Brain natriuretic peptide concentration in dogs with heart disease and congestive heart failure

Diagnostic value of atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP) and their correlation with lipoproteins in dogs with myxomatous mitral valve disease

BACKGROUND

Myxomatous mitral valve disease (MMVD) is the most common diagnosed cardiovascular disease in dogs. Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) tests are used to diagnose congestive heart failure, but there are conflicting reports about their value in diagnosing the subclinical stages of MMVD in dogs. Moreover, the diagnostic value of blood lipoproteins in dogs with MMVD is still unclear. The purpose of this study was to assess the serum concentrations of ANP, BNP and lipoproteins of dogs with MMVD and to evaluate the correlation of the levels of ANP and BNP with lipoproteins.

RESULTS

This study was performed on 24 dogs with MMVD and 10 healthy dogs. Dogs with MMVD were classified in to stages B1 (n = 11), B2 (n = 6), C (n = 4) and D (n = 3) groups according to the classification suggested by American College of Veterinary Internal Medicine guidelines. Our results showed that the mean serum BNP levels were significantly increased for all MMVD groups compared to control dogs. The mean serum ANP levels for the stage B2, C and D groups were significantly higher than the control group, while the mean serum ANP concentrations did not differ significantly between the stage B1 and control groups. An increase in BNP level was observed in 87.5% of patients. Although BNP concentrations were elevated in 100% of dogs with stages C, D and B2, high BNP was observed in 72.72% of dogs with stage B1. Regarding ANP, 58.33% of patients had an increase in ANP. However, elevated ANP levels were found in only 27.27% of patients in stage B1, while increased ANP levels were observed in 66.66 and 100% of patients in stage B2 and C/D groups respectively. Also, in all patients with MMVD, the mean serum concentrations of high-density lipoprotein cholesterol (HDL-C) were approximately 1.7 to 2 times significantly lower than the control group. Additionally, the mean serum low-density lipoprotein cholesterol (LDL-C) increased significantly (1.9-2.7 times) compared to the control group. There was a significant inverse correlation between HDL-C and BNP, and HDL-C and ANP. LDL-C showed a significant positive correlation with BNP, and ANP. Also, LDL-C, but not HDL-C, had a significant positive correlation with LA/AO ratio, LVIDd, LVIDdN and VHS. BNP and ANP showed a significant positive correlation with LA/AO, LVIDd, LVIDdN and VHS.

CONCLUSIONS

Serum BNP has a greater diagnostic value than serum ANP in dogs with MMVD. In addition, serum BNP can be used to determine the subclinical stages of B1 and B2 MMVD. This study also suggests that dogs with subclinical MMVD, showed an increase in BNP along with a decrease in HDL-C and an increase in LDL-C, which are known to be risk factors for cardiovascular diseases in human. However, it seems that high LDL-C is more involved in the pathogenesis of MMVD than low HDL-C. Therefore, periodic testing of serum lipoproteins is recommended in high-risk patients, even if total cholesterol levels are normal.

Evaluation of new and old biomarkers in dogs with degenerative mitral valve disease

Background

Dogs with degenerative mitral valve disease are commonly presented to small animal clinicians. Diagnosis, clinical staging, and therapeutic design are based on a combination of clinical examination, radiography, and echocardiography. To support diagnosis and clinical monitoring, a multi-marker-based approach would be conceivable. The aim of this study was to investigate the suitability of Galectin-3 and interleukin-1 receptor-like 1 protein (ST2) in dogs with degenerative mitral valve disease in accordance with N-terminal-prohormone-B-type natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI). For this purpose, serum concentrations of Galectin-3 and ST2 of 64 dogs with different stages of mitral valve disease and 21 dogs without cardiac disease were analyzed at the first examination and six months later. Echocardiography, blood cell count and clinical chemistry were performed and established biomarkers NT-proBNP and cTnI were measured additionally. Differences in the biomarker concentrations between all groups at both timepoints and the change in biomarker concentrations from first to second evaluation was investigated. Furthermore, correlations of each biomarker, between biomarkers and echocardiographic measurements, were calculated. Finally, the receiver-operating characteristic curve and the area under the curve analysis were performed to differentiate between disease stages and controls.

Results

Serum concentrations of Galectin-3 and ST2 were not statistically different between canine patients in the respective stages of mitral valve disease or in comparison to dogs in the control group at any timepoint. A significant increase in ST2 concentrations from the baseline to the follow-up examination was observed in dogs classified as stage B1 and the control group. The concentrations of NT-proBNP and cTnI in stage C dogs were significantly increased in comparison to the other groups.

Conclusions

In this study, no relation between Galectin-3 and ST2 levels to the presence or stage of mitral valve disease could be detected. Nevertheless, considering the increase in ST2 concentrations from the first to second measurement, its value on monitoring disease progress could be feasible. In agreement with previous studies, NT-proBNP and cTnI have once more proven their utility in assessing disease severity. The approach of examining new cardiac biomarkers in dogs is still worth pursuing.

Short-Term Effects of Sacubitrilvalsartan on Echocardiographic Parameters in Dogs With Symptomatic Myxomatous Mitral Valve Disease

Background and Objective: Sacubitril/valsartan (SV) is an angiotensin receptor-neprilysin inhibitor that works by inhibiting the neprilysin enzyme as well as blocking angiotensin receptors. The benefits of using SV in congestive heart failure patients has been demonstrated in several clinical trials; however, limited data are available for dogs with heart failure. The aim of this study was to investigate the short-term effects of SV in comparison with ramipril in the standard therapy of symptomatic dogs suffering from myxomatous mitral valve disease (MMVD).

