second, the SWOT reflection was conducted by a second staff member and focussed on: 1) general organization; 2) topics for pre-rotation teaching; 3) teaching methods for clinical rotation; and 4) assessment methods. Qualitative analysis of the interview responses was performed with semi-structured interviews. Finally, the students evaluated their teaching through a students' questionnaire generated from the output of both interviews. RESULTS: A group of nine lecturers and 106 students participated in the study at four different sites. Preclinical teaching ranged from 13 to 24 hours (median 15 hours). Clinical teaching ranged from 4 to 80 hours (median 60 hours). Overall, all faculties perceived time as a limitation and attempted to design strategies to achieve the curriculum expectations and optimize teaching using more time-efficient exercises. Large animal anaesthesia teaching was found to be a common area of weakness. Internal feedback was delivered to each university, whereas generalized results were shared globally. CONCLUSIONS: This preliminary study proved the generalizability of the protocol used. Recruiting a larger pool of universities would help to identify and promote efficient teaching strategies and innovations for training competent new graduates in an ever-expanding curriculum.

Clove Oil and AQUI-S Efficacy for Zebrafish Embryo, Larva, and Adult Anesthesia.

Since the use of the zebrafish Danio rerio genetic model organism within the scientific research community continues to grow rapidly, continued procedural refinement to support high-quality, reproducible research and improve animal welfare remains an important focus. As such, anesthesia remains one of the most frequent procedures conducted. Here, we compared the effectiveness of clove oil (active ingredient eugenol) and AQUI-S (active ingredient iso-eugenol) with the currently most commonly used tricaine/MS-222 (ethyl 3-aminobenzoate methanesulfonate) and benzocaine anesthesia. We focused on embryos (1 day postfertilization), larvae (5 days postfertilization), and adults (9-11 months) and for the first time used exposure times that are the most relevant in research settings by using zebrafish as a genetic model system. For each age, tricaine and benzocaine achieved the most reproducible, robust anesthesia with the quickest induction and recovery. For some experimental procedures, specific clove oil concentrations in embryos and larvae may represent suitable alternatives. Although different aquatic species at specific ages respond differentially to these agents, the systematic study of comparable effective dosages for procedures most commonly employed represent an important step toward refinement.

Involvement of HPI-axis in anesthesia with Lippia alba essential oil citral and linalool chemotypes: gene expression in the secondary responses in silver catfish.

In teleost fish, stress initiates a hormone cascade along the hypothalamus-pituitary-interrenal (HPI) axis to provoke several physiological reactions in order to maintain homeostasis. In aquaculture, a number of factors induce stress in fish, such as handling and transport, and in order to reduce the consequences of this, the use of anesthetics has been an interesting alternative. Essential oil (EO) of Lippia alba is considered to be a good anesthetic; however, its distinct chemotypes have different side effects. Therefore, the present study aimed to investigate, in detail, the expression of genes involved with the HPI axis and the effects of anesthesia with the EOs of two chemotypes of L. alba (citral EO-C and linalool EO-L) on this expression in silver catfish, Rhamdia quelen. Anesthesia with the EO-C is stressful for silver catfish because there was an upregulation of the genes directly related to stress: slc6a2, crh, hsd20b, hspa12a, and hsp90. In this study, it was also possible to observe the importance of the hsd11b2 gene in the response to stress by handling. The use of EO-C as anesthetics for fish is not recommended, but, the use of OE-L is indicated for silver catfish as it does not cause major changes in the HPI axis.

