Evidence of cardiac autonomic neuropathy in dogs with diabetes mellitus

The NeuroScope, a specific and sensitive indicator of cardiac vagal tone, was used to look for differences in autonomic tone between 25 dogs with naturally occurring diabetes mellitus and 23 healthy control dogs, to determine whether there was any correlation between the dogs' cardiac vagal tone, the duration of diabetes and the adequacy of glycaemic control. The cardiac index of parasympathetic activity (cipa) was determined for each dog over a period of 2600 heartbeats. The mean, median and modal cipa values were significantly lower in the diabetic dogs than in the healthy dogs. There was no significant relationship between the cipa values and the duration of disease or the adequacy of recent glycaemic control in the diabetic dogs, but there was a significant inverse relationship between the cipa values and the bodyweight of the diabetic dogs that was not evident in the normal dogs. The conclusions were based on a 500-heartbeat interval selected from the 2600 heartbeats recorded.     

Investigation of heart rate variability in a dog with upper respiratory tract obstruction

An eight-year-old bull mastiff presented with respiratory obstruction caused by a tumour dorsolateral to the larynx. Removal of the tumour was attempted but the dog died. A novel noninvasive measurement of heart rate variability and cardiac parasympathetic activity, recorded real-time from an electrocardiograph signal, was used to investigate cardiac rhythm in the dog. A simultaneous record of heart rate and cardiac parasympathetic activity showed severe sinus arrhythmia caused by the parasympathetic tone, in which the inspiratory heart rate exceeded 140 beats per minute (bpm) and the expiratory heart rate fell to below 60 bpm. The extent of respiratory modulation of the cardiac parasympathetic activity (vagal tone) has not been reported before using this technique on-line in a conscious, freely-behaving and spontaneously breathing animal. Non-invasive measurements of cardiac parasympathetic tone show great potential for the assessment of animals with systemic and cardiac disease including cardiac failure.     

Clinical utility of serum N-terminal pro-B-type natriuretic peptide concentration for identifying cardiac disease in dogs and assessing disease severity

OBJECTIVE: To determine whether serum N-terminal pro-B-type natriuretic (NT-proBNP) concentration could be used to identify cardiac disease in dogs and to assess disease severity in affected dogs. DESIGN: Cross-sectional study. ANIMALS:119 dogs with mitral valve disease, 18 dogs with dilated cardiomyopathy, and 40 healthy control dogs. PROCEDURES: Serum NT-proBNP concentration was measured with an ELISA validated for use in dogs. Results of physical examination, thoracic radiography, echocardiography, and serum biochemical analyses were recorded for dogs with cardiac disease. RESULTS:Serum NT-proBNP concentration was significantly higher in dogs with cardiac disease than in control dogs, and a serum NT-proBNP concentration > 445 pmol/L could be used to discriminate dogs with cardiac disease from control dogs with a sensitivity of 83.2% and specificity of 90.0%. In dogs with cardiac disease, serum NT-proBNP concentration was correlated with heart rate, respiratory rate, echocardiographic heart size, and renal function. For dogs with cardiac disease, serum NT-proBNP concentration could be used to discriminate dogs with and without radiographic evidence of cardiomegaly and dogs with and without congestive heart failure. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that serum NT-proBNP concentration may be a useful adjunct clinical test for diagnosing cardiac disease in dogs and assessing the severity of disease in dogs with cardiac disease.     

Development and evaluation of a questionnaire for assessing health-related quality of life in dogs with cardiac disease