Methods: In this prospective, randomized, single-blind study, 21 dogs with MMVD stage C were randomly assigned to received SV (20 mg/kg orally twice a day) or ramipril (0.125 mg/kg, orally once a day) in addition to pimobendan and furosemide. Echocardiography, electrocardiography, blood pressure, N-terminal pro-B-type natriuretic peptide (NT-proBNP), and urinary aldosterone per creatinine ratio were obtained at baseline (D0) and at follow-up (4 weeks).

Results: When comparing the percent change from baseline between groups, the left atrium to aortic root ratio (LA/Ao) and left ventricular internal diameter diastole normalized to body weight (LVIDDN) were significantly reduced in the SV group (P < 0.001 and P < 0.01, respectively). The end-diastolic volume index (EDVI), end-systolic volume index (ESVI), and stroke volume were lower in the SV group (P < 0.001, P < 0.05, and P < 0.01, respectively). No changes were observed between groups for NTproBNP, blood pressure, ECG parameters, and urinary aldosterone per creatinine ratio.

Conclusion: The current study suggested that the short-term effects of SV can reverse myocardial remodeling, as inferred from several echocardiographic indices (i.e., the reduction in LA/Ao, LVIDDN, EDVI and ESVI) in dogs with MMVD stage C. These findings would support the use of SV in clinically symptomatic heart failure in dogs.

Comparison of N-terminal pro-atrial natriuretic peptide and three cardiac biomarkers for discriminatory ability of clinical stage in dogs with myxomatous mitral valve disease

Plasma N-terminal pro-atrial natriuretic peptide (NT-proANP) concentration increases with progression of myxomatous mitral valve disease (MMVD) in dogs. This multicentre, prospective study compared plasma NT-proANP, N-terminal pro-brain natriuretic peptide (NT-proBNP), ANP, and cardiac troponin I (cTnI) concentrations in dogs with MMVD for their characteristics and discriminatory ability to detect cardiac dilatation and congestive heart failure (CHF). Thirty-six healthy dogs and 69 dogs with MMVD were included. Clinical variables were obtained via physical examination, thoracic radiography, and echocardiography. The discriminatory ability of each cardiac biomarker (CB) to determine the presence or absence of cardiac dilatation (event 1) and CHF (event 2) was evaluated using the receiver operating characteristic curves. Plasma NT-proANP, NT-proBNP, and ANP concentrations showed a significant association with the left atrium/aorta ratio (P<0.01). The area under the curve of plasma NT-proANP and NT-proBNP concentrations were 0.72 and 0.75, respectively in event1 and 0.72 and 0.76, respectively in event2. Plasma NT-proANP and NT-proBNP concentrations showed sensitivity 80.0 and 80.0%; specificity 67.6 and 64.7% in event1 (cutoff value; 8,497.81 pg/ml and 1,453.00 pmol/l, respectively) and sensitivity 85.7 and 81.0%; specificity 60.4 and 64.6% in event2 (cutoff value; 8,684.33 pg/ml and 1,772.00 pmol/l, respectively). In dogs with MMVD, plasma NT-proANP, NT-proBNP, and ANP concentrations increase with left atrial enlargement. Particularly, plasma NT-proANP and NT-proBNP concentrations appeared to be equally useful in the discriminatory ability to detect cardiac dilatation and CHF.

Avaliação dos níveis plasmáticos do peptídeo natriurético NT-proBNP em cães da raça Poodle em diferentes estágios da doença valvar crônica mitral

RESUMO A doença valvar crônica mitral (DVCM) é comum em cães e pode não causar sintomas clínicos da insuficiência cardíaca (IC) durante anos. O peptídeo natriurético tipo B (BNP) é armazenado nos miócitos ventriculares e secretado para circulação com seu fragmento NT-proBNP, quando ocorre aumento. Este estudo avaliou os níveis plasmáticos do peptídeo natriurético NT-proBNP em cães da raça Poodle em diferentes estágios da DVCM, seguindo as diretrizes do American College of Veterinary Internal Medicine (ACVIM, 2009). Amostras de sangue foram coletadas para determinação do biomarcador NT-proBNP para comparação entre grupos. As medianas do NT-proBNP nos grupos estudados foram: 551pmol/L (controle), 302pmol/L (grupo B1), 1.033pmol/L (grupo B2), 954pmol/L (grupo C) e 5.541pmol/L (grupo D). Mediante o uso de um ponto de corte ideal de >709pmol/L, foi possível identificar os cães com aumento cardíaco verdadeiro daqueles sem aumento cardíaco, com sensibilidade de 75% e especificidade de 100%. O NT-proBNP aumentou de acordo com o avanço dos estágios da DVCM, sendo os estágios B2, C e D aqueles com valores mais elevados desse biomarcador. Para o estágio B2, a mensuração do NT-proBNP mostrou ser uma excelente ferramenta para diagnosticar precocemente o aumento cardíaco em cães da raça Poodle.

Assessment of Lung Ultrasound B-Lines in Dogs with Different Stages of Chronic Valvular Heart Disease

Background

In dogs with chronic valvular heart disease (CVHD), early recognition of pulmonary edema (PE) is of paramount importance. Recent studies in dogs showed that lung ultrasound examination (LUS) is a useful technique to diagnose cardiogenic PE.

