Impact of quercetin, carnosine, and ozone in the cryopreservation on Nellore (Bos indicus) semen.

The objective of this study was to reduce the effects of cryoinjury caused in bovine semen by cryopreservation. Ejaculates were collected from Nellore bulls and subjected to freezing in C (control), ozone (15, 30, and 60 µg mL-1 of ozone), quercetin (25, 50, and 100 µg mL-1 of quercetin), and carnosine groups (100, 200, and 300 ng mL-1 of carnosine). Samples were evaluated post-thaw (M0) and post-rapid thermoresistance test (M30) for sperm kinetics (total motility, progressive motility, curvilinear speed, linearity and amplitude of lateral head displacement) and cell structure viability (plasma membrane integrity, acrosomal integrity, mitochondrial potential, membrane fluidity, and lipid peroxidation). There were no differences (P > 0.05) between the control, quercetin, and carnosine-treated groups for the parameters evaluated at M0 and M30. In turn, supplementation with ozone resulted in lower values for sperm kinetics (P < 0.05) and lower mitochondrial potential at M30 (P < 0.05). Quercetin and carnosine at the concentrations used did not promote significant gains in frozen semen, nor did they demonstrate cytotoxicity. We expected to obtain positive results with the use of ozone. Nonetheless, the addition was harmful to the parameters of sperm kinetics, and its effect was not observed as a possible pro-antioxidant. We believe that the fact that the gas did not harm the sperm structure opens avenues for tests with lower dosages, since, by reducing its concentration, we could minimize the damage to sperm kinetics.

Estradiol Priming Potentiates the Kisspeptin-Induced Release of LH in Ovariectomized Cows.

The present study examined whether priming with estradiol benzoate (EB) for 12 h increased both the peak and duration of LH release in response to kisspeptin (KISS1, KP) in cows. In a Latin square design, ovariectomized Nelore cows (n = 8) received: Control, i.m. 4 mL of 0.9% saline; KP, i.m. 4 mg murine KISS1-10; EBKP, i.m. 4 mg KISS1-10 + i.m. 2 mg EB simultaneously; EB12KP, i.m. 4 mg KISS1-10 + i.m. 2 mg EB 12 h before KISS1-10. Concentrations of LH were determined in blood samples obtained at time 0 (treatment), 20, 40, 60, 90, 120, 150, 180, 210 and 270 min. Concentrations of LH were analyzed by Proc GLIMMIX for repeated measures. In case of significance, the adjusted Tukey test was used to test for differences among treatments. GraphPad 8.0 PRISM® was used to determine the area under the LH-response curve (AUC) after injection of KISS1-10. Plasma LH remained relatively constant throughout sampling after treatment with saline. The peak in LH after injection of KISS1-10 occurred at 20 min in Groups KP and EBKP and at 40 min in Group EB12KP. The peak LH response (∆LH, ng/mL) was greater (p < 0.01) in Group EB12KP (5.6 ± 0.9) than in Groups KP (2.4 ± 0.9) and EBKP (3.5 ± 0.9), which did not differ. AUC (LH ng/mL*min) was greater (p = 0.02) in Group EB12KP (439 ± 73) than in Groups KP (176 ± 73) and EBKP (241 ± 73), with the latter two groups not differing. The findings indicated that 12 h priming with EB increased both the peak and duration of the LH response to treatment with KISS1. The incorporation of EB priming and KISS1 could improve the efficiency of estrus synchronization with fixed-time AI in cows. This would have an important practical application in assisted breeding in beef and dairy cattle.

P4/E2-based protocol for synchronisation of ovulation of mares during the breeding and non-breeding season.