Basil, tea tree and clove essential oils as analgesics and anaesthetics in Amphiprion clarkii (Bennett, 1830) / Óleos essenciais de manjericão, melaleuca e cravo como anestésicos e analgésicos em Amphiprion clarkii (Bennett, 1830)

Abstract In this study were evaluated the anaesthesia and analgesic effects of clove Eugenia caryophyllata, tea tree Melaleuca alternifolia and basil Ocimum basilicum essential oils (EO) during handling of yellowtail clownfish Amphiprion clarkii. Juveniles (3.70 ± 0.75 cm and 1.03 ± 0.50 g; mean ± standard deviation) were submitted to concentrations of 40, 50, 60, 70 and 80 µl L-1 of clove, 150, 200, 250, 300 and 350 µl L-1 of basil and 200, 300, 400, 500 and 600 µl L-1 of tea tree oils (n=10/concentration), previously defined in pilot tests. Individually and only once, fish from each treatment were placed in a glass recipient containing 1 L of seawater at a temperature of 25 °C, salinity of 35 g L-1 and the specific concentration of diluted EO (stock solution). Control (only seawater) and blank (seawater and ethanol at the highest concentration used to dilute the oils) treatments were also conducted. After reaching the stage of surgical anaesthesia, fish were submitted to biometry and a sensibility test. After that, they were transferred to clean seawater for anaesthesia recovery. The times of induction needed to reach each anaesthesia stage and anaesthesia recovery were recorded. Animals were observed for 72 hours after the procedures. All the EO provoked anaesthesia and analgesic effects in A. clarkii, but basil oil is not recommended because it caused involuntary muscle contractions and mortality in 100% and 12% of fish, respectively. The lower concentrations that promote suitable induction and recovery times are 50 µl L-1 of clove oil and 500 µl L-1 of tea tree oil. However, due to its complementary high analgesic efficiency, clove oil is recommended as the ideal anaesthetic for A. clarkii.

Resumo Neste estudo foram avaliados os efeitos anestésicos e analgésicos dos óleos essenciais (OE) de cravo Eugenia caryophyllata, melaleuca Melaleuca alternifolia e manjericão Ocimum basilicum durante manejo de peixes-palhaços Amphiprion clarkii. Juvenis (3.70 ± 0.75 cm e 1.03 ± 0.50 g; média ± desvio padrão) foram submetidos às concentrações de 40, 50, 60, 70 e 80 µl L-1 de cravo, 150, 200, 250, 300 e 350 µl L-1 de manjericão e 200, 300, 400, 500 e 600 µl L-1 de melaleuca (n=10/concentração), previamente definidas em testes pilotos. Individualmente e somente uma vez, os peixes de cada tratamento foram colocados em recipiente de vidro contendo 1 L de água salgada, em temperatura de 25 °C, salinidade de 35 g L-1 e a concentração específica de OE diluída (solução estoque). Tratamentos controle (apenas água marinha) e branco (água marinha e a maior concentração de etanol utilizada para diluição dos óleos) também foram conduzidos. Após atingirem o estágio de anestesia cirúrgica, os peixes foram submetidos à biometria e teste de sensibilidade. Em seguida, foram transferidos para água marinha limpa. Os tempos necessários para atingir cada estágio anestésico e recuperação foram registrados. Os animais foram observados por 72 horas após os procedimentos. Todos os OE provocaram anestesia e analgesia em A. clarkii, porém o óleo de manjericão não é recomendado, pois causou contrações musculares involuntárias e mortalidade em 100% e 12% dos animais, respectivamente. As menores concentrações que promovem indução anestésica e recuperação em tempos adequados são 50 µl L-1 de óleo de cravo e 500 µl L-1 de óleo de melaleuca. Entretanto, devido à sua alta eficiência analgésica complementar, o óleo de cravo é recomendado como o anestésico ideal para A. clarkii.

