The diagnostic relevance of NT-proBNP and proANP 31-67 measurements in staging of myxomatous mitral valve disease in dogs

Differentially expressed platelet activation-related genes in dogs with stage B2 myxomatous mitral valve disease

BACKGROUND

Peripheral blood carries a reservoir of mRNAs that regulate cardiac structure and function potential. Although it is well recognized that the typical symptoms of Myxomatous Mitral Valve Disease (MMVD) stage B2 are long-standing hemodynamic disorder and cardiac structure remodeling caused by mitral regurgitation, the transcriptomic alterations in blood from such dogs are not understood.

RESULTS

In the present study, comparative high-throughput transcriptomic profiling of blood was performed from normal control (NC) and naturally-occurring MMVD stage B2 (MMVD) dogs. Using Weighted Gene Co-expression Network Analyses (WGCNA), Gene Ontology (GO), and Kyoto Encyclopedia of Gene and Genomes (KEGG), we identified that the turquoise module was the most highly correlated with echocardiographic features and found 64 differentially expressed genes (DEGs) that were significantly enriched in platelet activation related pathways. Therefore, from the turquoise module, we selected five DEGs (MDM2, ROCK1, RIPK1, SNAP23, and ARHGAP35) that, according to real-time qPCR, exhibited significant enrichment in platelet activation related pathways for validation. The results showed that the blood transcriptional abundance of MDM2, ROCK1, RIPK1, and SNAP23 differed significantly (P < 0.01) between NC and MMVD dogs. On the other hand, Correlation Analysis revealed that MDM2, ROCK1, RIPK1, and SNAP23 genes negatively regulated the heart structure parameters, and followed the same trend as observed in WGCNA.

CONCLUSION

We screened four platelet activation related genes, MDM2, ROCK1, RIPK1, and SNAP23, which may be considered as the candidate biomarkers for the diagnosis of MMVD stage B2. These findings provided new insights into MMVD pathogenesis.

Aldosterone-progesterone relationship in sexually intact Chihuahua bitches

BACKGROUND

Aldosterone represents an important target of heart failure therapy and may be a valuable indicator of the renin-angiotensin-aldosterone system activity. However, its assessment might be challenging because of the effect of individual factors. In a recent study, intact female dogs showed the highest value of urinary aldosterone-to-creatinine ratio (UAldo:C) compared to other sex categories. In humans and rodents, an influence of progesterone has been reported by several studies. To our knowledge, the relationship between aldosterone and progesterone has not yet been investigated in dogs. The aim of this prospective study was to investigate this relationship in sexually intact Chihuahua females, measuring both hormones twice in the same bitch, that is in anoestrus when progesterone concentrations are baseline and in dioestrus when they are high.

RESULTS

The study population consisted of 14 sexually intact Chihuahua bitches. Serum progesterone (34.06 (21.17-44.90) vs. 0.19 [0.13-0.38] ng/ml; P < 0.001) and urinary aldosterone (9886.98 ± 5735.22 vs. 5005.72 ± 2127.73 pg/ml; P = 0.01) were significantly higher in dioestrus compared to anoestrous. Urinary aldosterone-to-creatinine ratio was higher in dioestrus compared to anoestrus (4.16 [3.17-6.80] vs. 3.39 ± 1.64 µg/g), but it did not reach the statistical significance (P = 0.056). Serum progesterone showed a moderate positive correlation with urinary aldosterone (ρ = 0.638, P < 0.001) and UAldo:C (ρ = 0.516, P = 0.005).

CONCLUSIONS

The results of the present study suggest the existence of a progesterone-aldosterone relationship in canine species, indicating that sex and phase of reproductive cycle should be taken into account when interpreting aldosterone concentrations. Further studies are needed to confirm these results on a larger canine population and to identify the underlying mechanisms in this species.