Objectives

To describe LUS features in dogs with different stages of CVHD, and to determine its diagnostic accuracy in detecting PE using thoracic radiography as the reference standard.

Animals

Sixty‐three dogs with CVHD.

Methods

Prospective, multicenter, cross‐sectional study. Each dog underwent physical examination, echocardiography, thoracic radiography, and LUS. The LUS findings were classified as absent, rare, numerous, or confluent B‐lines. Sensitivity, specificity, and positive and negative predictive values of LUS B‐lines to identify PE were calculated using thoracic radiography as the reference standard.

Results

Dogs in stage B1 had absent or rare B‐lines in 14 of 15 cases (93.3%). Dogs in stage B2 had absent or rare B‐lines in 16 of 18 cases (88.9%). All dogs in stage C, without radiographic signs of PE, had absent or rare B‐lines. Dogs in stage C, with radiographic signs of PE, had numerous or confluent B‐lines in 18 of 20 cases (90%). Lung ultrasound examination detected PE with a sensitivity of 90%, specificity of 93%, and with positive and negative predictive values of 85.7 and 95.2%, respectively.

Conclusions and Clinical Importance

Lung ultrasound examination showed good diagnostic accuracy to identify cardiogenic PE and might be helpful in staging dogs with CVHD. Lung ultrasound examination should be considered as a new, noninvasive diagnostic tool for clinicians managing CVHD in dogs.

Long-term effect of sildenafil on echocardiographic parameters in dogs with asymptomatic myxomatous mitral valve degeneration

Sildenafil is a selective phosphodiesterase-5 inhibitor that has been demonstrated to delay ventricular remodeling in humans and experimental animals. The aim of this prospective study was to assess the chronic effects of sildenafil administration on echocardiographic indices and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in dogs with naturally occurring, asymptomatic myxomatous mitral valve degeneration. Thirty client-owned dogs with ACVIM class B1 or B2 were enrolled. Dogs were randomly assigned to treatment (sildenafil 1–3 mg/kg, PO, BID for 180 days) or control groups. A total of 12 dogs completed the 180 days trial in the sildenafil group, whereas 10 dogs remained in control group. When comparing the difference from baseline values obtained over time between groups, the stroke volume (SV) at day 30 was significantly higher in the sildenafil group (P=0.038). The LA/Ao and the MR jet area were significantly lower beginning at day 30 (only MR jet area; P=0.006), day 90 (P=0.006 and P=0.027, respectively) and day 180 (P=0.029 and P=0.032, respectively). The 2D-LA was significantly lower at day 90 when compared with control group (P=0.028). The differences of NTproBNP from baseline were significantly lower when compared with control group at the same timepoint (D90, P=0.017 and D180, P=0.013). In conclusion, this study suggested that long-term treatment with sildenafil prevented aggravation of disease progression as suggested by several echocardiographic indices (i.e. SV, LA/Ao, MR jet area, 2D-LA) and reduced NTproBNP level at the indicated timepoints in dogs with asymptomatic mitral valve degeneration.

Intravenous administration of puppy deciduous teeth stem cells in degenerative valve disease

Aim:

The objective of this study is to investigate the improvement of heart function in dogs with chronic valvular heart disease after puppy deciduous teeth stem cells (pDSCs) administration.

Materials and Methods:

20 client-owned dogs with degenerative valvular heart disease underwent multiple intravenous injections of allogeneic pDSCs. Dogs were randomly assigned to two groups: (i) Control group (n=10) with standard treatment for heart failure and (ii) group with standard treatment and multiple administrations of pDSCs (n=10). Electrocardiography, complete transthoracic echocardiography, thoracic radiography, and blood pressure were recorded before and after pDSCs injections for 15, 30 and 60 days.

Results:

Post pDSCs injection showed measurable improvement in left ventricular ejection fraction, American College of Veterinary Internal Medicine (ACVIM) functional class significantly improved and improved quality of life scores were observed. In the control group, there were no significant enhancements in heart function or ACVIM class.

Conclusions:

This finding suggests that pDSCs could be a supplement for valvular heart disease treatment.

Cloning and Sequencing of Equine Cardiac Troponin I and Confirmation of Its Usefulness as a Target Analyte for Commercial Troponin I Analyzers

The analysis of cardiac troponin I (cTnI) in the diagnosis of myocardial injury in domestic animals is gaining popularity. In this study, equine cTnI was sequenced and compared with previously characterized cTnI from other species. A 6-amino-acid N-terminal deletion unique to the horse was identified. This deletion was outside the epitope region of cTnI recognized by most commercial immunoassays and did not affect the ability of a commercial analyzer system to detect recombinant equine cTnI. No function could be ascribed to the deleted portion. These data support the use of commercial analyzers in measuring equine cTnI.

Plasma atrial natriuretic peptide and N-terminal pro B-type natriuretic peptide concentrations in dogs with right-sided congestive heart failure

The clinical utility of plasma natriuretic peptide concentrations in dogs with right-sided congestive heart failure (CHF) remains unclear. We investigated whether plasma levels of atrial natriuretic peptide (ANP) and N-terminal pro B-type natriuretic peptide (NT-proBNP) are useful for assessing the congestive signs of right-sided heart failure in dogs. This retrospective study enrolled 16 healthy dogs and 51 untreated dogs with presence (n=28) or absence (n=23) of right-sided CHF. Medical records of physical examinations, thoracic radiography and echocardiography were reviewed. The plasma concentration of canine ANP was measured with a chemiluminescent enzyme immunoassay. Plasma NT-proBNP concentrations were determined using an enzyme immunoassay. Plasma ANP and NT-proBNP concentrations in dogs with right-sided CHF were significantly higher than in healthy controls and those without right-sided CHF. The plasma NT-proBNP concentration >3,003 pmol/l used to identify right-sided CHF had a sensitivity of 88.5% and specificity of 90.3%. An area under the ROC curve (AUC) was 0.93. The AUC for NT-proBNP was significantly higher than the AUCs for the cardiothoracic ratio, vertebral heart score, ratio of right ventricular end-diastolic internal diameter to body surface area, tricuspid late diastolic flow and ratio of the velocities of tricuspid early to late diastolic flow. These results suggest that plasma ANP and NT-proBNP concentrations increase markedly in dogs with right-sided CHF. Particularly, NT-proBNP is simple and helpful biomarkers to assess the right-sided CHF.

Pulmonary Vein-to-Pulmonary Artery Ratio is an Echocardiographic Index of Congestive Heart Failure in Dogs with Degenerative Mitral Valve Disease

BACKGROUND

Early recognition of left-sided congestive heart failure (CHF) in dogs with degenerative mitral valve disease (DMVD) is important because it influences medical therapy, timing of follow-up, and outcome.

HYPOTHESIS

Pulmonary vein diameter-to-pulmonary artery diameter ratio (PV/PA) measured by echocardiography can predict CHF.

ANIMALS

Ninety-eight client-owned dogs, 37 controls, and 61 dogs with DMVD.

METHODS

Prospective clinical cohort study. History, physical examination and Doppler-echocardiography were performed. Dogs were classified as International Small Animal Cardiac Health Council class I, II or III. Congestive heart failure was identified in a subset of 56 dogs based on radiographic findings. The PV/PA was measured in bidimensional (2D) and M-mode by 2 investigators blinded to the radiologists' conclusions.

RESULTS

Interobserver coefficients of variation for PV/PA acquisition and measurement were <10%. The PV/PA in control dogs was approximately 1 and increased with class of heart failure. The presence of CHF could be best predicted by measuring PV/PA in 2D echocardiography (cut-off, 1.7; area under the curve, 0.98; CI, 0.97-0.98; P < .001) with a sensitivity of 96% and a specificity of 91%.

CONCLUSION AND CLINICAL IMPORTANCE

The PV/PA is a simple and reproducible echocardiographic variable that increases with class of heart failure and may help discriminate dogs in CHF from asymptomatic dogs with DMVD. Additional studies are required to determine whether PV/PA might provide additional information in the integrated interpretation of Doppler-echocardiographic indices of left ventricular filling pressures and could be used for rapid assessment of CHF in dogs in a critical care setting.

Circulating natriuretic peptide concentrations in hyperthyroid cats

OBJECTIVES

To assess the influence of thyroid function on natriuretic peptide concentration in hyperthyroid cats before and after treatment.

METHODS

Serum natriuretic peptide concentration was measured in 61 hyperthyroid cats recruited from first-opinion clinics before and after treatment.

RESULTS

Following successful treatment, total thyroxine, heart rate, systolic blood pressure and packed cell volume all decreased and bodyweight and creatinine concentrations increased. Furthermore, a significant (P < 0·001) decline in NT-proBNP concentration but not NT-proANP was identified.

CLINICAL SIGNIFICANCE

Thyroid function has a modest but significant effect on NT-proBNP concentration. Thyroid status should be taken into account when interpreting NT-proBNP concentrations in cats.

Lowered N-terminal pro-B-type natriuretic peptide levels in response to treatment predict survival in dogs with symptomatic mitral valve disease

OBJECTIVES

In humans with congestive heart failure (CHF), better outcome is correlated with lower natriuretic peptide (NP) levels after starting treatment and greater percentage reduction of NP levels. Therefore, the aim of this study was to determine the relationship between absolute and relative changes in N-terminal pro-B-type natriuretic peptide (NT-proBNP) and pro-atrial natriuretic peptide 31-67 (proANP 31-67) and overall cardiac survival in patients with symptomatic myxomatous mitral valve disease (MMVD). Furthermore, we sought to compare clinical and echocardiographic status of 12-month survivors and non-survivors.

ANIMALS, MATERIALS AND METHODS

26 dogs with CHF due to MMVD. Initial NP levels, as well as absolute and percentage changes of follow-up NP levels (between 7 and 30 days after treatment start) and heart failure (HF) class were tested as potential predictors of overall cardiac survivorship. Additionally, various echocardiographic parameters, creatinine concentrations and furosemide doses were compared between 12-month survivors and non-survivors.

RESULTS

Dogs with follow-up NT-proBNP level <965 pmol/l had a significantly longer overall cardiac survival than patients with NT-proBNP level >965 pmol/l (P = 0.03). Dogs in a higher HF class had a significantly (P = 0.03) higher probability of shorter survival independent of their NP levels. When dogs were grouped by 12-month survival, only follow-up NT-proBNP levels were significantly different between groups.

CONCLUSIONS

HF class at presentation and NT-proBNP levels after initiating treatment are predictive of mortality in patients with symptomatic MMVD. ProANP 31-67 levels, percentage reduction in NPs levels, creatinine or urea concentration, echocardiographic parameters and furosemide dose did not predict outcome.

Methods for the development and assessment of atrial fibrillation and heart failure dog models

Objective

To report Medtronic experiences with the development of animal models for atrial fibrillation (AF) and chronic heart failure (CHF) using high-rate pacing for AF and microemboli for CHF.

Methods

For the AF model, an atrial lead was attached to a Medtronic Synergy™ neurostimulator, which was programmed to stimulate at 50 Hz in an on-off duty cycle. Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and N-terminal pro brain natriuretic peptide (NT-proBNP) were assayed at select time points. For CHF model, a serial injection of 90 µm polystyrene microspheres at 62,400 beads/mL (Polybead, Polysciences, Inc.) was performed to induce global ischemia, either with weekly monitoring and embolization schedule (group 1, n = 25) or with biweekly monitoring and emboliation schedule (group 2, n = 36 ). Echocardiograms were used along with ventriculograms and magnetic resonance imaging scans weekly to assess cardiac function and ANP, BNP and NT-proBNP were monitored.

Results

For the AF model, the days to sustained AF for four animals following surgery were 7, 25, 21 and 19, respectively; For the CHF model, the days to meet CHF endpoints were 116 in group 1 and 89 in group 2. For both AF and CHF models, NT-proBNP correlated well with the development of disease states.

Conclusion

Our experience for the development and assessment of AF and CHF dog models may help researchers who are in search for animal model for assessing the safety and efficacy of a device-based therapy.

Resting and dobutamine stress test induced serum concentrations of brain natriuretic peptide in German Shepherd dogs

Studies of clinical uses of brain natriuretic peptide (BNP) represent one of the most important advances in cardiology since the introduction of echocardiography as a clinical diagnostic procedure. Defining the clinical potential of BNP in canine cardiology has not been completed yet. The aim of this study is to measure BNP concentrations in healthy German Shepherd dogs of different ages as a baseline in resting and when conventional protocol of the dobutamine stress test (DST) is applied to dogs. Concentrations of BNP were measured in blood serum by the radioimmunoassay method. The values of BNP concentrations were compared to cardiac parameters obtained by standard cardiac diagnostic procedures (radiology, electrocardiography and echocardiography). No significant differences in serum BNP concentrations existed in dogs of different ages. A statistically significant increase in BNP concentrations was registered after DST. These changes in BNP concentrations were related to ST/T electrocardiographic changes, and correlated to changes in the left ventricular internal diameter in systole (LVESD). These data suggest that BNP is not increased in aged dogs with normal cardiac systolic function and renal function, and that myocardial ischemia leads to a significant increase in BNP concentrations even in dogs with normal left ventricular function.

Prediction of first onset of congestive heart failure in dogs with degenerative mitral valve disease: the PREDICT cohort study

OBJECTIVE

To identify risk factors for first-onset congestive heart failure (CHF) in dogs with degenerative mitral valve disease (DMVD).

ANIMALS

Eighty-two dogs with and without CHF secondary to DMVD were retrospectively assigned to a derivation cohort. Sixty-five dogs with asymptomatic DMVD were recruited into a prospective validation cohort.

METHODS

Variables associated with risk of CHF in dogs were identified in a derivation cohort and used to construct a predictive model, which was then prospectively tested through longitudinal examination of a validation cohort.

RESULTS

Logistic regression analysis of the derivation cohort yielded a predictive model that included the left atrial to aortic root dimension ratio (LA:Ao) and plasma concentration of N-terminal pro-B-type natriuretic peptide (NT-proBNP). When this model was prospectively applied to the validation cohort, it correctly predicted first-onset of CHF in 69.2% of cases. Analysis of the validation cohort revealed that plasma NT-proBNP concentration and indexed left ventricular end-diastolic diameter (LVIDd:Ao) were independent risk factors for development of first-onset CHF in dogs with DMVD (NT-proBNP ≥ 1500 pmol/L, odds ratio (OR), 5.76, 95% confidence interval (CI), 1.37-24.28, P = 0.017; LVIDd:Ao ≥ 3, OR, 6.11, 95% CI, 1.09-34.05, P = 0.039).

CONCLUSIONS

Measures of left heart size and plasma NT-proBNP concentration independently estimate risk of first-onset of CHF in dogs with DMVD. These parameters can contribute to the management of dogs with DMVD.

Sleeping respiratory rates in apparently healthy adult dogs

Respiratory rate monitoring of cardiac patients is recommended by many cardiologists. However, little objective data exist about respiratory rates in apparently healthy dogs when collected in the home environment. We measured sleeping respiratory rates (SRR) in apparently healthy dogs and compared sleeping and resting respiratory rates (RRR) with a cross-sectional prospective study. Participants collected 12-14 one-minute SRR over a period ranging from 1 week to 2 months on 114 privately owned adult dogs. Selected participants simultaneously collected RRR. Mean within-dog average SRR (SRR(mean)) was 13breaths per minute (breaths/min). No dog had SRR(mean) >23 breaths/min; three dogs had instantaneous SRR measurements >30 breaths/min. Dogs had higher RRR(mean) (19 breaths/min) than SRR(mean) (15 breaths/min) (P<0.05). Canine SRR(mean) was unaffected by age, bodyweight or geographic location. Data acquisition was considered relatively simple by most participants. This study shows that apparently healthy adult dogs generally have SRR(mean) <30 breaths/min and rarely exceed this rate at any time.

Detection of congestive heart failure in dogs by Doppler echocardiography

BACKGROUND

Echocardiographic prediction of congestive heart failure (CHF) in dogs has not been prospectively evaluated.

HYPOTHESIS

CHF can be predicted by Doppler echocardiographic (DE) variables of left ventricular (LV) filling in dogs with degenerative mitral valve disease (MVD) and dilated cardiomyopathy (DCM).

ANIMALS

Sixty-three client-owned dogs.

METHODS

Prospective clinical cohort study. Physical examination, thoracic radiography, analysis of natriuretic peptides, and transthoracic echocardiography were performed. Diagnosis of CHF was based upon clinical and radiographic findings. Presence or absence of CHF was predicted using receiver-operating characteristic (ROC) curve, multivariate logistic and stepwise regression, and best subsets analyses.

RESULTS

Presence of CHF secondary to MVD or DCM could best be predicted by E:isovolumic relaxation time (IVRT) (area under the ROC curve [AUC]=0.97, P<.001), respiration rate (AUC=0.94, P<.001), Diastolic Functional Class (AUC=0.93, P<.001), and a combination of Diastolic Functional Class, IVRT, and respiration rate (R2=0.80, P<.001) or Diastolic Functional Class (AUC=1.00, P<.001), respiration rate (AUC=1.00, P<.001), and E:IVRT (AUC=0.99, P<.001), and a combination of Diastolic Functional Class and E:IVRT (R2=0.94, P<.001), respectively, whereas other variables including N-terminal pro-brain natriuretic peptide, E:Ea, and E:Vp were less useful.

CONCLUSION AND CLINICAL IMPORTANCE

Various DE variables can be used to predict CHF in dogs with MVD and DCM. Determination of the clinical benefit of such variables in initiating, modulating, and assessing success of treatments for CHF needs further study.

Therapeutic changes of plasma N-terminal pro-brain natriuretic peptide concentrations in 9 dogs with patent ductus arteriosus

The plasma N-terminal proBNP (NT-proBNP) concentration is measured for determining the diagnosis and severity of heart failure in dogs. However, it is still unclear whether measurements of circulating NT-proBNP levels provide clinical utility as an indicator of therapeutic efficacy. Thus, we investigated the surgical correction-related changes of plasma NT-proBNP concentrations in 9 dogs with patent ductus arteriosus (PDA). Physical examination, thoracic radiography and echocardiography were conducted both before and after surgery. Similarly, the plasma NT-proBNP concentrations were determined using an enzyme immunoassay for canine pro-BNP. The International Small Animal Cardiac Health Council (ISACHC) class and murmur grade were significantly improved after surgery compared with before surgery. Vertebral heart size (VHS) and cardiothoracic ratio (CTR) were significantly decreased after surgery. Fractional shortening was significantly decreased and relative wall thickness (RWT) was significantly increased after surgery. Furthermore, the plasma NT-proBNP concentrations were significantly decreased by surgical correction. The plasma NT-proBNP concentration showed significant positive correlation with the ISACHC class, murmur grade, VHS and CTR and significant negative correlation with the RWT. Therefore, measurement of plasma NT-proBNP levels can be used to monitor the effectiveness of therapies such as surgical correction of PDA.

Assessment of serum N-terminal pro-B-type natriuretic peptide concentration for differentiation of congestive heart failure from primary respiratory tract disease as the cause of respiratory signs in dogs

OBJECTIVE

To determine whether serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration is useful in discriminating between cardiac and noncardiac (ie, primary respiratory tract disease) causes of respiratory signs (ie, coughing, stertor, stridor, excessive panting, increased respiratory effort, tachypnea, or overt respiratory distress) in dogs.

DESIGN

Multicenter cross-sectional study.

ANIMALS

P 115 dogs with respiratory signs.

PROCEDURES

Dogs with respiratory signs were solicited for study. Physical examination, thoracic radiography, and echocardiography were used to determine whether respiratory signs were the result of cardiac (ie, congestive heart failure) or noncardiac (ie, primary respiratory tract disease) causes. Serum samples for NT-proBNP assay were obtained at time of admission for each dog. Receiver-operating characteristic curves were constructed to determine the ability of serum NT-proBNP concentration to discriminate between cardiac and noncardiac causes of respiratory signs.

RESULTS

Serum NT-proBNP concentration was significantly higher in dogs with cardiac versus noncardiac causes of respiratory signs. In dogs with primary respiratory tract disease, serum NT-proBNP concentration was significantly higher in those with concurrent pulmonary hypertension than in those without. A serum NT-proBNP cutoff concentration > 1,158 pmol/L discriminated between dogs with congestive heart failure and dogs with primary respiratory tract disease with a sensitivity of 85.5% and a specificity of 81.3%.

CONCLUSIONS AND CLINICAL RELEVANCE

Measuring serum NT-proBNP concentration in dogs with respiratory signs helps to differentiate between congestive heart failure and primary respiratory tract disease as an underlying cause.

N-terminal pro B-type natriuretic peptide and left ventricular diameter independently predict mortality in dogs with mitral valve disease

OBJECTIVES

To determine whether natriuretic peptide concentrations would predict all cause mortality in dogs with degenerative mitral valve disease.

METHODS

One hundred dogs with naturally occurring degenerative mitral valve disease were prospectively recruited for this longitudinal study. Analysis of outcome was undertaken for 73 dogs for which the outcome was known. Dogs underwent physical examination, electrocardiography and echocardiography. Natriuretic peptide concentrations were measured by Enzyme-linked immunosorbent assay. The ability of natriuretic peptide concentrations, clinical, electrocardiographic and echocardiographic data, to predict all cause mortality was determined using univariable and multivariable Cox proportional hazards analyses.

RESULTS

Thirty dogs died during the period of follow-up. Two variables were independently predictive of all cause mortality; these were the normalised left ventricular end-diastolic diameter and the N-terminal pro B-type natriuretic peptide concentration. An increase of the left ventricular end-diastolic diameter by 0.1 increased the hazard of all cause mortality by 20% (95% confidence interval: 4 to 37%, P=0.01) and a 100 pmol/l increase in N-terminal pro B-type natriuretic peptide increased the hazard by 7% (95 confidence interval: 2 to 11%, P=0.003).

CLINICAL SIGNIFICANCE

N-terminal pro B-type natriuretic peptide concentration and left ventricular end-diastolic diameter are significantly and independently predictive of all cause mortality in dogs with degenerative mitral valve disease.

Reader performance in radiographic diagnosis of signs of mitral regurgitation in cavalier King Charles spaniels

OBJECTIVES

To measure accuracy and variability of diagnosis by radiography of heart enlargement (HE) and heart failure (HF) in mitral regurgitation (MR).

METHODS

Sixteen readers representing four levels of experience evaluated 50 sets of radiographs with varying severity of MR for presence or absence of HE, left atrial enlargement (LAE) and HF. The performance of the readers was compared with a reference standard, using area under the curve (AUC) of receiver operating characteristic (ROC) curves. The interreader agreement value kappa (K) was calculated. A subset of difficult cases of HF was analysed before and after removing an outlying reader from each group.

RESULTS

AUC for HE was 0.89, for LAE it was 0.93 and for HF it was 0.92. Experience increased certainty of diagnosis but not accuracy. K ranges were HE, 0.53 to 0.67; LAE, 0.61 to 0.69 and HF, 0.49 to 0.58. When only difficult cases of HF were read, accuracy decreased and experienced readers performed better than inexperienced. When outlying readers were excluded, the differences between experienced and inexperienced readers increased.

CLINICAL SIGNIFICANCE

LAE, not HE, should be used to evaluate the heart size and indirectly the severity of MR on radiographs. For HF, agreement among individual readers was only moderate. Studies of reader accuracy should consider the effects of interreader variability.

Assessment of the diagnostic accuracy of circulating natriuretic peptide concentrations to distinguish between cats with cardiac and non-cardiac causes of respiratory distress

OBJECTIVES

To determine if serum natriuretic peptide (NP) concentrations could distinguish cardiac from non-cardiac causes of respiratory distress (RD) in cats.

ANIMALS

Seventy-four cats from 1 university hospital were used.

METHODS

Serum NP concentrations were measured in 41 cats with non-cardiac respiratory distress (RD-NC) and compared to 33 cats with RD due to congestive heart failure (RD+CHF) using sandwich enzyme immunoassays (ELISA).

RESULTS

RD-NC cats had lower (P=0.0001) median NT-proANP and NT-proBNP concentrations (614 and 45 fmol/mL, respectively) than RD+CHF cats (1690 and 523 fmol/mL, respectively). The area under the curve was 0.88 and 0.96 for the receiver operating curve analysis of the diagnostic accuracy of NT-proANP and NT-proBNP concentrations to discriminate RD+CHF from RD-NC cats (P=0.036). An optimum cut-off concentration of 986 fmol/mL for NT-proANP and 220 fmol/mL for NT-proBNP accurately discriminated RD-NC from RC+CHF cats with a sensitivity of 93.8% and 93.9% and a specificity of 80.3% and 87.8%, respectively.

CONCLUSIONS

Serum NP concentrations were different in RD+CHF cats compared to RD-NC cats. Evaluation of circulating NP concentrations may be helpful in the initial approach to cats presenting with respiratory distress, particularly if advances in ELISA technology result in a rapid cage-side test.

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.

The diagnostic accuracy of different natriuretic peptides in the investigation of canine cardiac disease

OBJECTIVES

We aimed to validate and determine the accuracy of a new sandwich ELISA for canine N-terminal pro-B-type natriuretic peptide (NT-proBNP) in the discrimination of canine patients with cardiac disease from those with respiratory disease and to determine the effect of confounding variables on NT-proBNP concentrations.

METHODS

Validation studies for the new assay were undertaken. Concentrations of N-terminal atrial natriuretic peptide (NT-proANP) and NT-proBNP in both ethylenediaminetetraacetic acid (EDTA) plasma and serum were estimated in samples from 77 dogs at a laboratory blinded to the clinical status of the patient. The diagnostic accuracy of the each sample type and test was evaluated using receiver operating characteristic curves. The effect of age, gender and indicators of renal function was evaluated using a multivariate regression analysis.

RESULTS

Concentrations of NT-proBNP in both serum and plasma accurately discriminated dogs with respiratory disease from those with cardiac disease, with an optimum cut-off concentration of 210 pmol/l. NT-proBNP concentrations were unaffected by sample type. Increasing creatinine concentration is associated with increasing concentration of NT-proBNP. Age and gender were not found to have significant effects on natriuretic peptide concentrations in this population.

CLINICAL SIGNIFICANCE

Canine NT-proBNP appears to be a useful marker of the presence of cardiac disease, although concentrations must be interpreted in the light of the patient's renal function.