Uso de cetamina pela via cólon-retal para contenção química de jiboias Boa constrictor Linnaeus, 1758 com teste de influência da droga sobre o sistema renal / Use of ketamine by colon-rectal route for chemical restraint in Boa constrictor Linnaeus, 1758 with test of influence of the drug on renal system

Por serem frequentes na clínica de animais silvestres, faz-se necessária a manipulação de jiboias e para isso, indispensável o conhecimento sobre as manobras precisas para o tratamento das possíveis afecções. Quando se opta pela contenção química, ou pela realização de procedimentos cirúrgicos, um dos fármacos utilizados na anestesia de serpentes é a cetamina. Viu-se a necessidade de buscar uma via alternativa, semelhante em eficácia às tradicionais para a contenção química, porém que minimizasse os riscos e efeitos adversos encontrados na sua execução. O presente trabalho sugere que a via retal seja esta alternativa, por isso, treze jiboias foram submetidas à administração de 70mg/kg de cloridrato de cetamina, com sonda uretral, através da cloaca até o cólon-reto. Foram avaliados, nos tempos 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 e 120 minutos, a partir da administração do fármaco, os seguintes parâmetros: frequência cardíaca, relaxamento muscular e mobilidade, resistência à contenção ou manipulação e reação postural de endireitamento. Foi realizada coleta de 0,5mL de sangue por punção do seio venoso paravertebral cervical, antes da administração do fármaco, no dia seguinte e após nove dias. Foram dosadas as concentrações plasmáticas de cálcio, fósforo e ácido úrico de todos os exemplares a fim de verificar o perfil bioquímico renal e avaliar a influência do fármaco neste sistema. Não foram observadas alterações bioquímicas plasmáticas durante o período de avaliação. Foi possível promover a contenção química das jiboias Boa constrictor, utilizando cloridrato de cetamina pela via cólon-retal.(AU)

It is necessary to deal with Boa constrictor snakes because they are frequently treated in wild and exotic animal clinics and the knowledge about the required procedures in the treatment of the possible affections becomes imperative. When the choice for chemical restraint or sedation for surgical procedures is made, one of the drugs used in snakes is ketamine. We believed it was necessary to look for an alternative route of drug administration as effective as the regular ones, but with minimum risks and less adverse effects in its execution. Therefore thirteen snakes were submitted to the administration of 70mg/kg of ketamine hydrochloride, with an urethral tube, through the cloaca into the colon-rectum. After this, they were evaluated during the 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 120 next minutes from the administration time using the following parameters: heart rate, muscle relaxation and mobility, handling or restraint resistance and righting reflex. Blood samples were collected from each snake by cervical paravertebral venous sinus punction, before the drug administration, on the next day and nine days after. Serum concentrations of calcium, phosphorus and uric acid were measured in order to check the renal biochemical profile and the possibility of influence of the drug on this system. It was possible to provoke chemical restraint in Boa constrictor snakes, with ketamine hydrochloride administered by the colon-rectal route.(AU)

Basil, tea tree and clove essential oils as analgesics and anaesthetics in Amphiprion clarkii (Bennett, 1830).

In this study were evaluated the anaesthesia and analgesic effects of clove Eugenia caryophyllata, tea tree Melaleuca alternifolia and basil Ocimum basilicum essential oils (EO) during handling of yellowtail clownfish Amphiprion clarkii. Juveniles (3.70 ± 0.75 cm and 1.03 ± 0.50 g; mean ± standard deviation) were submitted to concentrations of 40, 50, 60, 70 and 80 µl L-1 of clove, 150, 200, 250, 300 and 350 µl L-1 of basil and 200, 300, 400, 500 and 600 µl L-1 of tea tree oils (n=10/concentration), previously defined in pilot tests. Individually and only once, fish from each treatment were placed in a glass recipient containing 1 L of seawater at a temperature of 25 °C, salinity of 35 g L-1 and the specific concentration of diluted EO (stock solution). Control (only seawater) and blank (seawater and ethanol at the highest concentration used to dilute the oils) treatments were also conducted. After reaching the stage of surgical anaesthesia, fish were submitted to biometry and a sensibility test. After that, they were transferred to clean seawater for anaesthesia recovery. The times of induction needed to reach each anaesthesia stage and anaesthesia recovery were recorded. Animals were observed for 72 hours after the procedures. All the EO provoked anaesthesia and analgesic effects in A. clarkii, but basil oil is not recommended because it caused involuntary muscle contractions and mortality in 100% and 12% of fish, respectively. The lower concentrations that promote suitable induction and recovery times are 50 µl L-1 of clove oil and 500 µl L-1 of tea tree oil. However, due to its complementary high analgesic efficiency, clove oil is recommended as the ideal anaesthetic for A. clarkii.

