Canine degenerative myxomatous mitral valve disease: natural history, clinical presentation and therapy

Iron parameters analysis in dogs with myxomatous mitral valve disease

BACKGROUND

Myxomatous mitral valve disease (MMVD) is the most common acquired cardiovascular disease in small breed dogs. In contrast to human patients with heart failure (HF), iron deficiency (ID) prevalence in dogs with MMVD is weakly known. The study aimed to assess the usability of ID markers in serum and reticulocyte parameters from whole blood of dogs with MMVD to evaluate early ID symptoms.

RESULTS

Sixty-eight dogs (43 male and 25 female) were included in the study. MMVD dogs were assigned according to the 2019 ACVIM guidelines for groups B1 (n = 9), B2 (n = 10), C (n = 27) and D (n = 10). Groups were also combined into B1 and B2 as non-symptomatic HF and C with D as symptomatic HF. Healthy controls were 12 dogs. Serum iron concentration below the reference range in dogs with MMVD was 12.5%. Other ID indices, such as %SAT, UIBC, and TIBC were similar in the MMVD groups and healthy controls (p > 0.05 for all parameters). Statistical comparison between control group and 4 groups of different stages of MMVD showed that significant differences occur only in serum transferrin. The assessment of ferritin and soluble transferrin receptors using Western Blotting did not show differences between control (n = 7) and MMVD (n = 33) dogs. Study has shown positive correlation between ID parameters and echocardiographic indices such as LA/Ao and LVIDdN, and some biochemical parameters. A significant increase in reticulocytes percentage, assessed manually, was observed in the HF group of animals (p = 0.027) compared to the control group.

CONCLUSIONS

Studies have shown that ID parameters in serum are not significantly different in dogs with MMVD compared to healthy dogs. However, there is a clear correlation between atrial size and normalised left ventricular size to body size and some biochemical parameters, including ID parameters and therefore the severity of MMVD.

Proteomic analysis of the serum in dogs with pulmonary hypertension secondary to myxomatous mitral valve disease: the preliminary study

Background

Pulmonary hypertension (PH) is a common complication in dogs with myxomatous mitral valve disease (MMVD), characterized by elevated blood pressure in pulmonary artery. Echocardiography is a reliable technique for PH diagnosis in veterinary medicine. However, it is limited to use as an early detection method. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has found extensive application in the discovery of serum protein biomarkers for various diseases. The objective of this study was to identify serum proteins in healthy control dogs and MMVD dogs both with and without PH using LC-MS/MS.

Materials and methods

In this research, a total of 81 small-breed dogs participated, and they were categorized into three groups: the control (n = 28), MMVD (n = 24) and MMVD+PH (n = 29) groups. Serum samples were collected and analyzed by LC-MS/MS.

Results

Differentially expressed proteins were identified, and the upregulated and downregulated proteins in MMVD+PH group including Myomesin 1 (MYOM1) and Histone deacetylase 7 (HDAC7), Pleckstrin homology domain containing M3 (PLEKHM3), Diacylglycerol lipase alpha (DAGLA) and Tubulin tyrosine ligase like 6 (TTLL6) were selected as proteins of interest in MMVD dogs with PH.

Conclusion

Different types of proteins have been identified in healthy dogs and MMVD dogs with and without PH. Additional studies are needed to investigate the potential of these proteins as biomarkers for PH in dogs with MMVD.

Mitral valve transcriptome analysis in thirty-four age-matched Cavalier King Charles Spaniels with or without congestive heart failure caused by myxomatous mitral valve disease

We here report the results of a mitral valve transcriptome study designed to identify genes and molecular pathways involved in development of congestive heart failure (CHF) following myxomatous mitral valve disease (MMVD) in dogs. The study is focused on a cohort of elderly age-matched dogs (n = 34, age ~ 10 years) from a single breed-Cavalier King Charles Spaniels (CKCS)-with a high incidence of MMVD. The cohort comprises 19 dogs (10♀, 9♂) without MMVD-associated CHF, and 15 dogs (6♀, 9♂) with CHF caused by MMVD; i.e., we compare gene expression in breed and age-matched groups of dogs, which only differ with respect to CHF status. We identify 56 genes, which are differentially expressed between the two groups. In this list of genes, we confirm an enrichment of genes related to the TNFβ-signaling pathway, extracellular matrix organization, vascular development, and endothelium damage, which also have been identified in previous studies. However, the genes with the greatest difference in expression between the two groups are CNTN3 and MYH1. Both genes encode proteins, which are predicted to have an effect on the contractile activity of myocardial cells, which in turn may have an effect on valvular performance and hemodynamics across the mitral valve. This may result in shear forces with impact on MMVD progression.