Dispersed ovulation at the breeding (BS) and anestrus at non-breeding season (NBS) are major impediments to embryo transfer and insemination programmes. The present study aimed to evaluate a hormonal P4/E2-based synchronisation protocol in mares during both the BS and the NBS on ovarian/follicle behaviour. Mares underwent a hormone protocol to synchronise their ovulation during the BS (n = 8) and NBS (n = 10), starting (D0) with the insertion of an intravaginal device containing 1 g of P4 and 7 mg Estradiol Benzoate IM. (EB). On D9, the device was removed and injected with 0.25 mg of cloprostenol sodic IM and 2 mg of EB IM. Follicular behaviour was evaluated using a daily transrectal ultrasound (24/24 h) from D0 until ovulation. When the dominant follicle (DF) measured at least 35 mm, females were injected with 0.25 mg of gonadorelin acetate IM to induce ovulation. The DF on D0 were similar in animals between BS (18.9 ± 8.4 mm) and NBS (23.7 ± 9.2 mm; p = 0.2700). However, in the BS the DF was smaller (14.2 ± 4.7 mm) on D9 than during NBS (22.0 ± 7.1 mm; p = 0.0177). During the BS, the ovulatory follicle is smaller (p = 0.0042) than during NBS, measured at 33.5 ± 4.6 mm and 41.3 ± 2.8 mm, respectively. Ovulation time after P4 removal was similar during BS (173.1 ± 68.8 h) and NBS (192 ± 58.2 h; p = 0.3507). There was no difference towards an ovulation rate during BS (88%) and NBS (60%; p = 0.0978). There was no difference in spontaneous ovulation during BS (43%) and NBS (0%; p = 0.6085). This hormonal protocol would be an effective tool for inducing cyclicity/ovulation in mares during BS and NBS.

Shading effect on physiological parameters and in vitro embryo production of tropical adapted Nellore heifers in integrated crop-livestock-forest systems.

The aim of this study was to evaluate the impact of increased shadow supply in integrated crop-livestock-forest systems on in vitro embryonic development and physiological parameters related to stress response in Nellore heifers (Bos indicus). For the study, animals (n = 16) were randomly divided into two groups and kept in areas with different afforestation systems, the integrated crop-livestock-forest (ICLF) and the integrated crop-livestock (ICL) system. The microclimate of the ICLF system provided better comfort conditions than ICL. No differences of respiratory rate, rectal temperature, cortisol, T3, T4, oocyte quality, and cleavage rate between the systems were verified. A higher blastocyst rate was observed in the ICLF (p < 0.05). The results demonstrate that Nellore heifers managed in ICLF during summer in Midwest of Brazil showed higher production of in vitro embryos, without typical changes in its physiological parameters. The results observed in the present study indicate that zebu females are able to respond satisfactorily to the intense heat conditions; however, we believe that the long period to which these animals are exposed to these conditions interferes in the oocyte competence and embryo development.

Genome-wide association study for age at puberty in young Nelore bulls.

Selection for bulls that would reach puberty early reduces the generation interval and increases fertility and herd productivity. Despite its economic importance, there are few QTL associated with age at puberty described in the literature. In this study, a weighted single-step genome-wide association study was performed to detect genomic regions and putative candidate genes related to age at puberty in young Nelore bulls. Several protein-coding genes related to spermatogenesis functions were identified within the genomic regions that explain more than 0.5% of the additive genetic variance for age at puberty in Nelore bulls, such as ADAM11, BRCA1, CSNK2A, CREBBP, MEIOC, NDRG2, NECTIN3, PARP2, PARP9, PRSS21, RAD51C, RNASE4, SLX4, SPA17, TEX14, TIMP2 and TRIP13 gene. Enrichment analysis by DAVID also revealed several GO terms related to spermatogenesis such as DNA replication (GO:0006260), male meiosis I (GO:0007141), double-strand break repair (GO:0006302), base excision repair (GO:0006284), apoptotic process (GO:0006915), cell-cell adhesion (GO: 0098609) and focal adhesion (GO:0005925). The heritability for age at puberty shows that this trait can be improved based on traditional EBV selection. Adding genomic information to the system helps to elucidate genes and molecular mechanisms controlling the sexual precocity and could help to predict sexual precocity in Nelore bulls with greater accuracy at younger age, which would speed up the breeding programme for this breed.

Administration of PGF2α during the periovulatory period increased fertilization rate in superovulated buffaloes.