Clove oil induces anaesthesia and blunts muscle contraction power in three Amazon fish species.

Clove oil is used as an anaesthetic for many species of fish worldwide; however, relatively few studies have assessed its effectiveness on Amazon fish species and no compelling evidence has ever been reported on the relaxant properties of this oil for skeletal muscle of fish. Thus, the objective of this study was to evaluate the latencies to deep anaesthesia and recovery, along with the myorelaxant effect of clove oil on three Amazon fish species: cardinal tetra, Paracheirodon axelrodi, banded cichlid, Heros severus and angelfish, Pterophyllum scalare, submitted to short-term anaesthetic baths. Fish were assayed in three groups of 60 fish each and individually anaesthetized in a completely randomized design with six clove oil concentrations using 10 fish/species/concentration. Electromyographic recordings from dorsal muscle were performed during stages of induction and recovery in which nine fish/species/stage were used. Deep anaesthesia was attained for all concentrations tested, and no mortalities were observed throughout the experiments and after a 48-h observation period. Concentration of 90 µL L-1 and above promoted fast deep anaesthesia (< 3 min) and calm recovery in angelfish and cardinal tetra, whereas the concentration of 60 µL L-1 sufficed to quickly anaesthetize banded cichlid. Times to full recovery were not significantly contrasting among species and occurred within appropriate time threshold (< 5 min). Clove oil exerted a conspicuous depression of muscle contraction power, and therefore can be effectively used as a muscle relaxant agent for P. scalare, P. axelrodi, H. severus and potentially, for other fish species.

Comparison of ultrasound- and electrostimulation-guided nerve blocks of brachial plexus in dogs.

OBJECTIVE: To compare the effectiveness of ultrasound- and electrostimulation-guided nerve blocks of the brachial plexus and to determine whether ultrasound guidance is feasible in conscious dogs. STUDY DESIGN: Blinded, crossover, experimental study. ANIMALS: Six clinically healthy adult Beagle dogs. METHODS: The nerves of the brachial plexus of the right thoracic limb were blocked under ultrasound guidance (UNB) in conscious dogs and under electrostimulation guidance (ENB) in anesthetized dogs with bupivacaine (0.4 mL kg-1, 0.25%). Saline (0.4 mL kg-1) was injected in control animals. Sensory nerve blockade was evaluated by scoring cutaneous sensation in targeted nerves. Motor nerve blockade was evaluated based on weight bearing, conscious proprioception and withdrawal reflex scores. Times to execute the technique in UNB and ENB were compared using t tests (p < 0.05). Scores for sensory and motor nerve blockades in each treatment were compared with scores before treatment and with control treatment scores using nonparametric repeated-measures two-way analysis of variance. Time to onset and duration of sensory nerve block were assessed using scores for four sensory nerve functions. A successful sensory nerve block was defined by decreases in scores for these functions. Success rates of nerve blocks were compared among treatments using McNemar's test. RESULTS: In UNB and ENB, onset times of sensory nerve blocks were 1 hour and 1.5 hours, respectively. Onset times of motor nerve blocks were 0.5 hour in both treatments. In UNB and ENB, durations of sensory nerve block were 3 hours and 0.5 hour, respectively, and durations of motor nerve block were 7.5 hours and 6.5 hours, respectively. Success rates did not differ between the techniques. CONCLUSIONS AND CLINICAL RELEVANCE: The UNB brachial plexus block had a shorter onset time and longer duration than ENB. UNB can be performed in conscious dogs or those under mild sedation.

Effects of a mixture of medetomidine, midazolam and butorphanol on anesthesia and blood biochemistry and the antagonizing action of atipamezole in hamsters.

