Rodrigo Bernardes Nogueira

Heart rate variability parameters of myxomatous mitral valve disease in dogs with and without heart failure obtained using 24-hour Holter electrocardiography

Time-domain heart rate variability (HRV) parameters and the correlation between echocardiography and Holter examinations in dogs with myxomatous mitral valve disease (MMVD) were determined. Holter examination was also performed at different time frames: an entire 24-hour period, a four-hour period during sleep, and a four-hour period while awake. Ten healthy (control group) and 28 MMVD dogs, 15 with and 13 without heart failure, were evaluated. The SDANN (sd of the mean normal RR intervals for all five-minute segments during 24-hour Holter) and pNN50 (percentage of differences between adjacent normal RR intervals that are >50 ms computed over 24-hour Holter) variables were significantly lower in the dogs with MMVD heart failure. The differences in HRV between the groups were only detected during the 24-hour evaluation period (P < 0.05). There were high correlations (canonical analysis) between Holter and echocardiography examinations when considering pNN50, SDANN, and LA/AO (left atrial to aortic root ratio) (r = 0.92; P < 0.05), indicating that both are important in evaluating MMVD dogs. SDANN and pNN50 are measures of parasympathetic control of the heart, and thus, it is possible to infer that the MMVD dogs exhibit parasympathetic withdrawal during the development of heart failure.

Excreção de oocistos de Cryptosporidium parvum em cães saudáveis das cidades de Lavras e Viçosa, Estado de Minas Gerais, Brasil

The frequency of Cryptosporidium parvum oocyst excretion in healthy dogs was determined. Fecal samples of 269 animals were collected, from urban and rural areas, in two cities, Lavras and Vicosa, from Minas Gerais state, Brazil. The detection of C. parvum oocysts was carried out by a ELISA direct kit (Alexon - Trend, USA). From all samples analyzed, five (1.85%) were positive. Differences between oocyst excretion frequency in dogs from rural and urban areas were not observed.

Alterations in the large peripheral circulation in dogs with heart failure.

The femoral artery is responsible for perfusion of a large muscular region that can be involved in the exercise intolerance shown by dogs with spontaneous heart failure. The objective of the present study was to evaluate blood flow in the femoral artery by transcutaneous duplex Doppler ultrasonography (TDU) in 50 healthy dogs and 50 dogs with spontaneous heart failure. The group of dogs with heart disease was divided according to the functional class of the heart failure. The TDU measurements were: peak systolic velocity (PSV), early retrograde (EDV) and end diastolic velocities (EnDV), mean velocity (MV), pulsatility index (PI), resistivity index (RI) and femoral flow volume (FFV). In healthy dogs, PSV and FFV were significantly higher than in dogs with heart disease. FFV was reduced mainly in patients with moderate and severe heart failure. TDU allowed for non-invasive detection and quantification of pathological alterations in peripheral hemodynamics.

Longitudinal strain and strain rate by two-dimensional speckle tracking in non-sedated healthy cats.

Two dimensional speckle tracking (2D-ST) is a relatively new tool that has been used in veterinary medicine to quantify myocardial function. However, there is little information about the use of this tool in healthy cats. Thus, the aim of this study was to evaluate left ventricular longitudinal strain and strain rate in non-sedated healthy cats, as well as longitudinal velocity and displacement, by means of 2D-ST echocardiography. Thirty non-sedated healthy cats were examined and 2D images were obtained for 2D-ST analyzes. The global mean strain and strain rate was -15.65 ± 5.46% and -1.80 ± 0.59 s(-1), respectively. Velocity and displacement were 1.41 ± 0.87 cm/s and 1.27 ± 0.80 mm, respectively. Thus, 2D-ST demonstrated to be feasible for measuring left ventricular longitudinal strain, strain rate, velocity and displacement in cats and preliminary reference values for non-sedated healthy cats can be established from the results of this study.

Evaluation of aging on muscle blood flow in conscious healthy dogs by duplex Doppler ultrasonography

According to a study conducted on a population of 9,248 subjects, cardiac diseases are the second most prevalent cause of death in the dog. During the last decades, a common scenario has been the increase on life expectancy of dogs. The exact relationship between the negative modifications of cardiovascular function and the development of specific cardiovascular diseases is difficult to ascertain, and also, the effect of age per se on vascular impedance is important. It may result in limited cardiovascular reserve under conditions of increase demand in senescent animals. To evaluate the effect of age on the peripheral vasculature specifically, the objective of this study was to compare parameters of the regional blood flow as well as compliance and resistance indexes in the femoral arterial system of younger and older conscious healthy dogs by duplex Doppler ultrasonography. The data were collected from 16 mixed-breed dogs divided into two groups: young and old healthy dogs. In all dogs Doppler spectra blood flow patterns of the femoral artery were triphasic. Significant differences were not found between the parameters measured for young and old groups. Despite this, the average value of femoral flow volume in the older group was approximately 50% lower than the younger group. This finding could play an important role in limiting exercise response with age. In order to validate these speculations, further studies should be performed in aged dogs.

Spectral analysis of femoral artery blood flow waveforms of conscious domestic cats.