The aim of the present study was to determine the recovery of embryonic structures (ova/embryos) and fertilization rate in superovulated buffaloes treated with PGF2α during the periovulatory period. On day 0 (D0), buffaloes at random stages of the estrous cycle were treated with an intravaginal progesterone device (P4; 1.0 g) and estradiol benzoate (EB, 2.0 mg i.m.). From D4 to D7, all buffaloes received i.m. FSH (200 mg total) twice-daily over 4 days in decreasing doses. On D6 and D7, the animals were given PGF2α analogue (0.53 mg i.m. sodium cloprostenol) and the P4 device was removed on D7. On D8, all buffaloes received GnRH (20 µg i.m. buserelin acetate). Buffaloes were then randomly allocated to one of three groups: control (Group C, n = 18), no further treatment; PGF2α analogue injection (Group IM-PGF; n = 18), four injections (0.53 mg i.m. sodium cloprostenol) 12 h apart, from D8 to D10; PGF2α analogue osmotic pump (Group OP-PGF; n = 18), s.c. osmotic mini-pump (2.12 mg sodium cloprostenol) from D8 to D10. The study had a crossover design (three treatments x three replicates). All animals underwent timed AI, 12 and 24 h after treatment with GnRH. Embryonic structures were recovered on D14. Ovarian ultrasonography was used on D8 and D14 to record follicular superstimulation and superovulatory responses. Blood samples were obtained on Days 7, 8, 9 and 10 to measure circulating concentrations of P4, E2 and PGFM. Data were analyzed by GLIMMIX procedure of SAS®. There was no effect (P = 0.58) of treatment on the total number of embryonic structures (Group C, 2.1 ±â€¯0.8; Group IM-PGF, 2.1 ±â€¯0.6; Group OP-PGF, 1.4 ±â€¯0.4). There was also no effect (P = 0.93) of treatment on the recovery rate of embryonic structures (oocytes and embryos D14/CL D14). The fertilization rate was higher (P = 0.04) in Groups IM-PGF (84.6%) and OP-PGF (88.0%), which did not differ, than Group C (63.2%). The viable embryos rate was greater (P < 0.01) for Groups IM-PGF (82.0%) and OP-PGF (88.0%) than Group C (52.6%). There was no interaction between treatment and time and treatment effects for P4, E2 and PGFM concentrations. The findings showed that treatment with PGF2α during the periovulatory period has potential to increase fertilization rate and embryo production in superovulated buffaloes.

Vitrification of germinal-vesicle stage equine oocytes: Effect of cryoprotectant exposure time on in-vitro embryo production.

Previous studies have found low rates of blastocyst development (0-11%) after vitrification of germinal vesicle (GV)-stage equine oocytes. In this study, we systematically evaluated a short (non-equilibrating) system for GV-stage oocyte vitrification. In Exp. 1, we assessed oocyte volume in cumulus-oocyte complexes (COCs) exposed to components of a short protocol, using 2% each of ethylene glycol and propylene glycol in the first solution (VS1); 17.5% of each plus 0.3 M trehalose in the second solution (VS2); and fetal bovine serum as the base medium. Based on the time to oocyte minimum volume, we selected a 40-sec exposure to VS1. In Exp. 2, we evaluated exposure times to VS2 and, based on rates of subsequent maturation in vitro, we selected 65 s. In Exp. 3, we used the optimized vitrification system (40-VS1; 65-VS2) and evaluated three warming procedures. Blastocyst development after ICSI was equivalent (15%) for COCs warmed in either standard (trehalose stepwise dilution) or isotonic (base medium) solutions, but was reduced (0%) for COCs warmed in a highly hypertonic (1.5 M trehalose) solution. Exposure to the vitrification and warming solutions, without actual vitrification, was associated with reduced blastocyst development (0-5%; Exp. 4). We conclude that this optimized short protocol supports moderate blastocyst production after vitrification of GV-stage equine COCs. Oocytes can be warmed in isotonic medium, which simplifies the procedure. The systems used still showed a high level of toxicity and further work is needed on both vitrification and warming methods to increase the efficiency of this technique.