Syrian golden hamsters (Mesocricetus auratus) are useful laboratory rodents for studying human infectious diseases, metabolic diseases and cancer. In other rodents, such as mice and rats, a mixture of medetomidine, midazolam and butorphanol functions as a useful anesthetic, although it alters some blood biochemical parameters. In this study, we examined the effects of this mixture on anesthesia and blood biochemical parameters, and the action of atipamezole, a medetomidine antagonist, in hamsters. Intramuscular injection of a mixture of medetomidine, midazolam and butorphanol at doses of 0.15, 2.0 and 2.5 mg/kg, respectively, had a short induction time (within 5 min) and produced an anesthetic duration of approximately 100 min in hamsters. We also demonstrated that 0.15 mg/kg of atipamezole, corresponding to the same dose as medetomidine, made hamsters recover quickly from anesthesia. The anesthetic agent markedly altered metabolic parameters, such as plasma glucose and insulin; however, 0.15 mg/kg of atipamezole returned these levels to normal range within approximately 10 min after the injection. The anesthetic also slightly altered mineral levels, such as plasma inorganic phosphorus, calcium and sodium; the latter two were also improved by atipamezole. Our results indicated that the mixture of medetomidine, midazolam, and butorphanol at doses of 0.15, 2.0 and 2.5 mg/kg, respectively, functioned as an effective anesthetic, and atipamezole was useful for antagonizing both anesthesia and biochemical alteration in hamsters.

Anesthesia and anesthetic action mechanism of essential oils of Aloysia triphylla and Cymbopogon flexuosus in silver catfish (Rhamdia quelen).

OBJECTIVES: To document the time for anesthesia induction and recovery using different concentrations of essential oils (EOs) of Cymbopogon flexuosus and Aloysia triphylla in silver catfish (Rhamdia quelen), and to determine whether the mechanism of action of either EO involves the benzodiazepine (BDZ) site of the GABAA receptor. STUDY DESIGN: Experimental study. ANIMALS: A total of 144 silver catfish, length 7.5 ± 1.1 cm, weighing 3.95 ± 0.85 g. METHODS: Essential oils were evaluated at concentrations of 25, 150 and 300 µL L-1, and also ethanol alone (seven groups, n = 6 per group). Induction of sedation or anesthesia and recovery were assessed. In a further six groups (n = 6 per group), fish were exposed to both EOs (25, 150 or 300 µL L-1) with diazepam 150 µm, and also diazepam (10 µm) alone. Flumazenil (5 or 10 µm) was added to the recovery water of fish exposed to diazepam (150 µm) or both EOs (150 and 300 µL L-1) (total of 10 groups = 60 fish). RESULTS: Both EOs induced anesthesia at concentrations of 150 and 300 µL L-1, and sedation at 25 µL L-1. There was no significant difference between EOs for reaching deep anesthesia; there was a significantly longer recovery time for the EO of C. flexuosus. The addition of diazepam (150 µm) resulted in faster induction of anesthesia with both EOs, with no significant change in recovery times. Flumazenil (10 µm) reversed the diazepam-induced anesthesia, but not the anesthesia induced by EOs. CONCLUSIONS AND CLINICAL RELEVANCE: The EO of C. flexuosus induced effective sedation (25 µL L-1) and anesthesia (150 and 300 µL L-1) without short-term mortality. The modulation of the BDZ site of the GABAA receptor in the anesthetic action mechanism of both EOs was not demonstrated.

Comparison of Dexmedetomidine-Ketamine with Isoflurane for Anesthesia of Chinchillas (Chinchilla lanigera).

