Preliminary reference values for electrocardiography, echocardiography and myocardial morphometry in the European brown hare (Lepus europaeus)

The study aimed at defining reference values for electrocardiographic (ECG) and echocardiographic parameters as well as macroscopic dimensions of the heart and microscopic dimensions of cardiomyocytes in the European brown hare. The studies were conducted on 30 adult, clinically healthy hares of either sex caught in Poland. ECG and echocardiography were performed supravitally on anaesthetized hares. After euthanasia, gross and microscopic myocardial and cardiomyocyte dimensions were determined. Heart rate amounted to 140 ± 37.5 beats/min, the leading rhythm involved the sinus rhythm. P wave time was 26 ± 5 ms, PQ time was 80 ms, QRS time was 29 ± 3.5 ms, and ST was 97.5 ± 7 ms. Echocardiography determined a left ventricular wall end-diastolic diameter of 8.6 ± 2.0 mm and an intraventricular septum end-diastolic diameter of 5.75 ± 1.0 mm. The thickness of the interventricular septum corresponded to that of the free wall of the left ventricle, a finding consistent with physiological hypertrophy. Preliminary reference values were established for echocardiography. The findings were similar to those obtained at necropsy. The ECG and echocardiographic studies represent the first supravital examination of cardiac function in the hare. The obtained results illustrate adaptation of hare's myocardium to its mode of life. The cardiac findings resemble the athlete's heart syndrome described in humans. The findings may prove useful in further studies on the physiology of the cardio-vascular system in the hare

NT-pro-BNP and troponin I as predictors of morality in dogs with hearth failure

The purpose of this study was to develop prognostic models for heart failure in dogs with dilated cardiomyopathy (DCM). The prospective study included 26 dogs with DCM and 58 healthy dogs. The ervation time median was 250 days (1-600 days). All the dogs were clinically examined, had echocardiography, electrocardiography, and morphological and biochemical blood sampling. Twenty four deaths were found in the group of dogs with DCM and 1 demise in the healthy dog's group. There was a significant increase in the level of NT-pro-BNP and cTnI (p<0.0005) in the group of dogs with DCM and a significant higher level of NT-pro-BNP and cTnI (p<0.0005) in the dead dogs from group with DCM that died or were euthanized up to the 60'th day of observation, compared to the animals that outlasted over 60 days of observation. The median level of NT-pro-BNP in the dogs which had short survival period (no more than 60 days) was 4865 pmol/L and the median level of cTnI in the same group of dogs was 0.63 ng/ml. The median level of NT-pro-BNP in the group of dogs with DCM, which lived longer than 60 days of observation was 978 pmol/l and the median level of cTnI in this group was 0.1 ng/ml. The level of NT-pro-BNP (r=0.79) and cTnI (r=0.4) correlated with the dogs' death. NT-pro-BNP and cTnI measurements could be useful to evaluate the survival the dogs with DCM. Increased level of NT-pro-BNP and cTnI is a bad prognosis. In the performed analysis of the Cox hazard regression it was found that cTnI level has a significant impact of the survival of the dogs (HR=8.54; Cl 1.1-46.6; p=0.02)

Heart rate turbulence in mild-to-moderate aortic stenosis in boxers

Heart rate turbulence (HRT) is a new electrocardiographic parameter used in human medicine to predict the possibility of death in patients with cardiac diseases. There is no information about HRT in healthy dogs and those with cardiac diseases. The aim of the present study was to compare the HRT in healthy Boxers dogs with Boxers with mild and moderate subaortic stenosis (SAS), to disclose the relationship between HRT and specific echocardiographic parameters and to evaluate if HRT can be used as a prognostic value in dogs with aortic stenosis. The study revealed significantly lower values of turbulence onset (TO) and turbulence slope (TS) HRT dogs with SAS (TO = -0.76 ± 2.6, TS = 7.1 ± 3.21) in compared with healthy dogs (TO = -7.45 ± 9.72, TS = 14.33 ± 8.76). TO values correlated with the left ventricular mass (LVM)/body mass factor (r = 0,32; p = 0.048). Based on the results obtained it can be stated that dogs with SAS have a compromised baroreceptor response, which can influence the mortality of the animals with described cardiac defect