Association of Paraoxonase-1 and NT-proBNP with Clinical, Clinico-Pathologic and Echocardiographic Variables in Dogs with Mitral Valve Disease

The objective of the present study was to measure the concentration of Paraoxonase-1 (PON-1) and N-terminal-prohormone-B-type natriuretic peptide (NT-proBNP), in the serum of dogs with degenerative Mitral Valve Disease (MVD), in order to identify their association with the clinical stage and specific clinico-pathologic and echocardiographic findings.Eighty dogs diagnosed with MVD and staged according to the ACVIM (American College of Veterinary Internal Medicine) consensus statement (B1, B2, C and D), based on their clinical, radiographic, and echocardiographic findings, were included in the study. NT-proBNP was measured only in stage B1 and B2 dogs. Clinical stage did not have a significant effect on PON-1 concentrations (p = 0.149), but NT-proBNP levels were lower in B1 dogs (p = 0.001). A significant correlation between PON-1 and total plasma proteins (p = 0.001), albumin (p = 0.003) and white blood cell count (p = 0.041) was detected, whereas there was no significant correlation (p = 0.847) between PON-1 and NT-proBNP concentrations. PON-1 showed a significant but weak negative correlation with normalized left ventricular internal diameter at diastole (LVIDdn) (p = 0.022) and systole (LVIDsn) (p = 0.012), as well as mitral valve E to A wave velocity ratio (MV E/A) (p = 0.015), but not with Left Atrial to Aortic root ratio (LA/Ao) (p = 0.892) or fractional shortening (FS%) (p = 0.944). PON-1 seems to be an insensitive marker of clinical stage and disease severity in MVD, but can be indicative of some clinico-pathological and echocardiographic changes. NT-proBNP changes are independent of oxidative stress.

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.

The effect of myxomatous mitral valve disease severity on packed cell volume in dogs

OBJECTIVES

The aim of this study was to examine whether associations between disease severity and packed cell volume exist in dogs with myxomatous mitral valve disease.

MATERIALS AND METHODS

Data were selected from 289 dogs that had been examined at a research clinic (2004-2017) on multiple occasions (n=1465). American College of Veterinary Internal Medicine stage and echocardiographic measurements were entered in separate multivariable linear mixed effects models with packed cell volume as the dependent variable. Age, breed, sex, weight and blood urea nitrogen concentrations were additionally tested in these analyses to control for patient characteristics.

RESULTS

Packed cell volume (% whole blood) in stages B1 and B2 (B1: 42.62 ±0.27, P=0.001; B2: 41.77± 0.42, P < 0.001) was lower than stage A (44.57 ±0.53). In stage C, packed cell volume was greater than both preclinical stages (C: 43.84 ±0.46). When the administration of loop diuretics was included in statistical models, packed cell volume was inversely related to normalised left ventricular internal diameters (β: -2.37; 95% confidence intervals: -3.49, -1.25; P < 0.001).

CLINICAL SIGNIFICANCE

Dogs with myxomatous mitral valve disease may develop reductions in packed cell volume as their disease progresses. Although this finding was statistically significant at a population level, it should be noted that the differences described are relatively small. This, along with other causes of variation in packed cell volume, means that changes would be challenging to appreciate within individual patients. Plasma volume depletion following diuretic administration may explain why findings differed in stage C.

Serum proteome profiling in canine chronic valve disease using a TMT-based quantitative proteomics approach

Chronic valve disease (CVD) is the most common clinically significant heart disease of dogs, affecting 20 to 40% of dogs. The aim of this study was to evaluate the serum protein profile of healthy and CVD affected dogs, by means of an isobaric tandem mass tag (TMT) label-based high-resolution quantitative proteomic approach. Additionally, conventional cardiac biomarkers were measured in the serum, functional bioinformatics analysis was employed for elucidating molecular mechanisms and pathways associated with CVD, and validation of proteomic results was performed by immunoassays and Western blotting. Of 290 identified and quantified proteins, 15 proteins showed significantly different abundances (p < .05), including antithrombin-III, alpha-2-antiplasmin, tetranectin, apolipoprotein M, adiponectin, inter-alpha-trypsin inhibitor heavy chain H1, gelsolin and apolipoprotein B-100. The identified proteins with differently abundances are involved in a number of pathways, such as complement and coagulation cascades, haemostasis, regulation of actin cytoskeleton, lipid metabolism and transport. We found comparative similarities with human disease in terms of identified proteins and GO pathways, which confirmed similar pathophysiology of this disease, but also differences, mainly in lipid metabolism. SIGNIFICANCE: There have been few investigations of canine serum proteome despite the potential for biomarker discovery and comparative disease analysis. Establishing serum proteomic signatures in healthy dogs and dogs with CVD will benefit for understanding the aetiology of disease in dogs, identify putative biomarkers and provide models of comparative human disease. Circulating biomarkers are important for understanding of the mechanisms of cardiovascular disease and high incidence of CVD in dogs prioritizes the search for novel biomarkers.

Effect of feline characteristics on plasma N-terminal-prohormone B-type natriuretic peptide concentration and comparison of a point-of-care test and an ELISA test

BACKGROUND

Increased plasma concentration of N-terminal-prohormone B-type natriuretic peptide (NT-proBNP) can be detected in cats with cardiac disease. Potential effects of feline characteristics on NT-proBNP concentration may influence clinical usefulness.

OBJECTIVES

To evaluate potential effects of feline characteristics on NT-proBNP plasma concentration and to compare NT-proBNP plasma concentrations in healthy cats with results in hypertrophic cardiomyopathy (HCM) cats with or without left atrial enlargement (LAE) using an ELISA and a point-of-care test (POCT), and assess if POCT results reflect ELISA results.

ANIMALS

One hundred healthy cats of 3 breeds and 39 HCM cats were included.

METHODS

Diseases other than HCM were excluded by physical examination, blood pressure measurement, echocardiography, hematology, and serum biochemistry.

RESULTS

Higher NT-proBNP concentrations were found in males than in females in healthy (P = .005) and in HCM cats (P = .0021), but breed had no effect on NT-proBNP concentrations. Using ≥100 pmol/L as a cutoff for abnormal samples, ELISA and POCT had similar sensitivity (SE; 72 and 74%) and specificity (SP; 97 and 98%) for detecting cats with HCM, cats with HCM and LAE (SE, both 100%; SP, 97 versus 98%), and cats with HCM without LAE (SE, both 69%; SP, 97 versus 98%), respectively, when compared to healthy cats.

CONCLUSIONS AND CLINICAL IMPORTANCE

Breed had no effect on plasma NT-proBNP concentrations, but higher concentrations were found in male than in female cats. The ELISA and POCT had similar SE and SP for detecting HCM. Both tests could identify all HCM cats with LAE but not all HCM cats without LAE.

Effect of Pimobendan on NT-proBNP and c troponin I before and after a submaximal exercise test in dogs with preclinical mitral valve disease without cardiomegaly - a randomised, double-blinded trial

Background

Exercise testing in conjunction with measurement of cardiac biomarkers NT-proBNP and cTnI is a useful tool for monitoring the effect of treatment on cardiac patients. Administering Pimobendan in dogs with degenerative mitral valve disease (DMVD) and cardiomegaly results in delaying the onset of clinical symptoms and prolonging life. Its effect in dogs with DMVD without cardiomegaly has not been well examined. The aim of the current study was to investigate the effect of administering Pimobendan in dogs with DMVD without cardiomegaly using exercise testing in conjunction with measuring cardiac biomarkers in addition to echocardiography.

Twenty-one dogs with asymptomatic DMVD without echocardiographic signs of cardiomegaly participated in a randomised, double-blinded trial. Dogs were divided into a Pimobendan-group (n = 11) and a placebo-group (n = 10) in a double-blinded study design and underwent a standardised submaximal exercise test (SSET). One dog in the Pimobendan-group was retrospectively removed from the study after being diagnosed with Leishmaniosis. Cardiac biomarkers NT-proBNP and cTnI were measured before and after exercise. Follow-up appointments were performed at days 90 and 180.

Results

Dogs in the Pimobendan-group had significantly lower post-exercise NT-proBNP-levels after being administered Pimobendan than at the beginning of the study. They also had lower pre- and post-exercise-NT-proBNP-levels than those dogs in the placebo-group. There was neither a significant difference regarding the measured cTnI levels nor an increase in cTnI between the groups at any time.

Conclusions

Pimobendan lowers NT-proBNP in dogs with presymptomatic mitral valve disease without cardiomegaly before and after submaximal exercise. This indicates a reduction in cardiac wall stress. If dogs with asymptomatic DMVD without cardiomegaly benefit from treatment with Pimobendan (for example, through a longer survival time) warrants further investigation.

Prognostic factors in dogs with presumed degenerative mitral valve disease attending primary-care veterinary practices in the United Kingdom

Background

Prognostic risk factors were identified for dogs with degenerative mitral valve disease (DMVD) monitored by veterinary cardiologists. The value of these measurements has not been determined in the wider primary care setting.

Objectives

To evaluate whether plasma cardiac biomarkers and data obtained from routine history‐taking and physical examination are predictive of survival in dogs with DMVD attending primary care practice.

Animals

Eight‐hundred and ninety‐three dogs with a presumptive diagnosis of DMVD recruited from 79 primary care veterinary practices in the United Kingdom.

Methods

Prospective cohort study. Primary care veterinary practitioners recorded clinical data. Plasma N‐terminal pro B‐type natriuretic peptide (NT‐proBNP) and cardiac troponin I (cTnI) were measured at presentation. Cox regression models evaluated associations between risk factor variables and hazard of death (all‐cause mortality and cardiac‐related death). Flexible parametric models generated predicted survival probabilities for dogs with different combinations of prognostic risk factor variable values.

Results

Dogs with higher NT‐proBNP and cTnI concentrations, higher heart rates, older dogs, females, and those reported to be exercise intolerant, dyspneic, and diagnosed with selected comorbidities had an increased hazard of death due to any cause. Dogs with higher concentrations of plasma biomarkers, higher heart rates, and heart murmur intensities, those with exercise intolerance and those receiving potent diuretics had a higher hazard of cardiac‐related death.

Conclusions and Clinical Importance

Cardiac biomarkers and key clinical findings identified in this study can help primary care veterinary practitioners identify dogs with DMVD that are at highest risk of death.

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.

Clinical use of submaximal treadmill exercise testing and assessments of cardiac biomarkers NT-proBNP and cTnI in dogs with presymptomatic mitral regurgitation

Exercise intolerance is the first symptom of heart disease. Yet an objective and standardised method in canine cardiology to assess exercise capacity in a clinical setting is lacking. In contrast, exercise testing is a powerful diagnostic tool in humans, providing valuable information on prognosis and impact of therapeutic intervention. To investigate whether an exercise test reveals differences between dogs with early stage mitral regurgitation (MR) and dogs without cardiac disease, 12 healthy beagles (healthy group, HG) and 12 dogs with presymptomatic MR (CHIEF B1 / B2, patient group, PG) underwent a six-stage submaximal exercise test (ET) on a motorised treadmill. They trotted in their individual comfort speed for three minutes per stage, first without incline, afterwards increasing it by 4% for every subsequent stage. Blood samples were taken at rest and during two 3-minute breaks in the course of the test. Further samples were taken after the completion of the exercise test and again after a 3-hour recovery period. Measured parameters included heart rate, lactate and the cardiac biomarkers N-terminal pro-B-Type natriuretic peptide and cardiac Troponin I. The test was performed again under the same conditions in the same dogs three weeks after the first trial to evaluate individual repeatability. Cardiac biomarkers increased significantly in both HG and PG in the course of the test. The increase was more pronounced in CHIEF B1 / B2 dogs than in the HG. N-terminal pro-B-Type natriuretic peptide increased from 435 ± 195 to 523 ± 239 pmol/L (HG) and from 690 to 815 pmol/L (PG). cTnI increased from 0.020 to 0.024 ng/mL (HG) and from 0.06 to 0.08 ng/ml (PG). The present study provides a method to assess exercise-induced changes in cardiac biomarkers under clinical conditions. The increase of NT-proBNP and cTnI is more pronounced in dogs with early-stage MR than in healthy dogs. Results indicate that measuring the parameters before and after exercise is adequate and taking blood samples between the different stages of the ET does not provide additional information. Also, stress echocardiography was inconclusive. It can be concluded that exercise testing, especially in combination with measuring cardiac biomarkers, could be a helpful diagnostic tool in canine cardiology.

N-terminal-pro brain natriuretic peptides in dogs and cats: A technical and clinical review

Biomarkers are quantitative indicators of biological processes performed by an organ or system. In recent years, natriuretic peptides (NPs) have emerged as important tools in the diagnosis and therapeutic monitoring of heart diseases. Research has shown that serum and plasma levels of N-terminal pro brain NP (NT-proBNP) in dogs and cats are the only biomarkers that afford to diagnose and monitor congestive processes and, indirectly, the myocardial function of small animals. The present review discusses the peer-reviewed specialized literature about NT-proBNP and presents and compares the potential clinical applications of this NP in veterinary medicine of small animals, considering diagnosis, follow-up, and prognosis of myocardial or systemic diseases. The relevance of NT-proBNP is associated with sample stability, easy determination in laboratory, sensitivity, accuracy, and the possibility to analyze myocardial function. These advantages are specially important when NT-proBNP is compared with other cardiac biomarkers, mostly those that indicate the integrity of the myocardial cell. Fast NT-proBNP assays are marketed today and may be used in association with complementary tests. Together, these methods are an important source of information in differential diagnosis of heart and lung diseases as well in the early diagnosis of cardiopathy in dogs and cats, proving valuable tools in treatment and prognosis.

Cardiac Troponin I and Amino-Terminal Pro B-Type Natriuretic Peptide in Dogs With Stable Chronic Kidney Disease

Background

Increased concentrations of N‐terminal pro B‐type natriuretic peptide (NT‐proBNP) and cardiac troponin I (cTnI) in dogs with azotemia have been documented. Knowledge of mechanisms behind increased concentrations of cardiac biomarkers in dogs with azotemia is warranted for correct interpretation of test results.

Objectives

The aim of the article was to investigate possible associations between plasma concentrations of cTnI and NT‐proBNP, respectively, and patient characteristics, glomerular filtration rate (GFR), a plasma volume factor (PVF) derived from scintigraphic examination (PVf), systolic blood pressure (SBP), selected hematologic and biochemical variables, and echocardiographic measurements in dogs with stable chronic kidney disease (CKD) and in healthy dogs.

Animals

Fifty student‐, staff‐, and client‐owned dogs were included. Twenty‐three of the dogs were healthy and 27 were diagnosed with CKD.

Methods

In this cross‐sectional observational study, dogs with a previous diagnosis of CKD and healthy control dogs were included. At inclusion, all dogs were characterized by physical examination, repeated blood pressure measurements, complete urinalysis, hematology and biochemistry panel, echocardiography, abdominal ultrasound examination of the entire urinary tract, and scintigraphic examination for measurement of GFR.

Results

Plasma volume factor and PCV were independently associated with NT‐proBNP (Radj2 = 0.42; P < .0001). Age, body weight (BW), and SBP were independently associated with cTnI (Radj2 = 0.50; P < .0001).

Conclusions and Clinical Importance

Neither NT‐proBNP nor cTnI concentrations were independently associated with measured GFR. Thus, findings were not suggestive of passive accumulation of either marker, suggesting that increased circulating concentrations of cTnI and NT‐proBNP can be interpreted similarly in dogs with stable CKD as in dogs without CKD.

Associations of rs3918242 and rs2285053 MMP-9 and MMP-2 polymorphisms with the risk, severity, and short- and long-term complications of degenerative mitral valve diseases: a 4.8-year prospective cohort study

BACKGROUND

Degenerative forms of mitral valve diseases (MVDs) are very complex pathologies. Thus, it is difficult to make generalizations about the disease pathways or genetic risk factors contributing to these diseases. However, a key role of metalloproteinases (MMPs) in their pathophysiology is emerging. Thus, we performed for the first time a perspective study to assess eventual associations of some functional single nucleotide polymorphisms (SNPs) in MMP-2 and MMP-9 genes with the MVD risk, symptom severity, and short- and long-term (4.8 years) complications.