Utilização de diferentes volumes de sêmen na realização do teste hiposmótico em touros adultos da raça nelore / Use of different semen volumes in hypoosmotic test of adult nelore bulls / El uso de diferentes volúmenes de semen en el test hiposmótico en toros adultos de la raza nelore

O objetivo deste estudo foi avaliar diferentes proporções de sêmen: solução hiposmótica na realização do teste hiposmótico e suas relações com a congelabilidade do sêmen de touros zebuínos. Utilizaram-se 15 ejaculados de três touros adultos da raça Nelore. No sêmen in natura realizou-se a avaliação física e morfológica, a coloração supravital e o teste hiposmótico. No teste hiposmótico foi utilizada uma solução com osmolaridade de 100 mOsm/Kg com 15 minutos de período de incubação a 37 ºC, tanto no sêmen in natura quanto no congelado/descongelado. Foram utilizados quatro volumes de sêmen em 1mL de solução hiposmótica: 10, 20, 50 e 100 µL. As amostras criopreservadas foram descongeladas e foram realizados os testes hiposmótico, coloração supravital, teste de termo-resistência lento e a coloração fluorescente. Os valores médios e desvios padrão do percentual de espermatozoides reativos ao teste hiposmótico em sêmen in natura e congelado/descongelado foram 69,3 ± 11,8 e 20,5 ± 6,8; respectivamente. Não houve correlação do teste hiposmótico com os aspectos físicos e morfológicos e os testes complementares realizados em sêmen in natura e congelado/descongelado. Nenhum teste de integridade de membrana plasmática dos espermatozoides foi capaz de classificar os touros quanto a sua congelabilidade do sêmen. Conclui-se que o teste hiposmótico pode ser realizado com 20 a 100 µL de sêmen in natura, e 10 a 100 µL de sêmen congelado/descongelado em 1 mL de solução hiposmótica, sem interferir em seus resultados, mas deve-se optar por 100 µL tanto para sêmen in natura e congelado/descongelado, porque melhora consideravelmente a leitura das lâminas.(AU)

The objective of this study was to evaluate different proportions of semen: hypoosmotic solution in the hypoosmotic swelling test and their relationship with semen freezability in Zebu bulls. A total of 15 ejaculates from three adult Nelore bulls were used. Physical and morphological features were analyzed in fresh semen, as well as supravital staining and hypoosmotic swelling test. In the hypoosmotic test, a hypoosmotic solution with 100 mOsm/kg osmolality using 15 minutes incubation at 37 °C was used both in fresh and frozen/thawed semen. Four semen volumes in 1-ml hyposmotic solution were used: 10, 20, 50 and 100 µL. Cryopreserved samples were thawed and submitted to hypoosmotic tests, supravital staining, slow thermo-resistance test and fluorescent staining. Mean values and standard deviations of the percentage of reactive sperm cells in the hypoosmotic test in fresh and frozen/thawed semen were 69.3 ± 11.8 and 20.5 ± 6.8, respectively. There was no correlation between the hypoosmotic test and physical and morphological features and the complementary tests performed on fresh and frozen/thawed semen. None of the plasma membrane integrity tests was able to predict bull semen freezability. It can be concluded that the hypoosmotic test can be performed with 20 to 100 µL fresh semen, and 10 to 100 µL of frozen/thawed semen in 1 mL of hypoosmotic solution without interfering with their results, but 100 µL should be used in both, because it considerably improves the view of the slides.(AU)