The objective of this study was to compare isoflurane with a combination of dexmedetomidine and ketamine, administered intramuscularly, for anesthesia in chinchillas (Chinchilla lanigera). In a prospective, complete crossover study, adult chinchillas (n = 8; age, 2 to 5 y) were anesthetized with a combination of dexmedetomidine (0.015 mg/kg IM) and ketamine (4 mg/kg IM). Atipamezole (0.15 mg/kg) was injected subcutaneously 45 min after dexmedetomidine-ketamine administration. For comparison, anesthesia also was induced and maintained with isoflurane in 100% oxygen, delivered by facemask. Anesthetic and physiologic parameters were recorded during each anesthesia, including various reflexes, heart rate, respiratory rate, body temperature, and SpO2. Food intake, fecal output, and body weight were recorded daily for 6 d after each anesthetic trial. Induction time, heart rate, respiratory rate, and body temperature did not differ significantly between the 2 anesthetic protocols. Recovery times were shorter and SpO2 was higher in animals that received isoflurane delivered in 100% oxygen. Food intake and fecal output were reduced in the dexmedetomidine-ketamine group for as long as 3 d after anesthesia, whereas isoflurane had no signifcant effect on food intake or fecal output. Both anesthetic protocols provided effective anesthesia in chinchillas. However, when anesthetized with dexmedetomidine-ketamine, chinchillas received room air and became hypoxemic. Future studies are needed to evaluate the effect of oxygen supplementation on anesthetic recovery and on the recovery of food intake and fecal output in chinchillas.

The effects of acupuncture point Pericardium 6 on hydromorphone-induced nausea and vomiting in healthy dogs.

OBJECTIVE: To evaluate the effect of needling at acupuncture point Pericardium 6 on hydromorphone-induced nausea and vomiting. STUDY DESIGN: Randomized controlled clinical study. ANIMALS: Eighty-one mixed-breed, healthy dogs aged 1.8 ± 1.6 years and weighing 14.5 ± 5.6 kg, admitted for elective ovariohysterectomy (n = 75) or castration (n = 6). METHODS: Dogs were randomly assigned to one of three groups: acupuncture at Pericardium 6 (AT, n = 27); alternative acupuncture at Lung 5 (ST, n = 27), and no acupuncture (CT, n = 27). During time 0-30 minutes (baseline), occurrences of hypersalivation, vomiting and licking were recorded. At 30 minutes, subjects were administered hydromorphone (0.1 mg kg(-1) ) in combination with acepromazine (0.03 mg kg(-1) ) intramuscularly. During time 30-45 minutes (post-injection), occurrences of hypersalivation, vomiting and licking were recorded by an observer unaware of group assignment. Groups were compared using a Kruskal-Wallis test followed by a Dunn's post-test, or Fisher's exact tests when appropriate. RESULTS: There were no significant differences in age, weight or baseline observations among groups. Vomiting incidence post-injection was higher in the CT (20/27, 74.1%) and ST (22/27, 81.5%) groups than in the AT (10/27, 37.0%) group (p = 0.0129 and p = 0.002, respectively). The number of vomiting episodes [median (range)] after opioid administration was higher in the ST [1 (1-6)] than the AT [0 (0-2)] group (p = 0.0040). There were no differences in the median number of vomiting episodes between the ST and CT [1 (0-3)] or AT and CT groups. There were no differences in hypersalivation or licking among groups after hydromorphone-acepromazine administration. CONCLUSIONS AND CLINICAL RELEVANCE: Pericardium 6 acupuncture reduced the incidence of hydromorphone-induced vomiting in healthy dogs. This cost-effective technique can improve patient well-being and comfort during the perioperative period.

Blood biochemical changes in mice after administration of a mixture of three anesthetic agents.