Cardiac Disease and Screening in Breeding Dogs

Acquired and congenital heart diseases are relatively common in dogs, particularly in certain breeds. Modes of inheritance and genetic causes have been established for several cardiac diseases within various breeds. Breed screening is used to try and reduce the prevalence of certain canine cardiac diseases. Although breed screening seems to help reduce the prevalence of canine heart disease, the outcomes of specific breeding programs are variable and depend on multiple factors.

A survey on dogs with valvular disease flying to Japan for operation

In small-breed dogs, myxomatous mitral valve disease (MMVD) is a common disease which may lead to chronic heart failure. Mitral valve repair is an optimal surgical treatment that is currently available in limited veterinary facilities globally because it requires a special surgery team and specific devices. Therefore, some dogs must travel overseas to undergo this surgery. However, a question arises regarding the safety of dogs when traveling by air with a heart disease. We aimed to evaluate the effect of flight journey on dogs with mitral valve disease, including survival rates, symptoms during the trip, laboratory test results, and operational outcomes. All dogs stayed near the owner in the cabin during the flight. The survival rate after the flight was 97.5% in 80 dogs. The surgical survival rates (96.0% and 94.3%) and hospitalization periods (7 days and 7 days) were similar between overseas and domestic dogs. This report shows that taking air flights in the cabin may not have a significant effect on dogs with MMVD, on the premise that their overall conditions are stable under cardiac medication.

Evaluation of the Corrected QT Interval with Bazett’s Method in Cavalier King Charles Spaniel Dogs with Myxomatous Mitral Valve Disease

Myxomatous mitral valve disease (MMVD) is one of the most common heart diseases in dogs. The disease progresses faster in Cavalier King Charles Spaniel (CKCS) dogs and occurs at an earlier age. QT interval length reflects abnormalities in ventricular repolarization which may predispose to the formation of fatal arrhythmias such as torsades de pointes. A fast and accurate assessment is therefore essential. The study aimed to examine the changes in QT duration in MMVD cases of CKCS and to calculate the corrected QT durations with Bazett’s formula in various stages of the disease. The study included 20 CKCS dogs of both genders, various ages and weights, and different stages of MMVD (n=6 in B1 stage, n=6 in B2 stage, and n=8 in C stage), and 5 healthy CKCS which were included in the control group. Clinical, radiological, hematological, biochemical, echocardiographic, and electrocardiographic examinations were performed. The corrected QT interval duration in the MMVD group was longer than the control (p<0.05). However, there was no significant difference between B1, B2, and C. It was concluded that the corrected QT interval can give a significant distinction between healthy and MMVD CKCS dogs.

N-terminal pro-B-type natriuretic peptide levels in normotensive and hypertensive dogs with myxomatous mitral valve disease stage B

BACKGROUND

Systemic hypertension affects the heart, and to the best of our knowledge, no study has investigated the effects of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in dogs with myxomatous mitral valve disease (MMVD) stage B and systemic hypertension. This study aimed to investigate the blood level of NT-proBNP and assess the selected echocardiographic variables in dogs with MMVD stage B according to the presence of systemic hypertension or normal blood pressure and in dogs without MMVD.

RESULTS

The study group comprised 37 dogs with stage B MMVD (normotensive group, n = 30; systemic hypertension group, n = 7) and 13 dogs without MMVD. We evaluated NT-proBNP, blood pressure, complete blood count (CBC), and serum chemistry in all 50 dogs. We performed electrocardiography, radiography, and echocardiography on 44 dogs (37 dogs with MMVD and 7 dogs without MMVD). The NT-proBNP concentrations showed significant intergroup differences (p < 0.001). Normotensive dogs with MMVD stage B (median [interquartile range]: 1083.5 [574.8-1912.8] pmol/L) and hypertensive dogs with MMVD stage B (2345.0 [1812.5-2533.0] pmol/L) showed significantly higher NT-proBNP concentrations than dogs without MMVD (504 [430-774] pmol/L, p = 0.009 and p < 0.001, respectively), and dogs in the systemic hypertension group showed significantly higher NT-proBNP concentrations than those in the normotensive group (p = 0.046). Mitral valve regurgitation velocity was significantly higher in dogs in the systemic hypertension group (6.11 [6.07-6.24] m/s) than in those in the normotensive group (5.53 [5.17-5.95] m/s, p = 0.006). The left atrial to aortic root ratio (LA/Ao), E-peak velocity, and left ventricular end-diastolic internal diameter corrected for body weight (LVIDDN) were significantly lower in dogs without MMVD than in dogs with MMVD stage B.

CONCLUSIONS

These findings suggest that NT-proBNP concentrations are higher in dogs with MMVD stage B with systemic hypertension than in normotensive dogs with MMVD stage B. Therefore, clinicians should be aware that NT-proBNP could be elevated in the presence of systemic hypertension.

