Electrocardiographic findings in dogs with obstructive airway diseases / Achados eletrocardiográficos em cães com doenças obstrutivas das vias aéreas

Cardiac rhythm disorders are diagnosed through electrocardiography, which is an important tool to investigate other systemic conditions that may be related to the cardiac conduction system. Cardiac regulation is controlled by the autonomic nervous system, and in dogs, it is mainly modulated by a parasympathetic action exerted by the vagus nerve, called vagal tone. Increased vagal tone can occur physiologically or pathologically, leading to the occurrence of bradyarrhythmias. However, some studies report that airway diseases can exacerbate this tone, together with the reduction of sympathetic pathway activities. This study aimed to analyze the cardiac rhythms in dogs presenting with electrocardiographic alterations related to respiratory diseases, in connection with the exacerbation of vagal tone. Medical records of animals whose diagnoses involved at least one respiratory condition and who underwent electrocardiographic assessment between March 2017 to March 2021 were compiled. Data obtained were compiled in Microsoft Excel®1 spreadsheets and evaluated using descriptive statistics through the BioEstat®2 software. Pearson's correlation was used for quantitative data. A correlation between autonomic regulation and vagal exacerbation was observed in cases with obstructive airways diseases.(AU)

Os distúrbios do ritmo cardíaco são diagnosticados por meio da eletrocardiografia, que é uma importante ferra-menta para investigar outras condições sistêmicas que podem estar relacionadas ao sistema de condução cardíaco. A regulação cardíaca é controlada pelo sistema nervoso autônomo e, em cães, é modulada principalmente pela ação parassimpática exer-cida pelo nervo vago, denominada tônus vagal. O aumento do tônus vagal pode ocorrer fisiologicamente ou patologicamente, levando à ocorrência de bradiarritmias. No entanto, alguns estudos relatam que as doenças das vias aéreas podem exacerbar esse tônus, juntamente com a redução das atividades das vias simpáticas. Este estudo teve como objetivo analisar os ritmos cardíacos em cães com alterações eletrocardiográficas relacionadas a doenças respiratórias, relacionadas à exacerbação do tônus vagal. Foram compilados os prontuários dos animais cujos diagnósticos envolvessem pelo menos uma condição respiratória e que realizaram avaliação eletrocardiográfica, no período entre março de 2017 a março de 2021. Os dados obtidos foram com-pilados em planilhas do Microsoft Excel®1 e avaliados por meio de estatística descritiva por meio do software BioEstat®2. A correlação de Pearson foi usada para dados quantitativos. Foi observada correlação entre regulação autonômica e exacerbação vagal em casos com doenças obstrutivas das vias aéreas.(AU)

Arritmias no uso da dexmedetomina em cães / Arrhythmias in the use of dexmedethine in dogs

A dexmedetomidina é um fármaco agonista a-2 adrenérgico utilizado na anestesiologia veterinária, devido a suas propriedades sedativas e analgésicas. Existem preocupações quanto aos seus efeitos colaterais, principalmente cardiovasculares, dentre eles arritmias. As quais podem comprometer o débito cardíaco e a perfusão tecidual. As arritmias que podem ser observadas com o uso da dexmedetomidina são: bloqueio átrio ventricular de 1º, 2º e 3º grau; arritmia sinusal, e pausa sinusal. Dentre elas a de maior ocorrência é o bloqueio atrioventricular, principalmente o de 2º grau. Essas alterações são dose-dependentes, estudos demonstram que doses de 1 µg /kg podem desencadear a ocorrência de bradiarritmias. O tratamento das arritmias atrioventriculares envolve a administração de anticolinérgicos, antiarrítmicos e no caso de alterações desencadeadas pelo uso da dexmedetomidina a aplicação de um antagonista a-2 adrenérgico. Esta revisão tem como objetivo discorrer sobre as arritmias em cães ocasionadas pelo uso da dexmedetomidina.

Dexmedetomidine is a α-2 adrenergic agonist drug used in veterinary anesthesiologydue to its sedative and analgesic properties. There are concerns about its side effects, especially cardiovascular, among them arrhythmias. These may compromise cardiac output and tissue perfusion. The arrhythmias that may be observed with the use of dexmedetomidine are: ventricularatrium blockade of 1st, 2nd and 3rd degree; sinus arrhythmia, and sinus pause. Among them, the most frequent occurrence is atrioventricular block, especially the second degree. These changes are dose-dependent, studies have shown that doses of 1 μg/kg can trigger the occurrence of bradyarrhythmias. Treatment of atrioventricular arrhythmias involves the administration of anticholinergics, antiarrhythmics and in the case of changes triggered by the use of dexmedetomidinethe application of a α-2 adrenergic antagonist. This review aims to discuss the arrhythmias in dogs caused by the use of dexmedetomidine.

Arritmias no uso da dexmedetomina em cães / Arrhythmias in the use of dexmedethine in dogs

A dexmedetomidina é um fármaco agonista a-2 adrenérgico utilizado na anestesiologia veterinária, devido a suas propriedades sedativas e analgésicas. Existem preocupações quanto aos seus efeitos colaterais, principalmente cardiovasculares, dentre eles arritmias. As quais podem comprometer o débito cardíaco e a perfusão tecidual. As arritmias que podem ser observadas com o uso da dexmedetomidina são: bloqueio átrio ventricular de 1º, 2º e 3º grau; arritmia sinusal, e pausa sinusal. Dentre elas a de maior ocorrência é o bloqueio atrioventricular, principalmente o de 2º grau. Essas alterações são dose-dependentes, estudos demonstram que doses de 1 µg /kg podem desencadear a ocorrência de bradiarritmias. O tratamento das arritmias atrioventriculares envolve a administração de anticolinérgicos, antiarrítmicos e no caso de alterações desencadeadas pelo uso da dexmedetomidina a aplicação de um antagonista a-2 adrenérgico. Esta revisão tem como objetivo discorrer sobre as arritmias em cães ocasionadas pelo uso da dexmedetomidina.(AU)

Dexmedetomidine is a α-2 adrenergic agonist drug used in veterinary anesthesiologydue to its sedative and analgesic properties. There are concerns about its side effects, especially cardiovascular, among them arrhythmias. These may compromise cardiac output and tissue perfusion. The arrhythmias that may be observed with the use of dexmedetomidine are: ventricularatrium blockade of 1st, 2nd and 3rd degree; sinus arrhythmia, and sinus pause. Among them, the most frequent occurrence is atrioventricular block, especially the second degree. These changes are dose-dependent, studies have shown that doses of 1 μg/kg can trigger the occurrence of bradyarrhythmias. Treatment of atrioventricular arrhythmias involves the administration of anticholinergics, antiarrhythmics and in the case of changes triggered by the use of dexmedetomidinethe application of a α-2 adrenergic antagonist. This review aims to discuss the arrhythmias in dogs caused by the use of dexmedetomidine.(AU)

Análise da variabilidade da frequência cardíaca em cordeiros da raça Bergamácia, do nascimento aos 35 dias de idade / Analysis of heart rate variability in Bergamasca newborn lambs from birth at 35th days of age

A atividade do sistema nervoso autônomo sobre o coração pode ser verificada pela variabilidade da frequência cardíaca (VFC), método que quantifica e assim infere sobre a modulação autonômica cardíaca, refletindo o funcionamento do sistema nervoso autônomo. Durante o período neonatal, diferenças significativas no que se refere à maturação autonômica são descritas em diversas espécies. Embora a espécie ovina venha sendo utilizada como modelo experimental em diversos protocolos em neonatologia e cardiologia em humanos, estudos descritivos sobre a VFC utilizando animais saudáveis e não sedados são escassos na literatura. O objetivo do estudo foi descrever a VFC em cordeiros da raça Bergamácia durante os primeiros 35 dias de idade. Foram realizados exames eletrocardiográficos em 20 cordeiros da raça Bergamácia a partir do nascimento e semanalmente até o 35° dia de idade. A VFC foi analisada pelo intervalo RR normal (batimentos sinusais), pela frequência cardíaca, pelo índice de tônus vasovagal (iTVV), pela raiz quadrada da média do quadrado das diferenças entre intervalos RR normais adjacentes (RMSSD) e pela raiz quadrada da somatória do quadrado das diferenças dos valores individuais em relação ao valor médio, dividido pelo número de iR-R em 90 segundos - VFC global (RMSM). Todos os parâmetros se alteraram ao longo das semanas. A frequência cardíaca média elevou-se entre o nascimento e os primeiros sete dias de idade, com decréscimo nas quatro semanas subsequentes, sendo o menor valor encontrado aos 35 dias de idade (145,63±37,80bpm). Entre 21, 28 e 35 dias de idade, o iTVV elevou-se significativamente, o RMSM a partir do 28º dia, e, aos 35 dias, o RMSSD, reflexo da ativação parassimpática, exibiu diferenças em relação aos momentos subsequentes. O início da predominância parassimpática, refletida nos índices da VFC, particularmente o iTVV, ocorre aos 21 dias de idade. A partir dos 35 dias de idade, os índices RMSM e RMSSD podem ser utilizados como marcadores fidedignos das mudanças nos efeitos simpático e parassimpático sobre o coração de cordeiros.(AU)

Autonomic nervous system activity can be checked by heart rate variability (HRV), method that quantifies and thus infers on cardiac autonomic modulation, reflecting the functioning of the autonomic nervous system. During the neonatal period significant differences as regards the autonomic maturation, are described in various species. Although the sheep come being used as experimental model of several protocols in neonatology and cardiology in humans, descriptive studies about the VFC using healthy animals and not sedated are scarce in the literature. The objective of this study was to describe the HRV in the Bergamasca race lambs during the first 35 days of age. Electrocardiographic examinations were performed in 20 lambs of the Bergamasca race from birth, in the7th, 14th, 21st, 28th, and 35th days of age. The HRV was analyzed by normal RR interval (sinus rate), heart rate, index of vagal tone, and the cardiovascular manifestations (square root of the average of the square of the differences between normal RR intervals adjacent). All parameters have changed over the weeks. The average heart rate increased between the birth and the first seven days of age, with decrease in the subsequent four weeks, being the smallest value found at 35 days of age (145.63±37.80bpm). Between 21, 28 and 35 days of age, the iTVV increased significantly, the RMSM from the 28 day, and 35 days, the cardiovascular manifestations, reflex parasympathetic activation, exhibited differences in relation to subsequent times. The beginning of parasympathetic dominance, reflected in the HRV indices, particularly the iTVV, occurs at 21 days of age. From the 35 days of age, the RMSM indices and RMSSD can be used as reliable markers of change in sympathetic and parasympathetic effect on the heart of lambs.(AU)

Análise da variabilidade da frequência cardíaca em cordeiros da raça Bergamácia, do nascimento aos 35 dias de idade / Analysis of heart rate variability in Bergamasca newborn lambs from birth at 35th days of age

Autonomic nervous system activity can be checked by heart rate variability (HRV), method that quantifies and thus infers on cardiac autonomic modulation, reflecting the functioning of the autonomic nervous system. During the neonatal period significant differences as regards the autonomic maturation, are described in various species. Although the sheep come being used as experimental model of several protocols in neonatology and cardiology in humans, descriptive studies about the VFC using healthy animals and not sedated are scarce in the literature. The objective of this study was to describe the HRV in the Bergamasca race lambs during the first 35 days of age. Electrocardiographic examinations were performed in 20 lambs of the Bergamasca race from birth, in the7th, 14th, 21st, 28th, and 35th days of age. The HRV was analyzed by normal RR interval (sinus rate), heart rate, index of vagal tone, and the cardiovascular manifestations (square root of the average of the square of the differences between normal RR intervals adjacent). All parameters have changed over the weeks. The average heart rate increased between the birth and the first seven days of age, with decrease in the subsequent four weeks, being the smallest value found at 35 days of age (145.63±37.80bpm). Between 21, 28 and 35 days of age, the iTVV increased significantly, the RMSM from the 28 day, and 35 days, the cardiovascular manifestations, reflex parasympathetic activation, exhibited differences in relation to subsequent times. The beginning of parasympathetic dominance, reflected in the HRV indices, particularly the iTVV, occurs at 21 days of age. From the 35 days of age, the RMSM indices and RMSSD can be used as reliable markers of change in sympathetic and parasympathetic effect on the heart of lambs.(AU)

A atividade do sistema nervoso autônomo sobre o coração pode ser verificada pela variabilidade da frequência cardíaca (VFC), método que quantifica e assim infere sobre a modulação autonômica cardíaca, refletindo o funcionamento do sistema nervoso autônomo. Durante o período neonatal, diferenças significativas no que se refere à maturação autonômica são descritas em diversas espécies. Embora a espécie ovina venha sendo utilizada como modelo experimental em diversos protocolos em neonatologia e cardiologia em humanos, estudos descritivos sobre a VFC utilizando animais saudáveis e não sedados são escassos na literatura. O objetivo do estudo foi descrever a VFC em cordeiros da raça Bergamácia durante os primeiros 35 dias de idade. Foram realizados exames eletrocardiográficos em 20 cordeiros da raça Bergamácia a partir do nascimento e semanalmente até o 35° dia de idade. A VFC foi analisada pelo intervalo RR normal (batimentos sinusais), pela frequência cardíaca, pelo índice de tônus vasovagal (iTVV), pela raiz quadrada da média do quadrado das diferenças entre intervalos RR normais adjacentes (RMSSD) e pela raiz quadrada da somatória do quadrado das diferenças dos valores individuais em relação ao valor médio, dividido pelo número de iR-R em 90 segundos - VFC global (RMSM). Todos os parâmetros se alteraram ao longo das semanas. A frequência cardíaca média elevou-se entre o nascimento e os primeiros sete dias de idade, com decréscimo nas quatro semanas subsequentes, sendo o menor valor encontrado aos 35 dias de idade (145,63±37,80bpm). Entre 21, 28 e 35 dias de idade, o iTVV elevou-se significativamente, o RMSM a partir do 28º dia, e, aos 35 dias, o RMSSD, reflexo da ativação parassimpática, exibiu diferenças em relação aos momentos subsequentes. O início da predominância parassimpática, refletida nos índices da VFC, particularmente o iTVV, ocorre aos 21 dias de idade. A partir dos 35 dias de idade, os índices RMSM e RMSSD podem ser utilizados como marcadores fidedignos das mudanças nos efeitos simpático e parassimpático sobre o coração de cordeiros.(AU)

Autonomic regulation of heart rate during specific dynamic action associated with digestion in the bullfrog Lithobates catesbeianus

Feeding causes a substantial rise in the aerobic metabolism of all vertebrates, which is met by a rise in heart rate to secure adequate oxygen delivery, as well as intestinal nutrient absorption and transport between organs. To study the autonomic regulation of this postprandial tachycardia in an amphibian, we placed arterial catheters in individuals of the bullfrog, Lithobates catesbeianus (Shaw, 1802), to measure their blood pressure and heart rate. Heart rate in experimental subjects increased from a fasting value of 42.5 ± 2.5 to 52.5 ± 1.6 and 57.5 ± 2.1 min-1 at 24 and 33 hours, respectively, after meals that corresponded to 5% of their body weight. Using an infusion of atropine and propranolol, we demonstrated that part of the postprandial tachycardia can be ascribed to a progressive decrease in parasympathetic tone (26 ± 5% in fasting frogs to 6 ± 5% by 33 hours into digestion), whereas the sympathetic tone remained unaltered at approximately 20%. In addition to the withdrawal of vagal tone, digestion was also associated with an increase in the heart rate upon double-blockade (i.e., the combination of atropine and propranolol) from a fasting value of 44.5 ± 0.9 to 50.8 ± 1.9 min-1 at 33 hours. This indicates that the postprandial tachycardia in frogs, as previously demonstrated for snakes, is partially governed by excitation of non adrenergic, non cholinergic (NANC) factors.

Autonomic regulation of heart rate during specific dynamic action associated with digestion in the bullfrog Lithobates catesbeianus

Feeding causes a substantial rise in the aerobic metabolism of all vertebrates, which is met by a rise in heart rate to secure adequate oxygen delivery, as well as intestinal nutrient absorption and transport between organs. To study the autonomic regulation of this postprandial tachycardia in an amphibian, we placed arterial catheters in individuals of the bullfrog, Lithobates catesbeianus (Shaw, 1802), to measure their blood pressure and heart rate. Heart rate in experimental subjects increased from a fasting value of 42.5 ± 2.5 to 52.5 ± 1.6 and 57.5 ± 2.1 min-1 at 24 and 33 hours, respectively, after meals that corresponded to 5% of their body weight. Using an infusion of atropine and propranolol, we demonstrated that part of the postprandial tachycardia can be ascribed to a progressive decrease in parasympathetic tone (26 ± 5% in fasting frogs to 6 ± 5% by 33 hours into digestion), whereas the sympathetic tone remained unaltered at approximately 20%. In addition to the withdrawal of vagal tone, digestion was also associated with an increase in the heart rate upon double-blockade (i.e., the combination of atropine and propranolol) from a fasting value of 44.5 ± 0.9 to 50.8 ± 1.9 min-1 at 33 hours. This indicates that the postprandial tachycardia in frogs, as previously demonstrated for snakes, is partially governed by excitation of non adrenergic, non cholinergic (NANC) factors.(AU)

Estudo da variabilidade da frequência cardíaca por meio da eletrocardiografia contínua (holter) em cães portadores da síndrome do braquicefálico, antes e após rinoplastia

Filho, Mário dos Santos. Estudo da variabilidade da frequência cardíaca por meio da eletrocardiografia contínua (holter) em cães portadores da síndrome do braquicefálico, antes e após rinoplastia. 2019. Dissertação (Mestrado em Medicina Veterinária, Patologia e Ciências Clínicas). Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ, 2019. As raças braquicefálicas estão cada vez mais presentes nos lares. O cruzamento destas raças na intenção de alcançar caracteres específicos como, focinhos mais curtos, possibilitou características anatômicas maléficas obstrutivas das vias aéreas superiores, que em conjunto formam a síndrome do cão braquicefálico. Algumas das alterações encontradas nestes animais são o palato mole alongado e a estenose das narinas. Estes cães apresentam índice de tônus vasovagal maior que cães não braquicefálicos. O processo obstrutivo de vias aéreas superiores prejudica o trabalho inspiratório reduzindo a inibição parassimpática normal desta fase do ciclo respiratório. Além disso, sabe-se que durante períodos de repouso, a predominância do estímulo vagal pode resultar em grandes pausas entre os batimentos cardíacos, observada principalmente durante o sono, que também pode ser exacerbada nas raças braquicefálicas. Este aumento do tônus parassimpático reflete em aumento da variabilidade da freqüência cardíaca (VFC). A eletrocardiografia contínua possibilita a avaliação da VFC (conjunto de variação na frequência cardíaca ao longo do tempo), indicando a modulação autonômica do coração. Sendo assim, o estudo da VFC nas raças braquicefálicas, antes e após a correção cirúrgica da estenose de narinas poderá trazer à luz do conhecimento o excesso da estimulação parassimpática no que tange a ocorrência de bradiarritmias e suas consequências clinicas, e a possibilidade de melhora do balanceamento autonômico após o tratamento, aumentando a qualidade e expectativa de vida destes pacientes.