Currently, from the viewpoint of animal welfare, anesthesia or analgesia is required during experimental procedures in animals that are likely to cause pain. A part of these anesthetics have been reported to influence a blood biochemical level. It is important for us to understand the effect of the anesthetic on blood biochemistry when we choose the anesthetic agent to be used in experiments. In this study, we examined the blood biochemical changes in mice after administration of a new mixture of three anesthetic agents -medetomidine / midazolam / butorphanol (MMB). We subcutaneously administered two dose combinations of MMB (0.45 / 6 / 7.5 and 0.9 / 12 / 15 mg/kg) in mice, followed by administration of atipamezole, for reversal of anesthetic effects, after 1 hr. Thereafter, blood biochemistry was assessed at 1, 4 and 24 hr after MMB administration. We observed that MMB administration caused a transient increase in blood sugar, inorganic phosphorus, potassium and creatine kinase levels. These, however, returned to the reference range 24 hr after MMB administration. In conclusion, MMB changes the levels of some blood biochemical parameters, but not to an extent that would threaten health. However, when using laboratory animals, this effect of MMB may influence the experimental results, depending on the experimental content. Hence, the choice of anesthetic agents used in laboratory animals should be based on detailed knowledge of their pharmacological effects.

Gabapentin as an adjuvant for postoperative pain management in dogs undergoing mastectomy.

This study aimed to evaluate the analgesic efficacy of gabapentin as an adjuvant for postoperative pain management in dogs. Twenty dogs undergoing mastectomy were randomized to receive perioperative oral placebo or gabapentin (10 mg/kg). All dogs were premedicated with intramuscular acepromazine (0.03 mg/kg) and morphine (0.3 mg/ kg). Anesthesia was induced with propofol (4 mg/kg) intravenously and maintained with isoflurane. Intravenous meloxicam (0.2 mg/kg) was administered preoperatively. Postoperative analgesia was evaluated for 72 hr. Rescue analgesia was provided with intramuscular morphine (0.5 mg/kg). Dogs in the Placebo group received significantly more morphine doses than the Gabapentin group (P=0.021), despite no significant differences in pain scores. Perioperative gabapentin reduced the postoperative morphine requirements in dogs after mastectomy.

S-(+)-Linalool from Lippia alba: sedative and anesthetic for silver catfish (Rhamdia quelen).

OBJECTIVE: The present study describes the isolation of linalool from the essential oil of Lippia alba (Mill.) N. E. Brown, and its anesthetic effect in silver catfish (Rhamdia quelen) in comparison with essential oil. The potentiation of depressant effects of linalool with a benzodiazepine (BDZ) and the involvement of GABAergic system in its antagonism by flumazenil were also evaluated. STUDY DESIGN: Prospective experimental study. ANIMALS: Juvenile silver catfish unknown sex weighing mean 9.24 ± 2.83 g (n = 6 for each experimental group per experiment). METHODS: Column chromatography was used for the isolation of S-(+)-linalool. Fish (n = 6 for each concentration) were transferred to aquaria with linalool (30, 60, and 180 µL L(-1)) or EO of L. alba (50, 100, and 300 µL L(-1)) to determine the induction time for anesthesia. After induction, the animals were transferred to anesthetic-free aquaria to assess their recovery time. To observe the potentiation, fish were exposed to linalool (30, 60, and 180 µL L(-1)) in the presence or absence of BDZ (diazepam 150 µm). In another experiment, fish exposed to linalool (30 and 180 µL L(-1) or BDZ were transferred to an anesthetic-free aquaria containing flumazenil (5 µm) or water to assess recovery time. RESULTS: Linalool had a similar sedation profile to the essential oil at a proportional concentration in silver catfish. However, the anesthesia profile was different. Potentiation of linalool effect occurred only when tested at low concentration. Fish exposed to BDZ showed faster anesthesia recovery in water with flumazenil, but the same did not occur with linalool. CONCLUSIONS AND CLINICAL RELEVANCE: The use of linalool as a sedative and anesthetic for silver catfish was effective at 30 and 180 µL L(-1), respectively. The mechanism of action seems not to involve the benzodiazepine site of the GABAergic system.

Anesthetic activity of the essential oil of Aloysia triphylla and effectiveness in reducing stress during transport of albino and gray strains of silver catfish, Rhamdia quelen.