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.

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.

Key nutrients important in the management of canine myxomatous mitral valve disease and heart failure

The most common cause of heart failure in dogs is myxomatous mitral valve disease (MMVD), which accounts for approximately 75% of canine heart disease cases and is especially common in smaller dogs. Although low-sodium diets have been recommended for humans with heart diseases for decades, there is little evidence to support this practice in dogs. In recent years, however, it has become clear that other nutrients are important to heart health. Dogs with heart disease secondary to MMVD experience patterns of metabolic changes that include decreased mitochondrial energy metabolism and ATP availability, with increased oxidative stress and inflammation. These changes occur early in disease and progress with worsening heart disease. Key nutrients that may support normal function and address these changes include omega-3 fatty acids, medium-chain triglycerides, magnesium, antioxidants including vitamin E and taurine, and the amino acids methionine and lysine. The long-chain omega-3 fatty acids provide anti-inflammatory, antithrombotic, and other benefits. Medium-chain fatty acids and ketones derived from medium-chain triglycerides provide an alternative energy source for cardiac mitochondria and help reduce free radical production. Magnesium supports mitochondrial function, normal cardiac rhythm, and provides other benefits. Both vitamin E and taurine counter oxidative stress, and taurine also has direct cardiac benefits. Dogs with MMVD have reduced plasma methionine. Methionine and lysine are important for carnitine production as well as other functions. This article reviews the evidence supporting the functions and benefits of these and other nutrients in MMVD and other cardiac conditions.

Methods of Radiographic Measurements of Heart and Left Atrial Size in Dogs with and without Myxomatous Mitral Valve Disease: Intra- and Interobserver Agreement and Practicability of Different Methods

Dogs suffering from Myxomatous Mitral Valve Disease (MMVD) show a potential heart enlargement, especially in the left atrium, detectable by radiography. Due to digital radiography, different radiographic measurements estimate cardiac size quite uncomplicatedly. The Vertebral Heart Size (VHS), Radiographic Left Atrial Dimension (RLAD), Left Atrial Width (LAWidth), and the Vertebral Left Atrial Size (VLAS) used anatomical landmarks for measuring cardiac size in relation to the vertebral column. This study aimed to compare VHS, RLAD, LAWidth, and VLAS measured in conventional and inverted radiographs by veterinarians with different levels of experience in healthy dogs and dogs with MMVD. The reliability and user-friendliness of these measurements were evaluated, and the staging was compared to the echocardiography staging. A total of 50 unaffected dogs and 150 dogs with MMVD in stages B1, B2, and C were assessed. Three veterinarians with different levels of experience examined 200 conventional radiographs and their corresponding inverted radiographs blinded to the echocardiographic and clinical examination results. Analyses were performed to compare the measurements’ grading and determine anatomical landmarks with measurement difficulties. Additionally, inter- and intraobserver agreement was assessed using intraclass correlation coefficient, and the agreement between radiographic and echocardiographic staging was compared using the kappa coefficient. The VHS, LAWidth, and VLAS were easier to define than the RLAD. The interobserver agreement was almost perfect for VHS (0.962) and good for the other radiographic measurements (RLAD: 0.778, LAWidth: 0.772, VLAS: 0.858). The VHS assigned the most dogs to the correct stage. However, VHS, RLAD, LAWidth, and VLAS presented an almost perfect intraobserver agreement. The dorsal left atrial margin of the RLAD was the most difficult measurement point to identify. The VHS is the most reproducible radiographic method for measuring the canine heart size and shows the highest agreement with echocardiography. An observer-related influence could be detected for RLAD, LAWidth, and VLAS.

Comparison of different radiographic scores with associated echocardiographic measurements and prediction of heart enlargement in dogs with and without myxomatous mitral valve disease

INTRODUCTION

Staging of myxomatous mitral valve disease (MMVD) requires an echocardiographic examination along with thoracic radiographs. The aims of this study were to calculate mean values for radiographic scores vertebral heart size (VHS), left atrial width (LA_Width), radiographic left atrial dimension (RLAD), and vertebral left atrial size (VLAS) in conventional and grayscale inverted images in healthy dogs and dogs with different stages of MMVD, and to find cutoff values for a stage assignment.

ANIMALS

One hundred fifty dogs in different stages of MMVD and 50 unaffected dogs were evaluated.

METHODS

Radiographic scores, echocardiographic left atrium-to-aorta ratio and normalized left ventricular internal dimension at end-diastole, and results of a clinical examination were obtained. Analyses were performed to evaluate the correlation between radiographic scores and echocardiographic values, to determine cutoff values for a radiographic stage assignment, and to compare measurements in conventional and inverted radiographs.