OBJECTIVE: To develop and evaluate a questionnaire (functional evaluation of cardiac health [FETCH] questionnaire) for assessing health-related quality of life in dogs with cardiac disease. DESIGN: Prospective study. ANIMALS: 360 dogs with cardiac disease PROCEDURE: The questionnaire was developed on the basis of widely accepted clinical signs of cardiac disease in dogs. A FETCH score was calculated by summing responses to questionnaire items; possible scores ranged from 0 to 85. For questionnaire validation, owners of 60 dogs were asked to complete the questionnaire and provide an overall assessment of their dogs' quality of life (16 owners completed the questionnaire twice). Disease severity was assessed with the International Small Animal Cardiac Health Council (ISACHC) classification for cardiac disease. Following validation, the final questionnaire was administered to owners of the remaining 300 dogs. RESULTS: Internal consistency of the questionnaire was good, and the FETCH score was significantly correlated with the owner-reported quality-of-life score and with ISACHC classification. For owners that completed the questionnaire twice, scores were significantly correlated. During the second phase of the study, the FETCH score ranged from 0 to 70 (median, 7) and was significantly correlated with ISACHC classification, but did not vary significantly with underlying disease. For dogs examined twice, the change in FETCH score was significantly greater for dogs in which ISACHC classification improved than for dogs in which ISACHC classification was unchanged. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the FETCH questionnaire is a valid and reliable method for assessing health-related quality of life in dogs with cardiac disease.     

Comparison of the effects of thiopentone and propofol on the electrocardiogram of dogs

Sixty-four dogs were randomly assigned to receive either thiopentone or propofol and their electrocardiograms were recorded immediately before and shortly after they were anaesthetised. Thiopentone caused a marked increase in QT and JT intervals, a flattening of the T-wave and an increase in precordial QT dispersion. Propofol induced a less marked increase in QT and JT intervals, corrected for heart rate. Both agents induced an increase in heart rate and a decrease in heart rate variability, consistent with reduced vagal tone. Shortly after anaesthesia was induced, thiopentone affected ventricular repolarisation to a far greater extent than propofol, changes which suggest that it may be more likely to induce re-entrant ventricular arrhythmogenesis and could be associated with an increase in sympathetic tone. Propofol may therefore be more suitable than thiopentone for dogs with a susceptibility to ventricular arrhythmias or a long QT interval.     

Assessment of survey radiography as a method for diagnosis of congenital cardiac disease in dogs.

In order to assess the diagnostic accuracy of survey radiography for canine congenital cardiac anomalies, thoracic radiographs of 57 dogs with congenital cardiac anomalies, 31 normal dogs and 27 dogs with acquired cardiac disease were mixed, and reviewed by two independent observers, who were blinded to any patient information. The congenital anomalies were aortic stenosis (n=25), pulmonic stenosis (n=10), patent ductus arteriosus (n=9), ventricular septal defect (n=8), tricuspid dysplasia (n=3) and mitral dysplasia (n=2). Both observers were moderately accurate at identifying dogs with cardiac disease. Their ability to distinguish dogs with congenital versus acquired cardiac disease was poorer and this assessment was probably influenced by the recognition of patients that were skeletally immature, which biased observers towards a diagnosis of congenital cardiac anomaly. The diagnosis rate for specific congenital anomalies was also poor (the differential list included a correct diagnosis in only 40 and 37 per cent of cases). Radiographic signs of specific cardiac chamber enlargement or pulmonary vascular abnormalities were recognised by both observers in only 20 per cent of instances in which they might be expected. They were, however, recognised more frequently in dogs with anomalies that imposed a volume load on the heart than in dogs with anomalies that induced a pressure load on the organ. It is concluded that survey radiography is an inaccurate method for diagnosis of canine congenital cardiac anomalies because of the difficulty of recognising radiographic signs, which are not present in many cases.     

Use of breed-specific ranges for the vertebral heart scale as an aid to the radiographic diagnosis of cardiac disease in dogs.

The vertebral heart scale was measured on right lateral recumbent thoracic radiographs of 320 dogs of six popular breeds, including for each breed at least 20 dogs with no clinical signs of cardiovascular or respiratory disease and at least 19 dogs with cardiac or respiratory disease. There were significant differences between the mean values of the scale for the different breeds; the normal boxer dogs had a significantly higher mean value than the normal dogs of all the other breeds, and the labrador retrievers had a significantly higher mean value than all the other breeds except the boxer and the cavalier King Charles spaniel. For all the breeds except the boxer, there was a trend for dogs with cardiac disease (but not respiratory disease) to have higher mean values on the scale than normal dogs of the same breed; however, at the optimal value of the scale for distinguishing between dogs of each breed with and without cardiac disease, the sensitivity and specificity were relatively low, in the range 58 to 83 per cent. The scale was most accurate for the diagnosis of cardiac disease in the Yorkshire terrier and the cavalier King Charles spaniel, breeds affected by predominantly dilative forms of cardiac disease. In contrast, it was very inaccurate in the boxer, a breed that has a higher incidence of cardiac diseases associated with concentric hypertrophy.     