El objetivo de este estudio ha sido evaluar diferentes proporciones de semen: solución hiposmótica en la realización del test hiposmótico y sus relaciones con la congelabilidad del semen de toros cebú. Se utilizaron 15 eyaculados de tres toros adultos de la raza Nelore. En el semen fresco se realizó evaluación física y morfológica, la tinción supravital y test hiposmótico. En el test hiposmótico se ha utilizado una solución con osmolaridad de 100 mOsm/kg con un período de incubación de 15 minutos a 37 ºC, tanto en el semen fresco cuanto en el congelado/descongelado. Fueron utilizados cuatro volúmenes de 1 mL de solución hiposmótica: 10, 20, 50, y 100 µL. Las muestras criopreservadas fueron descongeladas y realizados los tests hiposmótico, tinción supravital, test de resistencia al fuego lento y la tinción fluorescente. Los valores medios y desvío estándar del porcentaje de espermatozoides reactivos al test hiposmótico en l semen fresco y congelado/descongelado fueron 69,3 ± 11,8 y 20,5 ± 6,8; respectivamente. No hubo correlación del test hiposmótico con las características físicas y morfológicas y pruebas adicionales en el semen fresco y congelado/descongelado. Ningún test de integridad de la membrana plasmática de los espermatozoides han sido capaz de clasificar a los toros cuanto su congelabilidad del semen. Se puede concluir que el test hiposmótico puede ser realizado con 20 a 100 µL de semen fresco, y de 10 a 100 µL de semen congelado/descongelado en 1 mL de solución hiposmótica, sin interferir en sus resultados, pero se debe optar por 100 µL para el semen fresco y congelado/descongelado, porque mejora significativamente la lectura de las láminas.(AU)

Uso de colesterol na criopreservação espermática e fertilidade: uma revisão / Use of cholesterol in sperm cryopreservation and fertility: a review / Uso de colesterol en la criopreservación espermática y fertilidad: una revisión

A criopreservação é um método amplamente utilizado para o armazenamento de células espermáticas em longo prazo. Essa técnica facilita a difusão e a disponibilidade de material genético a ser utilizado tanto na produção in vitro (PIV) como na inseminação artificial, biotecnologia aplicada na maioria das espécies domésticas. Pesquisas têm desenvolvido estratégias para otimizar a utilização do sêmen por meio da redução das injúrias ocorridas durante o processo de criopreservação, e vem conseguindo melhorar os parâmetros espermáticos pós-descongelação com a adição de ciclodextrina carregada com colesterol (CCC) ao sêmen puro ou previamente diluído das diferentes espécies estudadas. Apesar dos resultados promissores, melhor fertilidade do sêmen tratado com CCC tem sido demonstrada somente in vitro, enquanto que in vivo os resultados ainda não são compensatórios, necessitando maiores investigações para tornar viável a aplicação comercial dessa técnica. O objetivo dessa revisão foi compilar alguns resultados dos principais pesquisadores na área, expondo o estado atual e as perspectivas para melhorias da fertilidade do sêmen tratado com CCC...

Cryopreservation is a method widely used for the long-term storage of sperm cells. This technique facilitates the dissemination and availability of genetic material to be used in both in vitro production (IVP) and in artificial insemination, the biotechnology applied to most domestic species. Research has developed strategies to optimize the use of semen through the reduction of injuries occurred during the cryopreservation process, having succeeded in improving post-thaw sperm parameters with the addition of cholesterol-loaded cyclodextrin (CLC) to pure or previously diluted semen samples from the different species studied. Despite the promising results, better fertility of semen treated with CLC has only been demonstrated in vitro, while in vivo results are not yet feasible, requiring further investigation to result in viable commercial application of such technique. The objective of this review is to compile a few results from the leading researchers in the area, exhibiting the current state and prospects for improving the fertility of semen treated with CLC...

La criopreservación es un método ampliamente utilizado para el almacenamiento de células espermáticas a largo plazo. Esa técnica facilita la difusión y la disponibilidad de material genético a ser utilizado tanto en la producción in vitro (PIV) como en la inseminación artificial, biotecnología aplicada en la mayoría de las especies domesticas. Investigaciones han desarrollado estrategias para perfeccionar la utilización del semen por medio de la reducción de las injurias ocurridas durante el proceso de criopreservación, y ha conseguido mejorar los parámetros espermáticos pos descongelamiento con la adición de ciclodextrina cargada con colesterol (CCC) al semen puro o previamente diluido. A pesar de los resultados promisores, mejor fertilidad del semen tratado con CCC ha sido demostrado solo in vitro, mientras que in vivo los resultados todavía no son compensatorios, necesitando de mayores investigaciones para volver viable la aplicación comercial de esa técnica. El objetivo de esa revisión ha sido compilar algunos resultados de los principales investigadores del área, exponiendo el estado actual y las perspectivas para mejorías de la fertilidad del semen tratado con CCC...