This study investigated the efficacy of the essential oil (EO) of Aloysia triphylla as an anesthetic for albino and gray strains of silver catfish, Rhamdia quelen. Juveniles were exposed to concentrations between 20 and 800 µL L(-1) EO of A. triphylla to evaluate time of induction and recovery from anesthesia. In another experiment, both strains were divided into four groups such as 0 (control), 30, 40, or 50 µL L(-1) EO and transported for 5 h. The longest time for anesthetic induction and recovery was observed in the albinos. Both strains reached anesthesia in the 100-800 µL L(-1) (11.1-1.24 min) range, without mortality, being 200 µL L(-1) the best response considering time to anesthesia (5.35 min). Albinos transported with all EO concentrations showed higher values of carbon dioxide in the water of transport, but lower levels were observed in grays transported with 40 and 50 µL L(-1) EO when compared to control fish. The same concentrations did not prevent significant whole-body cortisol rise at the end of transport in the albino strain. Juveniles of both strains transported with EO presented lower ion loss to the water compared to control fish. The EO of A. triphylla is an effective anesthetic for albino and gray silver catfish. This EO increases whole-body cortisol levels in the albino strain, but as it reduces net ion loss as in the gray strain, it can be also recommended for transport.

Benzocaine and clove oil as anesthetics for pejerrey (Odontesthes bonariensis) fingerlings / Benzocaina e óleo de cravo como anestésicos para alevinos de peixe-rei (Odontesthes bonariensis)

Pejerrey (Odontesthes bonariensis) is a native species from Rio Grande do Sul, Uruguay and Argentina where it is of great economic importance for artisanal fishing. One difficulty in laboratory research with pejerrey is related to its sensitivity, as it presents higher basal cortisol levels than other freshwater species. For this reason, the aim of this work was to evaluate the efficiency of benzocaine and clove oil as anesthetics for pejerrey fingerlings. Two experiments were done where fingerlings (57±7.8mm and 1.1±0.44g) were exposed to benzocaine with concentrations between 40mgL-1 and 120mgL-1 and to clove oil with concentrations between 12mgL-1 and 75mgL-1. Survival, anesthesia induction time and recovery time for each pharmaceutics were evaluated. Both benzocaine and clove oil pharmaceutics showed efficiency as anesthetics for pejerrey fingerlings, with negative correlation between the dose of anesthetics and the anesthesia induction time. For benzocaine, the concentrations between 80mgL-1 and 100mgL-1 showed better results, as for clove oil the optimal concentrations were between 25mgL-1 and 50mgL-1. On the other hand, the anesthesia recovery time did not present significant variation on the different concentrations of the tested products. The tested products are highly metabolizable by pejerrey.

O peixe-rei (Odontesthes bonariensis) é uma espécie nativa do Rio Grande do Sul, Uruguai e Argentina, onde tem grande importância econômica para a pesca artesanal. Uma dificuldade da pesquisa em laboratório com peixe-rei está relacionada à sua sensibilidade, pois apresenta níveis basais de cortisol mais elevados que outras espécies de água doce. Este trabalho avaliou a eficiência da benzocaína e do óleo de cravo como anestésicos para alevinos de peixe-rei. Foram realizados dois experimentos em que alevinos (57±7,08mm e 1,1±0,44g) foram expostos à concentração entre 40mg-1 e 120mgL-1 de benzocaína e entre 12mgL-1 e 75mgL-1 de óleo de cravo. Avaliaram-se a sobrevivência, o tempo de anestesia e o tempo de recuperação para cada um dos fármacos. Ambos os fármacos, benzocaína e óleo de cravo, mostraram eficiência para anestesiar peixe-rei, com correlação negativa entre a dose e o tempo de indução de anestesia. Para benzocaína, concentrações entre 80mgL-1 e 100mgL-1 mostraram melhor resultado, enquanto para óleo de cravo as melhores concentrações ficaram entre 25mgL-1 e 50mgL-1. Por outro lado, o tempo de recuperação do estado de anestesia não apresentou variação significativa nas diferentes concentrações testadas. O peixe-rei tem elevada capacidade de metabolização dos produtos testados.