Measurement of plasma atrial natriuretic peptide as an indicator of prognosis in dogs with cardiac disease

Twenty-three dogs with heart failure were evaluated in a 12-month study by measuring baseline plasma atrial natriuretic peptide (ANP) concentrations. Ten dogs were classified as having mild to moderate cardiac disease (group 1) and 13 dogs were classified as having severe cardiac disease (group 2). The mean plasma ANP concentration for the group 1 dogs was 64 +/- 45 pg/mL and for the group 2 dogs, 328 +/- 122 pg/mL. The median survival time (1,095 d) for group 1 dogs was significantly greater (P < 0.05) than for group 2 dogs (58 d). A significantly (P < 0.05) greater median survival was noted for dogs with plasma ANP < 95 pg/mL (1095 d) compared with those with ANP > 95 pg/mL (58 d). Plasma ANP concentrations are a potential noninvasive predictor of survival in dogs with heart failure.     

Serum nitrate and nitrite in dogs with spontaneous cardiac disease

The purpose of this study was to determine whether nitric oxide (NO) concentrations are high in dogs with chronic valvular disease (CVD) and dilated cardiomyopathy (DCM) compared to healthy controls and to determine whether NO concentrations are correlated with type of cardiac disease, disease severity, medical therapy, or serum tumor necrosis factor (TNF) and interleukin-1 (IL-1). Blood was collected from 32 dogs with DCM, from 10 dogs with CVD, and from 10 healthy controls. Indirect determination of NO concentrations was performed by a commercial photoabsorbance assay that uses a Greiss reagent to measure the concentration of nitrite and nitrate (NN), end products of NO metabolism. TNF and IL-1 activities were measured by bioassay. Mean NN concentrations were significantly higher in dogs with heart disease (median, 4.57 microM; range, 0.00-31.05 microM) than in controls (median, 0.00 microM; range, 0.00-6.16 microM; P = .04). NN concentrations in dogs with cardiac disease were not correlated with type or severity of cardiac disease, medication type, or TNF and IL-1 concentrations. NN concentrations were inversely correlated with fractional shortening. The results of this study suggest that metabolites of NO are increased in some dogs with cardiac disease, but these increases appear to be independent of disease severity, TNF and IL-1 concentrations, and type of pharmacologic intervention.     

Assessment of the value of the vertebral heart scale in the radiographic diagnosis of cardiac disease in dogs

In order to assess the influence of the vertebral heart scale (VHS) on the accuracy of the radiographic diagnosis of cardiac disease, thoracic radiographs of 50 dogs with proven cardiac disease, 26 with other thoracic diseases, and 50 with no clinical signs of cardiovascular or respiratory disease were mixed and examined by three independent, blinded observers chosen to represent a range of radiographic abilities. They first examined all the radiographs without making measurements of VHS and made a diagnosis. They then re-examined the radiographs, and measured VHS on both lateral and dorsoventral or ventrodorsal radiographs before again recording a diagnosis without reference to their original diagnoses. For all the observers, the dogs with cardiac disease had a higher mean VHS than the normal dogs. A VHS over 10.7 on the lateral radiograph was a moderately accurate sign of cardiac disease. The observers' accuracy of diagnosis did not change significantly as a result of using VHS as an adjunct to a subjective assessment of the radiographs.     