Analytical validation of commercial immunoassays for the measurement of cardiovascular peptides in the dog

Immunoassays for the measurement of concentrations of the cardiovascular peptides pro-atrial natriuretic peptide (proANP), brain natriuretic peptide (BNPPen and BNPPhoe), endothelin-1 (ET-1Bio, ET-1IBL and ET-1Phoe) and big endothelin-1 (Big-ETBio and Big-ETIBL) were validated in canine serum by determination of intra-assay variability and dilutional parallelism. Commercial kits that showed good results were further validated by determination of intra- and inter-assay variability, dilutional parallelism and spiking recovery. Assays for proANP, BNPPhoe, ET-1IBL and Big-ETIBL showed acceptable results in the preliminary validation and were fully validated. The intra- and inter-assay variability was acceptable for all four assays, linearity was demonstrated and recovery rates were acceptable. The performances of the different immunoassays varied considerably, underscoring the importance of validation. Of the assays studied, proANP, BNP(Phoe), ET-1IBL and Big-ETIBL produced precise, reproducible and accurate results and can be recommended for clinical application.

Evaluation of serum cardiac troponin I concentration in Boxers with arrhythmogenic right ventricular cardiomyopathy

OBJECTIVE

To evaluate serum cardiac troponin I (cTnI) concentrations in Boxers with arrhythmogenic right ventricular cardiomyopathy (ARVC), unaffected (control) Boxers, and control non-Boxers.

ANIMALS

10 Boxers with a clinical diagnosis of ARVC defined by > or = 1,000 ventricular premature complexes (VPCs)/24 h on an ambulatory ECG, 10 control Boxers assessed as normal by the presence of < 5 VPCs/24h, and 10 control non-Boxers.

PROCEDURES

Serum was extracted from a blood sample from each dog. Analysis of serum cTnI concentrations was performed.

RESULTS

Mean +/- SD serum cTnI concentration was 0.142 +/- 0.05 ng/mL for Boxers with ARVC, 0.079 +/- 0.03 ng/mL for control Boxers, and 0.023 +/- 0.01 ng/mL for control non-Boxers. A significant difference in serum cTnI concentrations was observed among the 3 groups. In the combined Boxer population (ie, Boxers with ARVC and control Boxers), a significant correlation was found between serum cTnI concentration and number of VPCs/24 h (r = 0.78) and between serum cTnI concentration and grade of ventricular arrhythmia (r = 0.77).

CONCLUSIONS AND CLINICAL RELEVANCE

Compared with clinically normal dogs, Boxers with ARVC had a significant increase in serum cTnI concentration. For Boxers, correlations were found between serum cTnI concentration and number of VPCs/24 h and between concentration and the grade of arrhythmia. Because of the overlap in serum cTnI concentrations in control Boxers and Boxers with ARVC, future studies should evaluate the correlation of serum cTnI concentration with severity of disease in terms of degree of myocardial fibrofatty changes.

Canine nonischemic left ventricular dysfunction: a model of chronic human cardiomyopathy

BACKGROUND

The mechanisms of cardiac remodeling during chronic heart failure remain poorly defined. We sought to advance a chronic canine model of nonischemic cardiomyopathy.

METHODS AND RESULTS

Male dogs (n = 6) received decremental right ventricular apical tachypacing (12 months) to achieve and maintain stable left ventricular (LV) dysfunction. After 10 months of tachypacing, 120 beats/min was sufficient to maintain stable LV dysfunction. Electrocardiography, echocardiography, and tissue Doppler imaging were done to evaluate electrophysiology, LV dimensions and function, and dyssynchrony during normal sinus rhythm. The 6-minute walk test was used to evaluate functional capacity. We observed increases in both QRS duration (P < .0001) and QRS amplitude (P < .0001). LV fractional shortening was reduced from a baseline of 38.0 +/- 1.4% to 11.2 +/- 1.4% (P < .0001). LV end-diastolic dimension increased from 3.8 +/- 0.1 cm at baseline to 5.3 +/- 0.3 cm (P < .0001); LV end-systolic dimension increased from 2.3 +/- 0.1 cm to 4.7 +/- 0.2 cm (P < .0001). LV mass increased from 85.9 +/- 3.5 g at baseline to 179 +/- 13.7 g (P < .0001). There was evidence of LV dyssynchrony (P < .04) during both normal sinus rhythm and right ventricular tachypacing, compared with control dogs. The distance a dog walked in 6 minutes was significantly less at 12 months compared with normal controls (540 +/- 32 m versus 277 +/- 64 m, P < .008).

CONCLUSION

This nonischemic model of canine cardiomyopathy reproduces many aspects of chronic human heart failure including reduced fractional shortening, dilated ventricular dimensions, increased LV mass, decreased functional capacity, and dyssynchrony.

Cardiac troponin I: evaluation of a biomarker for the diagnosis of heart disease in the dog

OBJECTIVES

To assess the value of measuring blood levels of the myocardial protein cardiac troponin I (cTnl) in the diagnosis of congenital and acquired heart disease in the dog and in the evaluation of the severity of heart failure.

METHODS

Serum samples obtained from healthy dogs (n = 26) and from dogs diagnosed with a variety of congenital and acquired heart conditions (n = 35) were assayed for cTnl concentration using an automated immunoassay method. Results were also analysed according to the degree of heart failure as assessed using the International Small Animal Cardiac Health Council's scheme.

RESULTS

Healthy dogs had very low or undetectable blood cTnl levels, as did dogs with congenital heart disease. However, cTnl levels were significantly elevated in dogs with acquired mitral valve disease, dilated cardiomyopathy and pericardial effusion. Blood cTnl levels also varied with severity of heart failure.

CLINICAL SIGNIFICANCE

Measurement of blood cTnl levels may be a useful aid in the diagnosis of dogs with suspected heart disease and in indicating the severity of heart failure.