Estresse por calor: alterações na fisiologia reprodutiva e estratégias para amenizar seus efeitos negativos na fertilidade de fêmeas bovinas / Heat stress: alterations on reproductive physiology and strategies to mitigate the negative effects fertility of bovine females / Estrés por calor: cambios en la fisiología reproductiva y estrategias para amenizar sus efectos negativos en la fertilidad de hembras bovinas

O estresse por calor, comum em clima tropical, vem sendo considerado um dos principais fatores de falha reprodutiva de fêmeas bovinas, incluindo danos ao desenvolvimento e maturação oocitária, desenvolvimento embrionário inicial e fetal, lactação e endocrinologia reprodutiva. Para tentar minimizar tais prejuízos, é necessário melhor entendimento da influência térmica sobre os processos reprodutivos a fim de aperfeiçoar o manejo para aumentar a fertilidade. Esta revisão tem como objetivo buscar o melhor entendimento de como e quando o estresse por calor afeta a reprodução de bovinos, no intuito de se desenvolver estratégias visando melhorar a fertilidade em ambientes de elevadas temperatura.

The heat stress, common in tropical climates, has been considered one of the major factor in reproductive failure in cows, including damages in the oocyte development and maturations, early embryo and fetus development, lactations and reproductive endocrinology. The genetic adaptation to heat stress is possible not only in relation to the body temperature regulation, but also at cellular resistance level. To try to minimize these problems, a better understanding of the thermal influence on the reproductive processes is necessary, with the aim of improving the reproductive management. This review aims to offer a better understanding of how and when the heat stress affects reproductive function of bovines, in order to develop strategies to increase fertility in environments with high thermal loads.

El estrés por calor, común en climas tropicales, ha sido considerado uno de los principales factores de fracaso reproductivo en hembras bovinas, incluyendo daños al desarrollo y maduración oocitaria, desarrollo embrionario inicial y fetal, lactancia y endocrinología reproductiva. Para intentar minimizar estos problemas, es necesario entender mejor la influencia térmica en los procesos reproductivos, con el fin de perfeccionar el manejo para aumentar la fertilidad. Esta revisión tiene como objetivo buscar mejor comprensión de cómo y cuándo el estrés por calor afecta la reproducción del ganado, buscando desarrollar estrategias para mejorar la fertilidad en entornos de elevadas temperatura.

Human-animal interaction, stress, and embryo production in Bos indicus embryo donors under tropical conditions.

This study investigated the effect of human-animal interaction (HAI) and the stress response on the quality of embryo production in superovulated Nelore (Bos indicus) cattle, under tropical conditions. Thirty-two females underwent a superovulation protocol for 5 days. Cortisol concentrations were determined in blood plasma collected on days 0, 4, and 5. Artificial insemination was performed on days 4 and 5, and nonsurgical embryo flushing on day 11. Embryo production and viability were determined. Human stimulation, animal behaviors, accidents, and handling time were recorded to assess HAI. Cattle age was negatively correlated with accidents, frequency of aversive behaviors, and negative stimuli by stockperson during transit through corral compartments to receive superovulation treatments. The factor analysis revealed two distinct groups. The first group was called stressed and had higher cortisol concentration than the nonstressed group, 16.0 ± 2.1 and 12.5 ± 1.0 ng/mL, respectively. Comparisons between these groups showed that the frequency of voice emissions by the stockperson and the number of accidents were higher in the stressed group, and also, the mean handling time was longer in the stressed group than for the nonstressed. As a result, viability rate of the embryos was 19% lower in the stressed group (P < 0.05). This indicates that intensive negative HAI is likely related to stress, which affects embryo production in a superovulation program.