Cardiac troponin-I concentration in dogs with cardiac disease

Cardiac troponin-I (cTnI) is a highly sensitive and specific marker of myocardial injury and can be detected in plasma by immunoassay techniques. The purpose of this study was to establish a reference range for plasma cTnI in a population of healthy dogs using a human immunoassay system and to determine whether plasma cTnI concentrations were high in dogs with acquired or congenital heart disease, specifically cardiomyopathy (CM), degenerative mitral valve disease (MVD), and subvalvular aortic stenosis (SAS). In total, 269 dogs were examined by physical examination, electrocardiography, echocardiography, and plasma cTnI assay. In 176 healthy dogs, median cTnI was 0.03 ng/mL (upper 95th percentile = 0.11 ng/mL). Compared with the healthy population, median plasma cTnI was increased in dogs with CM (0.14 ng/mL; range, 0.03-1.88 ng/mL; P < .001; n = 26), in dogs with MVD (0.11 ng/mL; range, 0.01-9.53 ng/mL; P < .001; n = 37), and in dogs with SAS (0.08 ng/mL; range, 0.01-0.94 ng/mL; P < .001; n = 30). In dogs with CM and MVD, plasma cTnI was correlated with left ventricular and left atrial size. In dogs with SAS, cTnI demonstrated a modest correlation with ventricular wall thickness. In dogs with CM, the median survival time of those with cTnI >0.20 ng/mL was significantly shorter than median survival time of those with cTnI <0.20 ng/mL (112 days versus 357 days; P = .006). Plasma cTnI is high in dogs with cardiac disease, correlates with heart size and survival, and can be used as a blood-based biomarker of cardiac disease.     

Canine hypertrophic cardiomyopathy.

Necropsy findings in 10 dogs with naturally occurring cardiac disease closely resembled hypertrophic cardiomyopathy in human beings and cats. Each dog had marked cardiac hypertrophy, and 8 dogs had disproportionate thickening of the ventricular septum with respect to the left ventricular free wall (compared with dogs with normal hearts or with cardiac hypertrophy due to acquired or congenital heart disease). Ratios of septum to free wall thickness in the 10 dogs ranged from 1.1 to 1.5, and 6 had ratios greater than or equal to 1.3. Marked cardiac muscle cell disorganization in the ventricular septum, characteristic of human patients with hypertrophic cardiomyopathy, was found in only 2 of the 10 dogs. Death occurred while the dogs were under anesthesia during the course of operative procedures (5 dogs) or unexpectedly in animals without previous manifestations of cardiac disease (3 dogs). Four dogs had clinical signs of congestive heart failure, including 2 with marked cardiac decompensation. Two of these 4 dogs with heart failure and 1 dog that died during unrelated surgery, but without prior signs of heart disease, had electrocardiographic evidence of complete heart block.     

Clinical usefulness of cardiac event recording in dogs and cats examined because of syncope, episodic collapse, or intermittent weakness: 60 cases (1997-1999)

OBJECTIVE: To determine the clinical usefulness of cardiac event recording in evaluating dogs and cats with unexplained syncope, episodic collapse, or intermittent weakness. DESIGN: Retrospective study. ANIMALS: 58 dogs and 2 cats. PROCEDURE: Medical records and electrocardiographic rhythm strips obtained by cardiac event recordings were reviewed. Cardiac rhythm data from the event recordings were classified as diagnostic or nondiagnostic. Diagnostic yield was calculated by dividing the number of animals for which cardiac event recording was diagnostic by the total number of animals undergoing cardiac event recording. RESULTS: For 51 animals, cardiac event recording was classified as diagnostic; therefore, overall diagnostic yield was 85%. Diagnostic yield was lower for animals without underlying structural heart disease (75.5%) than for animals with structural heart disease (95.6%). A specific arrhythmia was identified as the cause of clinical signs in 18 of the 51 (35%) animals for which cardiac event recording was diagnostic. Cardiac arrhythmia was definitively excluded as the cause of clinical signs in the remaining 33 (65%) animals in which cardiac event recording was diagnostic. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that cardiac event recording had a high diagnostic yield in dogs and cats examined because of unexplained syncope, episodic collapse, or transient weakness and ataxia, regardless of whether animals did or did not have an underlying structural heart disease. Diagnostic yield of cardiac event recording was higher than that reported previously for Holter monitoring.     