The qualitative and quantitative aspects of femoral artery blood flow waveform spectra were evaluated in 15 male and 15 female Persian and mixed breed domestic cats (Felis catus), which were healthy and not sedated, using duplex Doppler ultrasonography (DDU). Spectral Doppler demonstrated a biphasic characteristic in 16 (53.34%) of the animals evaluated, and a triphasic characteristic in the 14 (46.66%) remaining animals. The systolic blood pressure and heart rate values were within the normal range for the species. The quantitative parameters evaluated, based on the spectral Doppler, were as follows: systolic velocity peak (SVP), recent diastolic velocity peak (RDVP), end diastolic velocity peak (EDVP), mean velocity (MV), integral velocity time (ITV), artery diameter (AD), femoral flow volume (FFV), pulsatility index (PI), resistive index (RI), systolic peak acceleration time (AT) and deceleration time (DT). The respective mean values were: 36.41 ± 7.33 cm/s, 4.69 ± 0.90 cm/s, 10.74 ± 2.74 cm/s, 23.06 ± 4.86 cm/s, 3.91 ± 1.05 cm, 0.17 ± 0.04 cm, 0.11 ± 0.08 cm3, 3.85 ± 0.19, 1.40 ± 0.20, 39.84 ± 7.38 ms, and 114.0 ± 22.15 ms. No significant differences were found between males and females. The analyses carried out on the femoral artery flow spectrum obtained by DDU showed that it is easy to use and highly tolerated in non-sedated, healthy cats. It appears that DDU may be a useful diagnostic technique, but further studies are needed to evaluate how it compares with invasive telemetric methodology or high-definition oscillometric waveform analytic techniques.

Muscular arterial impedance in dogs with chronic degenerative mitral valve disease.

Systemic vascular impedance represents the retrograde strength of the blood flow to the left ventricle, thus it is one of the main compounds of afterload. Mitral regurgitation is markedly sensitive to afterload alterations. The purpose of this study was to evaluate muscular arterial impedance in dogs with chronic degenerative mitral valve disease (CDMVD) by use of duplex Doppler ultrasonography (DDU), since its technique there was not used before to determine impedance index in dogs with CDMVD. For this purpose, ten healthy dogs and ten dogs with CDMVD were used. Some parameters related to blood flow impedance in the common femoral artery were measured by DDU: pulsatility index (PI), resistance index (RI), high-resistance index (HRI), and acceleration velocity (AC) and deceleration velocity (DC) of the systolic peak. The results showed that RI and HRI were significantly higher in animals with CDMVD than in healthy animals. These findings showed that DDU provides quantitative data related to vascular impedance. Broader studies may therefore provide new aspects related to physiopathology and therapy in CDMVD patients.

Diagnóstico ecodopplercardiográfico da fibrose crônica da válvula mitral em cão

A ten year-old male Poodle dog, weighing 3kg, was referred to the Veterinary Hospital of UFMG due to nocturnal coughing, exercise intolerance, weakness and weight loss. Physical examination revealed pale mucous membranes, prolonged capillary refill time, holosystolic regurgitant murmur at left apex and signs of congestive heart failure. M-mode, two-dimensional, and Doppler echocardiography revealed mitral chronic valvular disease

Avaliação por eletrocardiografia contínua (holter) em cães da raça Pastor Alemão praticantes de atividade física regular

ABSTRACT The pattern for ambulatory electrocardiography was evaluated in 25 healthy German Shepherd dogs. The influences of gender, age, and physical activity in HR maximum, mean, and minimum (HRmx, HRme, and HRmin, respectively) were studied. The physically active dogs (PA) showed lower HRme than sedentary animals (S) (P=0.03), whereas HRmx and HRmin were not altered (P=0.06 and P=0.65, respectively). The HRme was 80.89 ± 13.85 for PA and 112.94 ± 35.71 for S. No effect of gender and age on HR was observed. It is possible to state that the physical activity can modulate the sinus node of the dogs. Keywords: dog, German Shepherd, ambulatory electrocardiography, physical activity REFERENCIAS BIBLIOGRAFICAS BILLMAN, G.E. Aerobic exercise conditioning: a nonpharmacological antiarrhythmic intervention. J. Appl. Physiol ., v.92, p.446-454, 2002. DIXON, E.M.; KAMATH, M.V.; MCCARTNEY, N. et al. Neural regulation of heart rate variability in endurance athletes and sedentary controls. Cardiovasc. Res

Alterations in peripheral circulation in dogs with cardiac tamponade

DISTURBANCES related to the pericardium have been increasingly observed in routine clinical examinations carried out on domestic animals. In dogs, pericardial effusion is commonly associated with neoplasia or idiopathic pericarditis (Stafford Johnson and others 2004). The primary pathophysiological abnormality of cardiac tamponade is an increase in intrapericardial pressure, which impairs ventricular diastolic filling, inevitably resulting in a lower stroke volume (Spodick 1998). Although echocardiography is the best method for diagnosis of pericardial effusion, the presence of fluid in the pericardium does not by itself define cardiac tamponade (Boon 1998). Duplex Doppler ultrasonography (DDU) is a non-invasive method that can estimate both quantitative and qualitative measures to evaluate peripheral blood flow disorders in animals (Fernandez del Palacio and others 2003, Lee and others 2004, Nogueira and others 2011). However, there is no description in the literature regarding the applicability of this technique in the assessment of peripheral arterial circulation in dogs with pericardial tamponade. This short communication reports clinical cases in which DDU was used as a supplementary method of diagnosing pericardial tamponade in dogs. Three boxer dogs (two females and one male) and a German shepherd dog (male), ranging from eight to 10 years of age, were studied. In all the animals, the main clinical signs were lethargy and exercise intolerance. Muffled heart sounds and a weak femoral pulse were observed in all the dogs. Mild anaemia, with signs of regeneration, was observed in the whole blood cell count. In the ECG records, a typical sinus rhythm was observed in all the dogs. Low R wave amplitude was found in …