Evaluation of two regional anesthetic methods on the front limb of dogs using hyperbaric bupivacaine / Avaliação de dois métodos de bloqueios anestésicos regionais no membro anterior em cães usando bupivacaína hiperbárica

PURPOSE: To evaluate the effects of bupivacaine 0.5 and 0.25 percent in intravenous regional anesthesia (IVRA) and brachial plexus block (BPB), respectively, on anesthesia, motor block and cardiovascular parameters in dogs. METHODS: Fourteen healthy adult dogs averaging 10 kilograms (kg) of body weight. Animals were randomly assigned to receive one of the two treatments IVRA (n=7) or BPB (n=7). All the animals were sedated with acepromazine (0.1 mg/kg intramuscular). To execute the BPB was used an electrical nerve stimulation. Anesthesia, motor block, sedation, cardiovascular and respiratory effects were measured as effect of the treatment. RESULTS: BPA showed superior efficiency and duration of anesthesia (BPB - 456 ± 94 minutes vs IVRA - 138 ± 44) as well as motor block. There only physiologic parameter which change were the systolic pressure in BPB and respiratory rate for both treatments. CONCLUSION: In dogs the 0.25 percent hyperbaric bupivacaine in BPB produces a front limb anesthesia about three times more than the 0.5 percent in IVRA, with ptosis of the limb blocked and little interference in the cardiovascular system but with decrease in respiratory rate.

OBJETIVO: Avaliar os efeitos da bupivacaína 0,5 e 0,25 por cento na anestesia regional endovenosa (IVRA) e no bloqueio do plexo braquial (BPB) respectivamente, na anestesia, bloqueio motor e parâmetros cardiovasculares em cães. MÉTODOS: Foram utilizados 14 cães sadios adultos pesando em média 10 kilos. Animais foram aleatoriamente designados a um de dois tratamentos IVRA (n = 7) ou BPB (n = 7). Todos os animais foram sedados com acepromazina (0,1 mg/kg intramuscular). Para realizar o BPB foi usado um estimulador elétrico nervoso. Anestesia, bloqueio motor, sedação, efeitos cardiovascular e respiratório foram mensurados como efeitos dos respectivos bloqueios. RESULTADOS: O bloqueio BPB demonstrou eficiência superior e maior duração da anestesia (BPB - 456 ± 94 minutos vs IVRA - 138 ± 44 minutos) bem como maior envolvimento motor. Somente a pressão arterial sistólica foi alterada no grupo BPB e a freqüência respiratória em ambos os tratamentos. CONCLUSÃO: Em cães, a bupivacaína 0,25 por cento hiperbárica no grupo BPB produziu uma anestesia do membro anterior três vezes mais longa que a 0,5 por cento no grupo IVRA, com ptose do membro bloqueado e pequena interferência no sistema cardiovascular e com diminuição da freqüência respiratória.

Evaluation of two regional anesthetic methods on the front limb of dogs using hyperbaric bupivacaine.

PURPOSE: To evaluate the effects of bupivacaine 0.5 and 0.25% in intravenous regional anesthesia (IVRA) and brachial plexus block (BPB), respectively, on anesthesia, motor block and cardiovascular parameters in dogs. METHODS: Fourteen healthy adult dogs averaging 10 kilograms (kg) of body weight. Animals were randomly assigned to receive one of the two treatments IVRA (n=7) or BPB (n=7). All the animals were sedated with acepromazine (0.1 mg/kg intramuscular). To execute the BPB was used an electrical nerve stimulation. Anesthesia, motor block, sedation, cardiovascular and respiratory effects were measured as effect of the treatment. RESULTS: BPA showed superior efficiency and duration of anesthesia (BPB - 456 +/- 94 minutes vs IVRA - 138 +/- 44) as well as motor block. There only physiologic parameter which change were the systolic pressure in BPB and respiratory rate for both treatments. CONCLUSION: In dogs the 0.25 % hyperbaric bupivacaine in BPB produces a front limb anesthesia about three times more than the 0.5 % in IVRA, with ptosis of the limb blocked and little interference in the cardiovascular system but with decrease in respiratory rate.