Spectral analysis of circadian rhythms in heart rate variability of dogs

OBJECTIVE: To determine characteristics of power spectral analysis of heart rate variability (HRV) during a 24-hour period in dogs and to evaluate the effects of vagal and sympathetic tone on HRV ANIMALS: 16 healthy adult Beagles. PROCEDURE: Power spectral analysis of HRV was conducted, using 24-hour ambulatory ECG recordings. Circadian rhythms were evaluated in terms of absolute units of low-frequency (LF) and high-frequency (HF) powers, their ratio (LF:HF), and their adjusted (normalized) units (LF[norm] and HF[norm]). Three or 4 dogs were used for simultaneous measurement of heart rate and respiratory waveform as well as to evaluate treatment (propranolol, atropine, or both) administered to cause blockade of the autonomic nervous system. RESULTS: Values for LF and HF powers, LF:HF, LF(norm), and HF(norm) had obvious rhythmicity in clinically normal dogs. The HF power of HRV in dogs was extremely high, compared with that of other species, and HF peaks corresponded to peaks obtained from respiratory waveforms. Blockade of the autonomic nervous system documented that HRV in dogs was mostly attributable to vagal activity. CONCLUSION AND CLINICAL RELEVANCE: We determined characteristics of power spectral analysis of HRV in dogs, including circadian rhythm of the autonomic nervous system. Power spectral analysis of HRV may provide a useful noninvasive technique for assessing the effect of drugs on activity of the autonomic nervous system in dogs.     

Diagnosis and treatment of cardiac arrhythmias

Cardiac arrhythmias are probably more common in horses than in any other domestic animal species. The most frequent clinical complaint associated with cardiac arrhythmias is exercise intolerance. Physical examination is characterized by auscultation abnormalities such as fast or slow heart rate, irregular rhythm, extra sounds, long pauses, or abnormal heart sounds. The electrocardiogram is used to make a definitive diagnosis of the dysrhythmia. Other laboratory and cardiac function tests are employed to determine the etiology and to assess the significance of the arrhythmia. Antiarrhythmic therapy is given when clinical signs specifically related to the arrhythmia are present, when hemodynamic parameters are compromised by the arrhythmia, or when the ECG reveals abnormalities that put the patient at risk for development of more severe arrhythmias. The cardiovascular drugs most frequently used are digoxin and quinidine. Digoxin is most commonly used for supraventricular arrhythmias, especially arrhythmias characterized by fast heart rates. Quinidine is very effective for short-term treatment of ventricular and supraventricular arrhythmias but must be used with caution because of the potential for toxic side effects. The cardiac arrhythmias due to vagal tone (sinus arrhythmia, sinus block, sinus arrest, sinus bradycardia, wandering pacemaker, first-degree AV block, and second-degree AV block) that are found in resting horses are generally considered to be normal and generally do not require therapy.     

Hemodynamic Effects of Atropine and Glycopyrrolate in Isoflurane-Xylazine-Anesthetlzed Dogs

Alterations in parasympathetic tone are partially responsible for xylazine's hemodynamic effects. The purpose of this study was to evaluate and compare the hemodynamic changes caused by the administration of intravenous (IV) atropine or glycopyrrolate after IV xylazine in isoflurane-anesthetized dogs. Six healthy beagles (8.2 to 10.7 kg) were used in two trials separated by 7 days. Anesthesia was induced and maintained with isoflurane in 100% oxygen with controlled ventilation. Once constant end-tidal isoflurane (1.8%) and arterial partial pressure of carbon dioxide (35 to 45 mm Hg) values were reached, baseline data were recorded and xylazine (0.5 mg/kg, IV) was given. In trial 1 atropine (0.1 mg/kg, IV) was given 5 minutes after xylazine, and in trial 2 glycopyrrolate (0.025, mg/kg, IV), was given 5 minutes after xylazine. Hemodynamic variables were recorded 3 minutes after xylazine and 3 minutes after anticholinergic administration. In trial 2, bilateral vagotomies were performed 10 minutes after glycopyrrolate, and hemodynamic variables were recorded 3 minutes later. Heart rate, cardiac index, and stroke index decreased; arterial pressure and systemic vascular resistance increased after xylazine. Heart rate, cardiac index, and rate pressure product increased after anticholinergic administration. Significant differences between atropine and glycopyrrolate were not observed in any of the hemodynamic parameters. Similarly, significant differences between glycopyrrolate and bilateral vagotomy were not observed. The authors conclude that intravenous atropine and glycopyrrolate have equivalent hemodynamic actions during the increased pressure phase after IV xylazine in isoflurane-anesthetized dogs; that intravenous atropine and glycopyrrolate produce comparable increases in heart rate and that both may increase the risk of myocardial hypoxia associated with an increase in rate pressure product; and that vagal blockade produced by high-dose glycopyrrolate (.025 mg/kg, IV) is similar to that produced by bilateral vagotomy.     