RESULTS

After excluding breed-specific higher VHS, the means of VHS, LA_Width, RLAD, and VLAS were similar in the control group and stage B1. All radiographic scores increased in stages B2 and C. The cutoff values identifying heart enlargement, and therefore differentiating stages B1 and B2, were 11.0 for VHS, 1.8 for LA_Width, 2.0 for RLAD, and 2.3 for VLAS. Besides RLAD, scores were similar in conventional and inverted radiographs.

CONCLUSION

Cutoff values for the different radiographic scores for stage assignment were calculated. Radiographic cardiac scores using either conventional or inverted grayscale could be a tool to differentiate between different stages of MMVD when echocardiography is unavailable.

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

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

Circulating MiR-30b-5p is upregulated in Cavalier King Charles Spaniels affected by early myxomatous mitral valve disease

There is a growing interest in developing new molecular markers of heart disease in young dogs affected by myxomatous mitral valve disease. The study aimed to measure 3 circulating microRNAs and their application as potential biomarkers in the plasma of Cavalier King Charles Spaniels with early asymptomatic myxomatous mitral valve disease. The hypothesis is that healthy Cavalier King Charles Spaniels have different microRNA expression profiles than affected dogs in American College of Veterinary Internal Medicine (ACVIM) stage B1. The profiles can differ within the same class among subjects of different ages. This is a prospective cross-sectional study. Thirty-three Cavalier King Charles Spaniels in ACVIM stage B1 were divided into three groups (11 younger than 3 years, 11 older than 3 years and younger than 7 years, and 11 older than 7 years), and 11 healthy (ACVIM stage A) dogs of the same breed were included as the control group. Three circulating microRNAs (miR-1-3p, miR30b-5p, and miR-128-3p) were measured by quantitative real-time PCR using TaqMan® probes. Diagnostic performance was evaluated by calculating the area under the receiver operating curve (AUC). MiR-30b-5p was significantly higher in ACVIM B1 dogs than in ACVIM A subjects, and the area under the receiver operating curve was 0.79. According to the age of dogs, the amount of miR-30b-5p was statistically significantly higher in group B1<3y (2.3 folds, P = 0.034), B1 3-7y (2.2 folds, P = 0.028), and B1>7y (2.7 folds, P = 0.018) than in group A. The area under the receiver operating curves were fair in discriminating between group B1<3y and group A (AUC 0.780), between B1 3-7y and A (AUC 0.78), and good in discriminating between group B1>7y and A (AUC 0.822). Identifying dogs with early asymptomatic myxomatous mitral valve disease through the evaluation of miR-30b-5p represents an intriguing possibility that certainly merits further research. Studies enrolling a larger number of dogs with preclinical stages of myxomatous mitral valve disease are needed to expand further and validate conclusively the preliminary findings from this report.

Combination of the Modified Loop Technique and De Vega Annuloplasty in Dogs with Mitral Regurgitation

Background: Detailed surgical techniques for treating canine mitral regurgitation have not been previously reported. Method: This case series included six consecutive client-owned dogs with mitral regurgitation. All dogs underwent a combined protocol, including the modified loop technique and De Vega annuloplasty (MODEL surgery), in 2021. Artificial loops covering 80% of the length of the strut chordae tendineae were used for chordal replacement. Mitral annuloplasty was subjectively performed, targeting the circumference of the septal leaflet. Results: The breeds were Chihuahua-mixed breed, Spitz, Pomeranian, Cavalier King Charles Spaniel, and Chihuahua, with average ages and weights of 11.4 ± 2.3 years and 5.49 ± 2.98 kg, respectively. The aortic cross-clamp, pumping, and surgery times were 64.0 ± 7.5 min, 168.5 ± 39.1 min, and 321.0 ± 53.1 min, respectively. After MODEL surgery, left atrial-to-aortic ratios significantly decreased from 2.20 ± 0.18 to 1.26 ± 0.22 (p < 0.01), and left ventricular end-diastolic internal diameter normalized to body weight significantly decreased from 2.03 ± 0.26 to 1.48 ± 0.20 (p < 0.01). In all cases, the clinical signs disappeared or improved significantly. Conclusions: MODEL surgery increased mitral valve coaptation, normalized heart sizes, and significantly improved clinical signs in dogs with mitral regurgitation.

Reference Values of M-mode Echocardiographic Parameter in Adult Toy Breed Dogs

Introduction:

Myxomatous mitral valve disease (MMVD) is one of the most common heart diseases in dogs, and there is a dearth of reports that have investigated reference values for left ventricular end-diastolic internal diameter corrected for body weight (LVIDDN) exclusively in toy breeds.

Animals

Eighty-six client-owned healthy dogs weighing <5 kg, including Toy Poodles, Chihuahuas, Yorkshire Terriers, