Heart rate variability and vasovagal tone index in brachycephalic dogs.

Brachycephalic breeds of dogs, most of which show signs of the brachycephalic syndrome may have greater parasympathetic stimulation than other breeds, leading to higher values of heart rate variability and vagal tone index. The aim of this study was to establish a computerized electrocardiographic study and an assessment of the vagus sympathetic balance through heart rate variability and vagal tone index of five brachycephalic breeds compared to mesocephalic dogs. Sixty dogs were used, divided into groups made up of Boxers, English Bulldogs, French Bulldogs, Pugs, Shih-Tzu and no defined breed mesocephalic dogs. Statistical analysis was carried out using the Shapiro-Wilk test, Kruskal-Wallis and Dunn's test or ANOVA and Bonferroni (p<0.05). In the evaluation of vagal sympathetic balance among all the dogs, there was a negative correlation between heart rate and HRV 10RR (r = - 0.7678; p < 0.0001), HRV 20RR (r = - 0.8548, p < 0.0001) and VVTI (r = - 0.2770; p = 0.0321). It can therefore be concluded that the dog's breed and morphology did not alter its electrocardiographic parameters or heart rate variability. The vagal tone index, which in other studies differed in brachycephalic dogs, showed no difference when compared separately in brachycephalic breeds.

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

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

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

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

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

Adipose tissue derived mesenchymal stem cell transplantation in the treatment of ischemia/reperfusion induced acute kidney injury in rats. Application route and therapeutic window1.

PURPOSE: To evaluate renal repair in rats who had renal infarction induced by the obstruction of blood flow in the renal artery and were treated with transplantation of adipose tissue derived mesenchymal stem cell. METHODS: 16-week-old Wistar rats (n=72) were used, submitted to celiotomy and had of the renal artery and vein clipped for 24 hours. The animals were randomly assigned to 10 experimental homogeneous groups, corresponding to the treatments with phosphate-buffered saline (PBS) or adipose tissue derived mesenchymal stem cell (ADSC), duration of application (24 or 48 hours), and site of transplantation (lateral vein of the tail or intrarenal). After the treatments were performed, at 8 and 31 days, four animals in each group were subjected to left nephrectomy for histological studies. RESULTS: Histologically, a higher amount of cell debris and tubules devoid of the epithelium and a higher degree of necrosis were observed in the groups treated with PBS, as opposed to a low degree of necrosis and higher tubular vascularization in the groups treated with ADSC, particularly in the group treated with intrarenal ADSC 48 hours after injury. CONCLUSION: The transplantation of ADSC positively contributed to the replacement of necrotic tissue by renal tubular cells, vascularization of the renal parenchyma, and restoration of the organ function.

Adipose tissue derived mesenchymal stem cell transplantation in the treatment of ischemia/reperfusion induced acute kidney injury in rats. Application route and therapeutic window

Abstract Purpose: To evaluate renal repair in rats who had renal infarction induced by the obstruction of blood flow in the renal artery and were treated with transplantation of adipose tissue derived mesenchymal stem cell Methods: 16-week-old Wistar rats (n=72) were used, submitted to celiotomy and had of the renal artery and vein clipped for 24 hours. The animals were randomly assigned to 10 experimental homogeneous groups, corresponding to the treatments with phosphate-buffered saline (PBS) or adipose tissue derived mesenchymal stem cell (ADSC), duration of application (24 or 48 hours), and site of transplantation (lateral vein of the tail or intrarenal). After the treatments were performed, at 8 and 31 days, four animals in each group were subjected to left nephrectomy for histological studies. Results: Histologically, a higher amount of cell debris and tubules devoid of the epithelium and a higher degree of necrosis were observed in the groups treated with PBS, as opposed to a low degree of necrosis and higher tubular vascularization in the groups treated with ADSC, particularly in the group treated with intrarenal ADSC 48 hours after injury. Conclusion: The transplantation of ADSC positively contributed to the replacement of necrotic tissue by renal tubular cells, vascularization of the renal parenchyma, and restoration of the organ function.

Weight loss improves arterial blood gases and respiratory parameters in obese dogs.

Canine obesity is a common medical disorder and a known risk factor for associated diseases; it can seriously influence various physiological functions, thereby limiting the longevity of the animal. In this study, we evaluated potential respiratory alterations in obese dogs before and after being subjected to caloric restriction to decrease their body weight by 20%, and compared those dogs with control dogs with ideal body condition score. The animals were divided into three experimental groups: GI (obese dogs; n = 11); GII (obese dogs after weight loss, same animals as in GI); GIII (control dogs; n = 11). We evaluated lung function by spirometry and arterial blood gases. Statistical analysis included paired or non-paired Student's t test. Compared with dogs within an ideal body condition score (GIII), obese dogs (GI) had a low arterial partial pressure of oxygen (p < 0.05); decreased tidal volume (p < 0.005), inspiratory time and expiratory time (p < 0.05); and an increased respiratory rate (p < 0.005). After losing weight (GII), no differences with control dogs (GIII) were verified. The results suggested that obese dogs have an improvement in respiratory function with weight loss, but further investigations in a larger group of dogs are advised to confirm these findings.

Evaluation of environment and a feline facial pheromone analogue on physiologic and behavioral measures in cats.

Objectives This study assessed behavioral and physiologic stress parameters in cats placed in two environments: home and the veterinary hospital. With a widely used scale, several parameters were assessed, including respiratory rate (RR), heart rate (HR), systolic blood pressure (SBP), vagosympathetic responses using calculated intervals (heart rate variability [HRV]10, HRV20 and vasovagal tonus index [VVTI]) and 'stress attitude', such as struggling, vocalization and agitation during handling. In addition, we evaluated whether a feline facial pheromone analogue (FFPA) had an effect on any of these measures in either environment. Methods Using a placebo and a pheromone substance, we evaluated 30 adult and healthy cats at home and in veterinary hospitals. Statistical analyses were performed using the Shapiro-Wilk, Kruskal-Wallis, and Dunn or ANOVA and Tukey tests, as well as Spearman's correlation ( P <0.05). Results We found that exposure to FFPA did not reduce the effects of stress. Some parameters presented differences with regard to environment: the RR was 45 and 70 breaths/min and stress attitude score was 1.3 and 0.0 for cats evaluated at home and at the hospital, respectively. The HR and two vagosympathetic responses were also different between the two environments, with a HR of 160 and 187 beats/min, HRV10 of 14.24 and 14.00, and HRV20 of 14.89 and 14.65 in cats at home and the hospital, respectively. There was no variation in SBP and VVTI parameters between the environments. Conclusions and relevance Exposure to FFPA does not reduce the physiologic and behavioral changes measured in this study. Furthermore, environmental change, physical restraint and manipulation during the physical examination alter RR, HR, HRV and behavior but not SBP and VVTI. This study is relevant because physiologic and behavioral stress can affect the quality and interpretation of physical examination results. This study presents detailed data that show the effects of environment and manipulation on such parameters. Furthermore, this study shows a lack of effect of FFPA on any of these parameters.

Electrocardiographic patterns of Mangalarga Marchador horses before and after implementation of the marcha gait / Padrões eletrocardiográficos em equinos da raça Mangalarga Marchador antes e após a execução da marcha

ABSTRACT: The aim of this study was to evaluate the electrocardiographic parameters in Mangalarga Marchador horses submitted to marcha exercise. Twenty-four Mangalarga Marchador horses, thirteen females and eleven males, 6.4±2.7 years old with a mean weight of 428.3±24.7kg, were used. Electrocardiograms were recorded in two different moments: rest and immediately after exercise (40 minutes of aerobic exercise, marcha gait). The electrocardiographic variables analyzed were cardiac rhythm, heart rate (HR), duration of P wave, QRS complex, PR and QT intervals, amplitudes of P, R and T waves, and analysis of QT corrected (QTc) according to Bazett's formula (QT/√RR). Variables were analyzed for normality with Kolmogorov-Smirnov test and paired t-test, considering P<0.05. Rhythm analysis revealed 91.7% of sinus rhythm and 8.3% of sinus arrhythmia in rest, with mean HR of 45.7±12.7 beats minute-1, and 100% of sinus tachycardia, with mean HR of 77.3±13.5 beats minute-1 after exercise (P<0.0001). In post-exercise, it was possible to observe decreases in P wave duration (P=0.0121), PR interval (P=0.0007) and QT interval (P<0.0001) and increase of QTc (P=0.0039) and R wave amplitude (P=0.0033). There were no significant differences for amplitude of P and T waves and QRS complex related to atrioventricular enlargement. Although QT interval decreased after exercise, there was an increase on QTc after exercise, indicating changes in ventricular repolarization. It was possible to conclude that the imposed exercise (marcha gait) led to electrocardiographic alterations without causing pathological arrhythmias.

RESUMO: O objetivo deste estudo foi avaliar os parâmetros eletrocardiográficos de equinos da raça Mangalarga Marchador antes e após a execução da marcha. Para tal, foram usados 24 equinos, treze fêmeas e onze machos, com idade média de 6,4±2,7 anos e peso médio de 428,3±24,7kg. Eletrocardiogramas foram registrados em dois momentos: antes e imediatamente após atividade física (40 minutos de marcha). As variáveis eletrocardiográficas analisadas foram ritmo cardíaco, frequência cardíaca (FC), duração da onda P, complexo QRS, intervalos PR e QT, amplitudes das ondas P, R e T e análise do QT corrigida (QTc) de acordo com a fórmula de Bazett (QT/√RR). As variáveis foram analisadas quanto à normalidade (teste de Kolmogorov-Smirnov), seguido da comparação usando teste-t pareado (P<0,05). A análise revelou 91,7% de ritmo sinusal e 8,3% de arritmia sinusal no repouso, com FC média de 45,7±12,7bpm e 100% de taquicardia sinusal após o exercício, com FC média de 77,3±13,5bpm (P<0,0001). No pós-exercício, foi possível observar reduções significativas na duração da onda P (P=0,0121), no intervalo PR (P=0,0007) e no intervalo QT (P<0,0001), além de aumentos significativos de QTc (P=0,0039) e amplitude da onda R (P=0,0033). Não foram registradas diferenças para a amplitude das ondas P e T e na duração do complexo QRS. Apesar da redução no intervalo QT após o exercício, houve um aumento no QTc, indicando alterações na repolarização ventricular. Foi possível concluir que a atividade física (marcha) gerou alterações eletrocardiográficas, sem causar arritmias patológicas.

Avaliação da pressão arterial sistêmica em cães obesos: comparação entre os métodos oscilométrico e doppler ultrassônico / Systemic blood pressure evaluation by oscillometric versus doppler ultrasonographic methods in obese dogs

A obesidade é o problema nutricional que mais acomete os cães e pode causar vários efeitos deletérios a saúde animal. No entanto, o efeito desta condição sobre a pressão arterial sistólica (PAS) em cães obesos é controverso. Os métodos indiretos de mensuração da PAS são os mais comumente utilizados na medicina veterinária para o diagnóstico da hipertensão sistêmica, por serem mais práticos e de fácil acesso. Não foram localizados na literatura estudos que tenham comparado os dois métodos para esta avaliação em cães obesos. Diante do exposto, o objetivo desse estudo foi avaliar a PAS em cães obesos, comparando os métodos indiretos de mensuração da pressão arterial, oscilométrico e doppler ultrassônico, a fim de verificar as diferenças nos valores obtidos, como também o método mais indicado para aferir a PAS em cães nesta condição. Foram avaliados 50 cães, incluindo 25 obesos com escore de condição corporal (ECC) médio de 8,42±0,50 e 25 cães com peso corporal ideal com ECC médio de 4,56±0,51. Os resultados revelaram valores superiores da PAS obtidos pelo método doppler (152±16mmHg) comparados ao oscilométrico (136±11mmHg). A análise de correspondência determinada por análise estatística multivariada demonstrou maior correspondência entre a condição corporal e o método de avaliação da PAS. Esses achados sugerem que o método indireto doppler pode aferir com mais precisão os valores de PAS em cães obesos.(AU)

Obesity is the most common nutritional problem in dogs and it can cause various harmful effects on animal health. However, the effect of this condition on systolic blood pressure (SBP) in obese dogs is controversial. The indirect method of measuring PAS is the most commonly used in veterinary medicine for the diagnosis of systemic hypertension, because it is more practical and easy to access. There is little scientific information about the comparison of the two non-invasive methods of measurement of blood pressure in obese dogs. Therefore, the objective of this study was to evaluate the SBP in obese dogs by comparing both indirect methods of measuring blood pressure, with oscillometric and doppler vascular in order to verify the differences in blood pressure values, but also the best method to assess the SBP dogs in this body score condition. The study complain blood pressure measurement of 50 dogs, with were divided in obese dogs with mean body condition score (BCS) of 8.42±0.50 (n=25) and dogs with ideal BCS of 4.56±0.51 (n=25). At comparison of blood pressure values, SBP values obtained by doppler method (152±16mmHg) were higher than the oscillometric (136±11mmHg). Correspondence analysis determined by multivariate statistical analysis showed correlation between body condition and the procedure of the SBP. These findings suggest that the indirect method doppler can better reflect the SBP in obese dogs.(AU)

Doxorubicin induced dilated cardiomyopathy in a rabbit model: an update.