Analytical validation and clinical evaluation of a commercially available high-sensitivity immunoassay for the measurement of troponin I in humans for use in dogs

ObjectiveTo analytically validate a commercially available high-sensitivity immunoassay for measurement of cardiac troponin I (cTnI) in humans for use in dogs and to evaluate serum cTnI concentrations in healthy dogs and 3 well-defined groups of dogs with common cardiac diseases.AnimalsCanine serum samples were used for validation. 85 client-owned dogs including 24 healthy controls, 20 with myxomatous mitral valve disease, 19 with congenital heart disease, and 22 with arrhythmias.MethodsFour serum samples were used to analytically validate the ADVIA Centaur TnI-Ultra assay by assessing intra-assay variability, inter-assay variability, spiking recovery, and dilutional parallelism. Dogs were grouped based on examination, echocardiography, and additional testing as clinically indicated, and serum cTnI concentrations were compared.ResultsAnalysis of the serum samples used for validation revealed an intra-assay coefficient of variation between 3.6% and 5.7%, and an inter-assay coefficient of variation between 2.4% and 5.9%. Observed to expected ratios for spiking recovery were 97.9 ± 8.6% (mean, SD). Observed to expected ratios for dilutional parallelism were 73.0 ± 11.5% (mean, SD). Dogs with cardiac disease had significantly higher serum cTnI concentrations (P < 0.005) than healthy dogs.ConclusionsThe ADVIA Centaur TnI-Ultra's low limit of detection allows measurement of serum cTnI in the majority of dogs even with no or mild cardiac disease. Dilution of samples for measurement of values above the upper limit of detection is not reliable and therefore not recommended. Serum cTnI concentrations are significantly higher in dogs with cardiac disease compared to healthy dogs.     

Evaluation of dietary patterns in dogs with cardiac disease

OBJECTIVE: To determine the dietary patterns and intake of nutrients of concern in dogs with cardiac disease. DESIGN: Prospective study. ANIMALS: 82 dogs with dilated cardiomyopathy (DCM) or chronic valvular disease. PROCEDURE: Owners of dogs were contacted and given a standardized telephone questionnaire regarding diet and a 24-hour food recall to determine daily intake of calories, protein, fat, sodium, potassium, and magnesium. RESULTS: Among the 82 dogs, 71% had no congestive heart failure (CHF), and 29% had CHF or a history of CHF. Sixty-one percent of dogs had concurrent diseases. Anorexia was or had been evident in 34% of dogs and was significantly more common in the CHF group and in dogs with DCM. Most dogs (92%) received some treats and table food, with a median percentage of daily calories from treats of 19% (range, 0% to 100%). Most owners (57%) that administered pills used human or pet foods for pill administration. Most dogs ate more than the Association of American Feed Control Officials (AAFCO) minimum values for fat and protein. Daily sodium intake varied from 14 to 384 mg/100 kcal, compared with the AAFCO minimum of 17 mg/100 kcal. A median of 25% of total daily sodium came from treats and table food (range, 0% to 100%). Dogs with CHF ate significantly more sodium, compared with dogs with no CHF. CONCLUSIONS AND CLINICAL RELEVANCE: Dietary intake for dogs with cardiac disease is highly variable and often not optimal.     