MATERIALS AND METHODS

For this purpose, 90 patients and two control groups were genotyped for rs3918242, rs243865, and rs2285053 MMP-2 and MMP-9 gene SNPs, and systemic levels of pro-atrial natriuretic peptide (pro-ANP) and two enzymes were quantified and correlated to genotypes of MMP-2 and MMP-9 SNPs studied. In addition, associations between these SNPs and symptom severity and short- and long-term (4.8 years) complications were evaluated.

RESULTS

Interestingly, rs3918242 MMP-9 and rs2285053 MMP-2 SNPs were significantly represented in cases than two control groups and were associated with a higher MVD risk, as demonstrated using dominant/recessive models. Cases stratified for NYHA symptoms and particularly those NYHA III+IV with rs3918242 CT+TT MMP-9 and rs2285053CT+TT genotypes also showed higher severity related to significant higher systemic levels of MMP enzymes and pro-ANP at enrolment and 4.8 follow-up times. In addition, cases with these genotypes and particularly those NYHA III+IV had a very significant percentage of complications, particularly at the 4.8 follow-up. Surprisingly, 20% of patient controls developed MVD at 4.8-year follow-up and were carriers of these genotypes.

CONCLUSION

Thus, the associations observed seem to suggest that the two SNPs might represent useful biomarkers and targets for preventing and monitoring MVDs and developing personalized treatments, consenting a more appropriate management and outcome.

Serum Levels of Cardiac Markers NT-proANP and NT-proBNP in Brachycephalic bitches at Different Gestational Stages

The aim of this study was to determine serum levels of natriuretic peptide precursors (NT-proANP and NT-proBNP) during pregnancy in brachycephalic bitches. Fifteen healthy multiparous bitches were selected for this prospective study. Serum levels of NT-proANP and NT-proBNP were measured during anoestrous and at 14, 35, 42, 49 and 56 days (2nd, 5th, 6th, 7th and 8th weeks) of pregnancy. Fourteen animals had normal gestations, and one bitch developed single foetus syndrome. The natriuretic peptide levels of this animal were not included in this study; however, it is important to report that its NT-proANP levels were four times greater than those of normal patients. There was no significant difference (p = 0.072) in NT-proBNP levels between anoestrous (0.20 ± 0.10 ng/ml) and the different pregnancy weeks (0.27 ± 0.12 ng/ml). There was a positive correlation (p < 0.0001) between NT-proANP and gestational age, and the levels of this marker increased significantly (p < 0.0001) during the 6th (0.26 ± 0.06 ng/ml), 7th (0.28 ± 0.04 ng/ml) and 8th weeks (0.29 ± 0.05 ng/ml) when compared to anoestrous (0.18 ± 0.02 ng/ml). NT-proANP serum levels are correlated with gestational development and may be indicative of cardiovascular adaptation in canine brachycephalic pregnancy.

Basal plasma concentrations of N-terminal pro-B-type natriuretic peptide in clinically healthy adult small size dogs: effect of body weight, age, gender and breed, and reference intervals

Plasma NT-proBNP has previously been evaluated in dogs with degenerative mitral valve disease (DMVD). However, reference intervals (RI) established according to the Clinical Laboratory and Standards Institute (CLSI) recommendations have never been provided. The objectives of this prospective study were to assess effects of breed, body weight, age, and sex on plasma NT-proBNP, and to establish RI according to CLSI for this biomarker in a large population of dogs predisposed to DMVD. 183 Healthy small-sized dogs from 7 breeds were included. Assays were performed by ELISA. Effects of covariates were tested using a general linear model. Although a sex effect was demonstrated (P=0.01), no significant effect of breed, body weight or age was shown. The proposed RI was 157-2842 pmol/L. 7% of dogs had plasma NT-proBNP >2617 pmol/L, and were considered as outliers despite normal cardiovascular examination. In conclusion, plasma NT-proBNP may be high in a few healthy small-sized dogs.