Electrocardiographic reference values in whippets

Evaluation of the association between electrocardiogram parameters and left cardiac remodeling in dogs with myxomatous mitral valve disease

Background and Aim: Electrocardiography (ECG) is an adjunct for cardiac enlargement diagnosis. However, its efficacy in assessing left cardiac remodeling (left atrial and left ventricular enlargement) in dogs with myxomatous mitral valve disease (MMVD) remains unclear. This study aimed to evaluate the association between ECG parameters and left cardiac remodeling and to investigate whether the rate of change in ECG waveforms in the same individual reflected left cardiac remodeling in dogs with MMVD. Materials and Methods: This retrospective study included 20 healthy dogs and 140 dogs with MMVD. Data on clinical variables were obtained through physical examination, thoracic radiography, and echocardiography. The ECG parameters were the P-wave duration, PR interval, QRS complex duration, P-wave amplitude, R-wave amplitude, and mean electrical axis. Dogs with examination data that could be obtained multiple times during the study period were classified into the non-progressive and progressive groups. Results: Only the P-wave and QRS complex durations were selected as significant variables associated with imaging test parameters (p < 0.05); they had a relatively higher discriminatory ability for the left cardiac remodeling than other ECG parameters. The rates of change in the PR interval and R-wave amplitude were significantly higher in the progressive group than in the non-progressive group. Conclusion: In dogs with MMVD, the P-wave and QRS complex durations were significantly correlated with the left cardiac remodeling indicators. Furthermore, an increased rate of change in the PR interval and R-wave amplitude in the same individual may indicate left cardiac remodeling.

Left shift of the ventricular mean electrical axis in healthy Doberman Pinschers

In canine electrocardiography, the reference interval of the ventricular mean electrical axis (MEA) is between +40° and +100°. MEA values in dogs can be influenced by the patient position as well as by the shape of the thorax. The aim of this study was to evaluate the MEA in healthy Doberman Pinschers, hypothesizing that some present a left shift of the MEA. In this retrospective study, 41 healthy, client-owned Doberman Pinschers were included. Echocardiography and standard six-lead ECG examination were performed in all dogs. The MEA was calculated using the isoelectric method. The morphology of the QRS complex and the Q/R ratio in lead II were also evaluated. The median MEA was +45° and ranged from −45° to +90°. MEA was deviated in 16/41 dogs (39%), all presenting a left axis deviation (range, −45° to + 30°). Age was significantly associated with the MEA (P=0.008), showing a negative linear correlation. A deep Q wave in lead II was present in 26/41 (63%) dogs. The Q/R ratio was higher in dogs presenting left shift of the MEA (0.66; range, 0.28–1.35) in comparison to dogs with a MEA within reference range (0.44; range, 0.04–0.73; P<0.001). In conclusion, a significant number of healthy Doberman Pinschers present a left shift of the MEA compare to the reference range, and dogs with MEA deviation show a higher Q/R ratio in lead II. This data should be considered when electrocardiographic evaluation is performed in Doberman Pinschers.

Electrocardiographic reference values for healthy Netherland Dwarf rabbits and the influence of body position, age and gender

<p>The aim of this study was to provide reference values for a single, popular breed of pet rabbit. Moreover, additional objectives were to determine whether sex, body position or age alter Netherland Dwarf rabbit electrocardiographic variables and whether the use of electrocardiographic filters affects those variables. Forty Netherland Dwarf rabbits were examined clinically and standard six-lead electrocardiograms (ECGs) were recorded in sternal and then dorsal recumbency. At first power-line and anti-drift filters were used and then they were disabled. The following variables were measured in lead II: heart rate; P wave duration and amplitude; P-R interval; QRS duration; R wave amplitude (with and without filters); Q-T interval; T wave duration and amplitude; S-T segment; J-T duration; and mean electrical axis (MEA) (with and without filters). MEA was determined by 3 different methods. After statistical processing of the data, our results showed that there were no significant differences between both recumbencies, with the exception of the J-T duration, which was higher in dorsal recumbency. The R wave amplitude using electrocardiographic filters showed significant differences between males (0.083 mV) and females (0.115 mV; P&lt;0.05); and between younger rabbits (0.108 mV) and older rabbits (0.097 mV; P&lt;0.05). These differences were not shown between R waves with filters disabled. Moreover, the strongest correlation was between 2 MEA methods without filters. MEA was more leftward in the pet rabbit than in other species (dog or cats). In conclusion, electrocardiography recording without electrocardiographic filters should be assessed when it is possible, and the specific ECGs characteristics for Netherland Dwarf rabbit should be taken into account.</p>

Effects of resistance training on electrocardiographic and blood parameters of police dogs

The aims of this study were to evaluate effects of a 6 week resistance training on electrocardiographic (ECG) and blood parameters of police dogs. Our hypothesis was that this training protocol improves fitness, contributing to the welfare of these animals. Nine dogs, 18.56±0.53 months old, were evaluated before (M1) and six weeks after (M2) a training protocol using treadmill. Their training program was performed 2 times/week, and included 20 min of treadmill activity on a speed compatible with 60-80% of HRmax on weeks 1 and 2, same exercise of weeks 1 and 2 with a 5% grade added between 7.5 and 12.5 min in weeks 3 and 4, and, finally, same exercise of weeks 3 and 4 with three short bursts of strenuous exercise, 60 min after the end of treadmill activity. On both moments, animals were examined before (T0) and after (T1) an incremental effort test, and at 30 (T2) and 120 min (T3) of recovery, measuring heart rate, respiratory rate and body temperature. Blood samples were taken to determine erythrogram, aspartate aminotransferase, creatine kinase, triglycerides, lactate and glucose. Electrocardiographic variables were analysed at T0 and T1. All variables were analysed by one-way ANOVA and Tukey tests, with P≤0.05. After training, there was an increase on the length of work on treadmill of 41.5% for the German Shepherd (P=0.0139) and 21.4% for the Belgian Malinois (P=0.0085) along with a increase of maximal speed of 34.0% for the German Shepherd (P=0.0084) and 15.9% for the Belgian Malinois (P=0.0241). It was observed in physiological, blood and ECG parameters differences between M1 and M2 (P<0.05). Other findings included a lower rest QTc value at T0 after training (P=0.0194). The chosen training led to a better fitness of the police dogs as all of them worked more intensively with a low cardiovascular requirement in M2. In conclusion, current exercise protocol in a treadmill improved dogs fitness, when we analysed ECG, physiological and blood parameters, making possible that animals may be used in more extended and multiple missions, contributing welfare of these animals.

Effect of body position on electrocardiographic recordings in dogs

OBJECTIVE

To determine whether body position (standing vs right lateral recumbency) altered the quality of the electrocardiogram (ECG) and value of ECG variables in dogs when the ECG was recorded using American Heart Association guidelines for frequency response.

DESIGN

Crossover study using a convenience sample.

METHODS

ECGs were recorded twice in 65 sled dogs in random order with each dog standing or placed in right lateral recumbency. Lead II and three semi-orthogonal leads (I, aVF, and V10 ) were recorded and muscle tremor artefact was assessed.

RESULTS

Lead II ECGs obtained from dogs in right lateral recumbency had less muscle tremor artefact and consequently a shorter QRS duration than ECGs obtained with the dogs standing. The P, Q, R and S wave amplitudes differed in selected leads and the mean electrical axis was shifted 20° to the right when dogs were in right lateral recumbency.

CONCLUSIONS

Right lateral recumbency improves the quality of ECG recording in dogs by decreasing muscle tremor artefact, alters the amplitude of P, R and S waves in specific leads and results in a rightward shift in the mean electrical axis, relative to standing.