Evaluation of circulating amino terminal-pro-B-type natriuretic peptide concentration in dogs with respiratory distress attributable to congestive heart failure or primary pulmonary disease

OBJECTIVE: To evaluate assessment of circulating amino terminal-pro-B-type natriuretic peptide (NT-proBNP) concentration as a means to discriminate between congestive heart failure and primary pulmonary disease in dogs. DESIGN: Prospective case series. ANIMALS: 46 dogs with signs of respiratory distress or coughing. PROCEDURES: All dogs underwent physical and thoracic radiographic examinations. Dogs with evidence of heart disease (eg, murmur, arrhythmia, or large cardiac silhouette detected by radiography) also underwent echocardiography. Dogs with no evidence of heart disease or failure were included if they underwent bronchoalveolar lavage (with cytologic examination and bacterial culture of the lavage fluid). Blood samples for NT-proBNP assay were obtained within 12 hours of the diagnosis of heart failure or prior to bronchoalveolar lavage in dogs with primary pulmonary disease. Circulating concentrations of NT-proBNP were compared between groups and correlated with radiographic and echocardiographic measures of cardiac size. RESULTS: Congestive heart failure and primary pulmonary disease were diagnosed in 25 and 21 dogs, respectively. Dogs with congestive heart failure had significantly higher median serum or plasma NT-proBNP concentration (2,554 pmol/L; interquartile [25% to 75%] range, 1,651.5 to 3,475.5 pmol/L) than dogs with primary pulmonary disease (357 pmol/L; interquartile range, 192.5 to 565.5 pmol/L). Radiographic vertebral heart score and echocardiographic left atrial-to-aortic diameter ratio were not correlated with NT-proBNP concentration. Left ventricular end-diastolic diameter (measured echocardiographically) and NT-proBNP concentration were weakly correlated. CONCLUSIONS AND CLINICAL RELEVANCE: Serum or plasma NT-proBNP concentration assessment may be useful for discrimination of congestive heart failure from primary pulmonary disease in dogs with respiratory distress or cough.     

Behavioral and cardiac responses by dogs to physical human–dog contact

Measures of behavioral responses and cardiovascular parameters to evaluate and assess animal well-being are well established. A major aspect of companion animal well-being seems to originate from direct human–animal interaction. For pet dogs, the manner in which they obtain and respond to petting and hugs could interfere with the development of a pleasant human–dog companionship. Therefore, the purpose of this study was to evaluate cardiovascular responses by dogs to physical human–dog contact and to assess these physiological responses in relation to the dogs' behavioral responses. Noninvasive measurements of privately owned dogs' (N = 28) cardiovascular parameters and behavioral responses were carried out during 9 physical human–dog interactions (e.g., petting the dog on its back, holding a forepaw of the dog). The behavioral responses were grouped in categories, for example, redirected behavior, displacement activity, and appeasement gesture. The mean heart rate (HR) and 2 cardiac activity parameters, standard deviation of normal-to-normal R–R intervals (SDNN) and root mean square of successive heartbeat interval differences/SDNN (RMSSD/SDNN) ratio, differed significantly among the human–dog interactions. Petting and holding the dog around the head was associated with an increased SDNN. An increased vagal tone was the dogs' responses to being petted at the chest. Displacement activities correlated negatively with all cardiovascular parameters (HR, SDNN, RMSSD, and RMSSD/SDNN ratio). Appeasement gestures were positively correlated with HR and occurred less under an increased vagal tone. The behavioral strategies, that is, freezing (standing motionless with all legs on the floor) and withdrawal (moving backward without any agonistic display) were negatively associated with the cardiac activity parameters, RMSSD and RMSSD/SDNN ratio. The dogs' behavioral and physiological responses suggest that some common physical human–dog interactions perceived as unpleasant by dogs. Emphasis on human signaling in human–dog interactions encourages development of recommendations for pleasant and safe human–dog contact to enhance dogs' well-being and the human–dog relationship.