Filho, Mário dos Santosi. Study of heart rate variability through continuous electrocardiography (holter) in dogs with brachycephalic syndrome, before and after rhinoplasty. 2019. Dissertation (Master of Veterinary Medicine, Pathology and Clinical Sciences). Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ, 2019. Brachycephalic breeds are increasingly present in homes. The crossing of these breeds in the intention to reach specific characters like shorter muzzles, allowed obstructive anatomical anatomical characteristics of the upper airways, which together form the brachycephalic dog syndrome. Some of the alterations found in these animals are the elongated soft palate and the stenosis of the nostrils. These dogs have a higher vasovagal tonus index than non-brachycephalic dogs. The obstructive upper airway process impairs inspiratory work by reducing the normal parasympathetic inhibition of this phase of the respiratory cycle. In addition, it is known that during periods of rest, the predominance of the vagal stimulus may result in large pauses between the heart beats, observed mainly during sleep, which may also be exacerbated in the brachycephalic races. This increase in the parasympathetic tone reflects an increase in heart rate variability (HRV). Continuous electrocardiography allows the evaluation of HRV (heart rate variation set over time), indicating the autonomic modulation of the heart. Therefore, the study of HRV in the brachycephalic races, before and after the surgical correction of nostril stenosis, may bring to light the knowledge of the excess of parasympathetic stimulation in relation to the occurrence of bradyarrhythmias and their clinical consequences, and the possibility of improving the autonomic balancing after treatment, increasing the quality and life expectancy of these patients.

Evaluation of heart rate as marker of stress during road transport in horses / Evaluation of heart rate as marker of stress during road transport in horses

Background: Nowadays horse transportation represents an increasingly practice as a greater number of horses are subjected to transport for several purpose including sport competitions, breeding and selling. In the past, horses were usually transported by train and ship however, at the present time, they move mainly by road with trailers or vans. Transport represents a potential stressor that might compromise horse performance therefore, the chance to monitor horse welfare during transportation is of great interest. The autonomic nervous system and its regulation of cardiovascular function have been considered suitable indicators of stress and welfare in humans and animals. Measuring the vagal tone provide a best knowledge about stress vulnerability and the magnitude of a stress response. Considering that heart rate (HR) represents the effect of the vagus, the aim of this study was to evaluate if this parameter is an affordable indicator of stress in horses subjected to different experimental conditions concerning the duration and the time of the day of road transportation. Materials, Methods & Results: Twelve clinically healthy athletic Italian Saddle horses, divided into three equal groups, were transported over two different distances (110 Km and 225 Km) at the same time of the day (5.00 pm) (group A and B), and over the same distance (110 Km) during the evening (5.00 pm)

Background: Nowadays horse transportation represents an increasingly practice as a greater number of horses are subjected to transport for several purpose including sport competitions, breeding and selling. In the past, horses were usually transported by train and ship however, at the present time, they move mainly by road with trailers or vans. Transport represents a potential stressor that might compromise horse performance therefore, the chance to monitor horse welfare during transportation is of great interest. The autonomic nervous system and its regulation of cardiovascular function have been considered suitable indicators of stress and welfare in humans and animals. Measuring the vagal tone provide a best knowledge about stress vulnerability and the magnitude of a stress response. Considering that heart rate (HR) represents the effect of the vagus, the aim of this study was to evaluate if this parameter is an affordable indicator of stress in horses subjected to different experimental conditions concerning the duration and the time of the day of road transportation. Materials, Methods & Results: Twelve clinically healthy athletic Italian Saddle horses, divided into three equal groups, were transported over two different distances (110 Km and 225 Km) at the same time of the day (5.00 pm) (group A and B), and over the same distance (110 Km) during the evening (5.00 pm)

Evaluation of heart rate as marker of stress during road transport in horses

Background: Nowadays horse transportation represents an increasingly practice as a greater number of horses are subjected to transport for several purpose including sport competitions, breeding and selling. In the past, horses were usually transported by train and ship however, at the present time, they move mainly by road with trailers or vans. Transport represents a potential stressor that might compromise horse performance therefore, the chance to monitor horse welfare during transportation is of great interest. The autonomic nervous system and its regulation of cardiovascular function have been considered suitable indicators of stress and welfare in humans and animals. Measuring the vagal tone provide a best knowledge about stress vulnerability and the magnitude of a stress response. Considering that heart rate (HR) represents the effect of the vagus, the aim of this study was to evaluate if this parameter is an affordable indicator of stress in horses subjected to different experimental conditions concerning the duration and the time of the day of road transportation. Materials, Methods & Results: Twelve clinically healthy athletic Italian Saddle horses, divided into three equal groups, were transported over two different distances (110 Km and 225 Km) at the same time of the day (5.00 pm) (group A and B), and over the same distance (110 Km) during the evening (5.00 pm) and during the morning (8.00 am) (group A and C). Each journey was divided into 3 parts (T1, T2, T3) on the basis of road characteristics: T1 and T3 periods represented the time spent travelling on secondary roads characterized by several changes of direction and average speed of 35-40 Km/h; T2 was travel duration on nearly completely rectilinear motorways with average speed of 70 Km/h. Mean HR recorded at rest for each horse was 38 ± 3 beats/min. On HR values recorded during transportation one-way ANOVA showed significant statistical differences of HR values in T2 vs T1 and T3 periods within the group A (P < 0.0001) and C (P = 0.003); no significant statistical difference was found in T1, T2 and T3 periods within group B. T tests showed that mean HR values were lower in group B than in group A, and higher in group C than group A only in T2. Discussion: Even if transport includes a series of potential stressors such as handling, loading, unloading, unfamiliar environments, oscillation and vibration of the mean of transport, noise, social regrouping, poor ventilation, deprivation of both food and water; in the present study our recordings showed that HR changed irrespective of the experimental characteristics of the journey including the different duration of each transportation. We found that neither the average speed of the mean of transport or the characteristics of the road determined significant changes in horse HR. We also found no influence of the time of the day on HR trend during transportation in horses. This might be due to the fact that HR varied when posture and other external stimuli changed during transport masking the biological rhythms that usually affect the cardiovascular activity and the HR diurnal variability that suits the needs of different levels of activity at different time of the day. On the basis of these results, HR seemed to be an extremely variable parameter profoundly affected by the temporary responses of the horses to sudden environmental incidents.

ANÁLISE ELETROCARDIOGRÁFICA E DA VARIABILIDADE DA FREQUÊNCIA CARDÍACA MATERNA, FETAL E NEONATAL EM BOVINOS DA RAÇA HOLANDESA VARIEDADE PRETO E BRANCA

O estresse pode interferir no bem-estar animal, assim como gerar alterações cardiovasculares, endócrinas e metabólicas em vacas e fetos durante no período de transição e na fase neonatal, conhecida como período de adaptação, fase de mudanças necessárias para adaptar-se à vida extrauterina. Por conseguinte, o estúdio foi desenhado para descrever o comportamento dos parâmetros eletrocardiográficos (ECG), dos valores normais da frequência cardíaca (FC), dos índices de variabilidade da frequência cardíaca (VFC) e a sua associação com os perfis endócrinos e bioquímicos da vaca prenhe da raça Holandesa variedade preto e branco, assim como do feto e do recém-nascido. Para o ECG, as avaliações foram realizadas no grupo de recém-nascidos separados por sexo, e no grupo das vacas, separadas por período pré-parto e pós-parto. No domínio do tempo, mediu-se, a frequência cardíaca (FC), intervalo entre batimentos (RR), desvio-padrão da média de todos os intervalos RR normais (SDNN), raiz quadrada da média do quadrado das diferenças entre intervalos RR normais adjacentes (RMSSD). No domínio da frequência (por análise FFT) calculou-se a potência normalizada da banda LF (LF normal) e da banda de HF (HF normal), bem como o quociente LF / HF. Foram analisados glicose, magnésio, fósforo, cálcio, sódio e cortisol. Os dados de ECG revelaram que, durante o primeiro mês de vida, não houve diferença nas ondas P, Q, S e T, em intervalos PR, QRS, e ST e na orientação do eixo. Houve uma diferença significativa em amplitude e duração R no intervalo QT. Entre os sexos, a diferença estava na amplitude Q. Foram registrados no estágio fetal, aumento da baixa frequência (LF nu), diminuição da alta frequência (HF nu) bem como no índice SDNN até o nascimento, o que reflete mudança em direção à predominância do sistema nervoso simpático. Em vacas, os índices SDNN e LF/HF registraram queda significativa no período de transição. A diminuição do equilíbrio simpato-vagal (quociente LH/HF) e nos valores do SDNN demonstraram que as vacas chegam ao parto sob um reduzido tônus simpático e parassimpático, que reflete mudança na predominação simpática. As variações e as concentrações dos eletrólitos, glicose e cortisol no plasma sanguíneo têm forte correlação com os índices de VFC. Isso poderia ser atribuído ao desenvolvimento funcional associado com marcada atividade simpato-adrenal dos neonatos durante o período de adaptação, as alterações necessárias para adaptar-se à vida extrauterina. As vacas durante o período de transição são expostas a fatores estressantes que alterám as respostas fisiológicas. Éste trabalho contribui para o conhecimento dos processos de adaptação.

Stress can interfere with animal welfare, as well as generate cardiovascular, endocrine and metabolic disorders in cows and fetuses during the transition period and neonatal phase, known as adjustment period, phase changes necessary to adapt to extrauterine life. Therefore, the study was design to describe the electrocardiographic parameters (ECG), the normal range of heart rate (HR), the indices of heart rate variability (HRV) and the association with endocrine and biochemical profiles of Holstein pregnant cow, her fetus and neonate. The study was designed to evaluate the physiological changes during the adaptation period and in cows during the transition period between three weeks before and after delivery. The evaluations were done into the group of neonates between female and male and in pre and post-delivery cows for ECG. In time domain, heart rate (HR), beat-to-beat interval (RR), the square root of variance of RR intervals (SDNN), and square root of the mean squared differences of successive RR intervals (RMSSD) were assessed. The studied parameters of frequency domain were, low frequency measured in normalized units (LF nu), high frequency measured in normalized units (HF nu), and LF/HF ratio. Glucose, magnesium, potassium, phosphorus, calcium, sodium and cortisol concentrations in plasma were determined. The ECG data revealed that during the first month of life, no differences were observed in P, Q, S and T waves, in PR, QRS, and ST intervals and in axis orientation. There was a significant difference in R amplitude and duration in the QT interval. Among sexes, the difference was in the Q amplitude. In the fetal stage, an increase in low frequency (LF nu) and a decrease in high frequency (HF nu) and the SDNN index to birth was recorded, this reflects a shift toward dominance of the sympathetic nervous system. Cows in the transition period, the SDNN and the ratio LF / HF displayed a significant drop. The decrease in the sympathetic-vagal balance (ratio LH / HF) and SDNN values showed that the cows reached to birth under a reduced sympathetic and parasympathetic tone, reflecting a change toward sympathetic domain. The variations and concentrations of electrolytes, glucose and cortisol in blood plasma had a strong correlation with the HRV indexes. This could be attributed to the functional development associated with a marked sympathetic- adrenal activity of neonates during the adaptation period, changes that are necessary to adapt to extra uterine life. In cows during the transition period, where physiological adjustments are the respond to the exposition to stressors. This work contributes to the knowledge of the processes of adaptation.

Influência do posicionamento sobre a variabilidade da freqüência cardíaca não-espectral em cães saudáveis / Influence of positioning on nonspectral rate variability in healthy dogs

As alterações da freqüência cardíaca mediante as contribuições dos tônus simpáticso e parassimpáticos constituem a variabilidade da freqüência cardíaca. Embora se acredite que variações posturais possam influenciar no balanço simpato-vagal e, portanto, na determinação de tal parâmetro, desconhece-se seu comportamento em cães avaliados em posições distintas do decúbito lateral direito. Assim, este estudo foi concebido com o escopo de avaliar a influência do posicionamento corporal na determinação da variabilidade da freqüência cardíaca não-espectral em cães saudáveis. Uma vez analisados, os resultados mostraram-se semelhantes, permitindo concluir que, nas condições experimentais propostas, a regulação cardiovascular autônoma não foi influenciada pelo posicionamento corporal(AU)

Alterations in heart rate are attributable to the contributions of sumpathetic and parasympathetic tone represent heart rate variability. Althought it is believed that postural variations might play a role in sympsthovagal balance and therefore influence the determination of nonspectral heart rate variability in healthy dogs. Analysis of data documented similar results, which permited concluding that, under the proposed experimental conditions, autonomic cardiovascular regulation was not influenced by body position(AU)

Influência do posicionamento sobre a variabilidade da freqüência cardíaca não-espectral em cães saudáveis / Influence of positioning on nonspectral rate variability in healthy dogs

As alterações da freqüência cardíaca mediante as contribuições dos tônus simpáticso e parassimpáticos constituem a variabilidade da freqüência cardíaca. Embora se acredite que variações posturais possam influenciar no balanço simpato-vagal e, portanto, na determinação de tal parâmetro, desconhece-se seu comportamento em cães avaliados em posições distintas do decúbito lateral direito. Assim, este estudo foi concebido com o escopo de avaliar a influência do posicionamento corporal na determinação da variabilidade da freqüência cardíaca não-espectral em cães saudáveis. Uma vez analisados, os resultados mostraram-se semelhantes, permitindo concluir que, nas condições experimentais propostas, a regulação cardiovascular autônoma não foi influenciada pelo posicionamento corporal

Alterations in heart rate are attributable to the contributions of sumpathetic and parasympathetic tone represent heart rate variability. Althought it is believed that postural variations might play a role in sympsthovagal balance and therefore influence the determination of nonspectral heart rate variability in healthy dogs. Analysis of data documented similar results, which permited concluding that, under the proposed experimental conditions, autonomic cardiovascular regulation was not influenced by body position

Evaluation of heart rate as marker of stress during road transport in horses / Evaluation of heart rate as marker of stress during road transport in horses

Background: Nowadays horse transportation represents an increasingly practice as a greater number of horses are subjected to transport for several purpose including sport competitions, breeding and selling. In the past, horses were usually transported by train and ship however, at the present time, they move mainly by road with trailers or vans. Transport represents a potential stressor that might compromise horse performance therefore, the chance to monitor horse welfare during transportation is of great interest. The autonomic nervous system and its regulation of cardiovascular function have been considered suitable indicators of stress and welfare in humans and animals. Measuring the vagal tone provide a best knowledge about stress vulnerability and the magnitude of a stress response. Considering that heart rate (HR) represents the effect of the vagus, the aim of this study was to evaluate if this parameter is an affordable indicator of stress in horses subjected to different experimental conditions concerning the duration and the time of the day of road transportation. Materials, Methods & Results: Twelve clinically healthy athletic Italian Saddle horses, divided into three equal groups, were transported over two different distances (110 Km and 225 Km) at the same time of the day (5.00 pm) (group A and B), and over the same distance (110 Km) during the evening (5.00 pm)

Background: Nowadays horse transportation represents an increasingly practice as a greater number of horses are subjected to transport for several purpose including sport competitions, breeding and selling. In the past, horses were usually transported by train and ship however, at the present time, they move mainly by road with trailers or vans. Transport represents a potential stressor that might compromise horse performance therefore, the chance to monitor horse welfare during transportation is of great interest. The autonomic nervous system and its regulation of cardiovascular function have been considered suitable indicators of stress and welfare in humans and animals. Measuring the vagal tone provide a best knowledge about stress vulnerability and the magnitude of a stress response. Considering that heart rate (HR) represents the effect of the vagus, the aim of this study was to evaluate if this parameter is an affordable indicator of stress in horses subjected to different experimental conditions concerning the duration and the time of the day of road transportation. Materials, Methods & Results: Twelve clinically healthy athletic Italian Saddle horses, divided into three equal groups, were transported over two different distances (110 Km and 225 Km) at the same time of the day (5.00 pm) (group A and B), and over the same distance (110 Km) during the evening (5.00 pm)

Efeito do pré-tratamento com amitraz sobre a febre induzida por lipopolissacarídeo (LPS) de E. coli ou interleucina-1"beta" (IL-1"beta"), em coelhos

A endotoxemia é uma afecção importante nas diversas espécies animais decorrente da ação de lipopolissacarídeos liberados na circulação durante o choque séptico, os quais ativam a cascata inflamatória induzindo a síntese e liberação de citocinas (TNF, IL-1, IL-6), capazes de produzir febre. É bastante comum, em eqüinos, quadros de cólica gastrintestinal devido à intoxicação por amitraz (AMZ), um acaricida formamidínico. A compactação de cólon é uma das conseqüências dessa intoxicação principalmente, pela ação desta substância sobre receptores adrenérgicos a-2. Sabendo-se que as substâncias agonistas de receptores a-2 produzem um aumento do tônus vagal e que a estimulação das fibras vagais, aferentes e eferentes reduz a liberação de TNF-a, o objetivo deste estudo foi avaliar os efeitos do AMZ sobre a febre, quando administrado antes da indução experimental de endotoxemia com LPS ou da administração de IL-1ß. Foram utilizados, em duas fases experimentais, 40 coelhos machos, raça Branco da Nova Zelândia, com peso entre 2,5 e 3,5 kg. Na primeira fase, para determinação da dose hipnótica 50% do AMZ (DHA50%), os animais foram separados em 4 grupos iguais de cinco animais (G1, G2, G3, G4). Na segunda fase experimental os animais foram divididos em 8 grupos iguais (GI, GII, GIII, GIV, GV, GVI, GVII, GVIII), compostos de cinco animais cada, os quais foram pré-tratados com salina (NaCl 0,9%), AMZ (0,3 mg.kg-1) ou DMSO e desafiados com salina, LPS(1,5 æg.kg-1) ou IL-1ß (100 ng.kg-1). A DHA50% e DSHA, para coelhos, foi 0,55 mg.kg-1 e 0,3 mg.kg-1, respectivamente. A febre observada no grupo AMZ-LPS foi inferior àquela demonstrada pelo grupo sal-LPS e superior àquela anotada no grupo DMSO-LPS. Concluiu-se que o AMZ, na dose de 0,3 mg.kg-1, diminui a intensidade da resposta febril ao LPS, mas o DMSO demonstra maior efetividade sobre a febre induzida por LPS. O AMZ não bloqueia a febre causada pela IL-1ß

Endotoxemia is an important condition in several species being induced by lipopolysaccharides. Released into the bloodstream during the septic shock, they activate the inflammatory cascade leading to syntheses and release of cytokines (TNF, IL-1, IL-6) which are able to produce fever. Colic in horses is frequently observed after treatment with amitraz, a formamidine pesticide. Large colon impactation is one of the consequences of intoxication, mainly by acting on a-2-adrenergic receptors. As a-2 agonists has been proven to produce an increase of the vagus tone, ant that the stimulation of afferent and efferent vagus has been shown to reduced TNF release, the main goal of this study was to evaluate the effects of amitraz over fever when administered before induction of experimental endotoxemia with LPS or IL-1ß administration. Forty male rabbits of the New Zealand white breed weighing 2.5-3.5 kg were used. The present study consisted of two experimental phases. In the first phase, to determine the 50% hypnotic dose of amitraz (DHA50%), the rabbits were divided into four groups (n=5). In the second phase, the rabbits were divided into eight groups (n=5). They were submited to treatment with saline (NaCl 0,9%), AMZ (0.3 mg.kg-1) or DMSO 10 minutes before intravenous injection of saline, LPS (1.5 mg.kg-1) or IL-1ß (100 ng.mg.kg-1). The DHA50% and DSHA for rabbits was 0.55 mg.kg-1 and 0.3 mg.kg-1, respectively. The results demonstrated that the fever observed in AMZ-LPS group was comparatively lower than the fever induced in the group sal-LPS and higher than the fever induced in the group DMSO-LPS. Therefore, It was concluded that amitraz, at the dose of 0,3 mg/kg, decreases the intensity of febrile response to LPS, despite the fact that DMSO is more effective over fever induced by LPS. On the other hand, amitraz does not interfere with the febrile response induced by intravenous administration of IL-1ß