Heart rate turbulence in healthy dogs and dogs with dilated cardiomyopathy

Heart rate turbulence (HRT) is modulated by the baroreceptor reflex and it was suggested that it could be used as a measure of autonomic dysfunction. Impaired HRT is of a significant prognostic value in humans after myocardial infarction, suffering from dilated cardiomyopathy and patients with heart failure. So far no studies were performed assessing the importance of HRT in dogs. The aim of this study was to prospectively evaluate the HRT turbulence onset (TO) and the turbulence slope (TS) in healthy dogs and in dogs with DCM and to compare the HRT in dogs with DCM that died during the first 30 days of observation and dogs with DCM that survived the first 30 days after the HRT analysis. The current study was aimed at determining reference value of the TO and TS of HRT in healthy dogs (control group) and dogs with dilated cardiomyopathy (DCM group). The tests were carried out on 30 healthy dogs and 30 dogs with DCM composed of Boxers, Doberman pinschers and Great Danes, of different sexes and body weights from 22 to 72 kg, aged between 1.5 and 11.5 years, submitted to the 24-hour Holter monitoring. HRT parameters were calculated using an HolCard software algorithm. TO is a percentage difference between the heart rate immediately following ventricular premature complex (VPC) and the heart rate immediately preceding VPC. TS corresponds to the steepest slope of the linear regression line for each sequence of five consecutive normal intervals in the local tachogram. The average TO in healthy dogs was determined as -13.55 ± 11.12%, TS was 21.33 ± 9.66 ms/RR. TO in dogs with DCM was determined as - 2.61 ± 2.1% and TS was 6.15 ± 3.86 ms/RR. Parameters of HRT were statistically significantly decreased (p<0.01) in dogs with DCM. HRT TO and TS were statistically significantly decreased in dogs with DCM. Dogs with DCM that survived more than 30 days of observation had HRT statistically significantly decreased in comparison to dogs with DCM that died after the 30’th day of observation. Decreased HRT parameters in dogs with DCM suggest an autonomic neuropathy which principally consists of the withdrawal of the cardiac parasympathetic tone. The more the autonomic neuropathy is advanced the faster the death of the dog with DCM might occur, with no correlation with the level of the heart failure

Short-term heart rate variability in dogs with sick sinus syndrome or chronic mitral valve disease as compared to healthy controls

Heart rate variability is an established risk factor for mortality in both healthy dogs and animals with heart failure. The aim of this study was to compare short-term heart rate variability (ST-HRV) parameters from 60-min electrocardiograms in dogs with sick sinus syndrome (SSS, n=20) or chronic mitral valve disease (CMVD, n=20) and healthy controls (n=50), and to verify the clinical application of ST-HRV analysis. The study groups differed significantly in terms of both time – and frequency- domain ST-HRV parameters. In the case of dogs with SSS and healthy controls, particularly evident differences pertained to HRV parameters linked directly to the variability of R-R intervals. Lower values of standard deviation of all R-R intervals (SDNN), standard deviation of the averaged R-R intervals for all 5-min segments (SDANN), mean of the standard deviations of all R-R intervals for all 5-min segments (SDNNI) and percentage of successive R-R intervals >50 ms (pNN50) corresponded to a decrease in parasympathetic regulation of heart rate in dogs with CMVD. These findings imply that ST-HRV may be useful for the identification of dogs with SSS and for detection of dysautonomia in animals with CMVD

Short-term heart rate variability (HRV) in healthy dogs

Heart rate variability (HRV) is a well established mortality risk factor in both healthy dogs and those with heart failure. While the standards for short-term HRV analysis have been developed in humans, only reference values for HRV parameters determined from 24-hour ECG have been proposed in dogs. The aim of this study was to develop the reference values for short-term HRV parameters in a group of 50 healthy dogs of various breeds (age 4.86 ± 2.74 years, body weight 12.2 ± 3.88 kg). The ECG was recorded continuously for at least 180 min in a dark and quiet room. All electrocardiograms were inspected automatically and manually to eliminate atrial or ventricular premature complexes. Signals were transformed into a spectrum using the fast Fourier transform. The HRV parameters were measured at fixed times from 60-min ECG segments. The following time-domain parameters (ms) were analyzed: mean NN, SDNN, SDANN, SDNN index, rMSSD and pNN50. Moreover, frequency-domain parameters (Hz) were determined, including very low frequency (VLF), low frequency (LF) and high frequency (HF) components, total power (TP) and the LF/HF ratio. The results (means ± SD) were as follows: mean NN = 677.68 ± 126.89; SDNN = 208.86 ± 77.1; SDANN = 70.75 ± 30.9; SDNN index = 190.75 ± 76.12; rMSSD = 259 ± 120.17, pNN50 = 71.84 ± 13.96; VLF = 984.96 ± 327.7; LF = 1501.24 ± 736.32; HF = 5845.45 ± 2914.20; TP = 11065.31 ± 3866.87; LF/HF = 0.28 ± 0.11

Acid-base balance parameters and a value of anion gap of arterial and venous blood in Malopolski horses

The comparative study of the acid-base balance (ABB) parameters has been performed on 20 clinically healthy mature Małopolski horses. An arterial blood sample from the facial artery and a sample of venous blood from the external cervical vein were colected from each animal. In the samples tested, the blood pH, pCO₂, tCO₂, HCO₃-, concentration of Na+, K+, Cl-, and a value of the anion gap were determined. The difference among pCO₂, tCO₂, and HCO₃ - in both samples tested was statistically significant, whereas the pH of the arterial blood and the pH of the venous blood did not differ significantly. The anion gap in both types of blood did not differ significantly. Conclusions: 1) ABB parameters such as pCO₂, HCO₃-, and tCO₂ determined in the arterial and venous blood of the Małopolski horses differ from each other significantly. 2) In spite of the lack of the differences between pH of the arterial and venous blood, the ABB parameters in horses should be determined in the arterial blood, because the comparative study performed proves that the analysis of the ABB parameters determined for the venous blood of a healthy horse may lead to a wrong diagnosis of the compensated respiratory acidosis. 3) The mean value of anion gap in horses aged 8-12 years amounts to 20.9 mmol/l for the arterial blood and 19.93 for the venous blood; the difference between the two values is not statistically significant