Dilated cardiomyopathy (DCM) is characterized by chamber dilation and cardiac dysfunction. Because of the poor prognosis, models are needed for the investigation of and development of new therapeutic approaches, as well as stem cell therapy. Doxorubicin (DOX), used as chemotherapeutic agent, is reported to be cumulative cardiotoxic causing DCM. The aim of the study was to investigate the onset of systolic dysfunction using echocardiography in rabbits receiving two different doses of DOX (1mg/kg twice a week and 2 mg/kg once a week). Twenty rabbits were treated with doxorubicin in two different doses for 6 weeks and compared with a control group treated with NaCl 0.9%. The effect of doxorubicin on the myocardium was investigated with histological analysis and scanning electron microscopy of left ventricle (LV), as well as in the interventricular septum (IVS) and right ventricle (RV). The results showed a high mortality rate for rabbits receiving 2 mg/kg once a week. A significant reduction in systolic function was present in animals treated with DOX after 6 weeks, with decreased ejection fraction and shortening fraction. Histology and electron microscopy revealed vacuolization, intracytoplasmic granulation, necrosis and interstitial fibrosis in LV, as well as in the IVS and RV. Doxorubicin induced changes are present in the LV, RV and IVS, and the administration at the dose of 1 mg/kg twice a week for only 6 weeks is safe and sufficient to induce DCM in rabbits.

Effects of acute normovolemic anemia on hemodynamic parameters and Acid-base balance in dogs.

The aim of this study was to evaluate the hemodynamic and acid-base status of dogs subjected to acute normovolemic anemia. The dogs (n = 10) were evaluated 15 minutes and 24 hours after induction of anemia (hematocrit below 18%) with blood withdrawal and simultaneously replacement of same volume of Ringer's lactate solution and hydroxyethyl starch-based solution in a 2 : 1 ratio. The cardiac output was measured by Doppler echocardiography and blood pressure by oscillometric device, and posteriorly hemodynamic parameters were calculated. The anemic groups had increase in cardiac index (P < .05) (3.82 ± 1.05 to 5.86 ± 1.49 and 5.81 ± 1.63 L/min × m(2)) and decreases (P < .05) in the indices of total peripheral resistance (6797.81 ± 3060.22 to 3220.14 ± 1275.02 and 3887.74 ± 1394.89 dina·seg/cm(5) × m(2)) and oxygen delivery (7942.84 ± 3344.00 to 4021.68 ± 1627.00 and 4430.82 ± 1402.61 mL/min × m(2)), respectively. There were no significant changes in pH, but PaO(2) and SaO(2) values were increased, and PaCO(2) reduced in anemic dogs (P < .05). Therefore, acute normovolemic anemia can create significant hemodynamic changes and despite some hemogasometric changes, there were no changes in the acid-base status in dogs.

Cardiac function in dogs with chronic Chagas cardiomyopathy undergoing autologous stem cell transplantation into the coronary arteries.

This study assessed the effects of a single intracoronary injection of autologous stem cells on the cardiac function of dogs with Chagas cardiomyopathy. Bone-marrow-derived stem cells were delivered into the right and left coronary arteries of 5 mature dogs with mildly compromised cardiac function due to chronic Chagas cardiomyopathy. Blood pressure and electrocardiographic and echocardiographic parameters were recorded at monthly intervals for 6 mo in the 3 dogs that survived. Although no changes were observed in the electrocardiogram and blood pressure, there was a significant increase in peak velocity of aortic flow 3 mo after stem cell transplantation. Pre-ejection period, isovolumic relaxation time, and the Tei index of myocardial performance were reduced significantly 4 mo after the procedure. All significant changes persisted to the end of the study. The results suggest that the transplantation of autologous bone-marrow-derived stem cells into the coronary arteries of dogs with Chagas cardiomyopathy may have a beneficial effect but the small number of dogs studied was a limitation.

Utilização de probiótico e de lactulose no controle de hiperamonemia causada por desvio vascular portossistêmico congênito em um cão / Use of probiotic and lactulose to control hyperammonemia secundary to a congenital portosystemic shunt in a dog

O desvio vascular portossistêmico pode ser congênito ou adquirido nos cães. A enfermidade pode levar a alterações neurológicas decorrentes de encefalopatia hepática e a hiperamonenia é um dos mecanismos implicados na fisiopatologia deste quadro. O tratamento clínico visa a reduzir os níveis séricos de amônia com o uso de antibióticos e lactulose. Em humanos com hepatopatias, os probióticos podem ser utilizados para reduzir a hiperamonemia. A resposta clínica e laboratorial de um cão com desvio vascular portossistêmico foi demonstrada com a utilização de lactulose e de probiótico, isoladamente e associados, sendo que a melhor evolução foi obtida na terapia conjunta.

The portosystemic shunt may be congenital or acquired in dogs. The disease can cause neurologic signs manifested by hepatic encephalopathy. The hyperammonemia is a mechanism involved on the physiopathology of this disorder. The objective of the clinical treatment is to decrease the levels of ammonia with antibiotics and lactulose. In human medicine, probiotics are used to reduce the hyperammonemia in patients with hepatic diseases. This report compares the use of lactulose and probiotic monotherapy and in association in a dog with congenital portosystemic shunt, showing the patientÆs clinical and laboratorial evolutions. The better clinical and laboratorial reponse was obtained with the association of lactulose and probiotic.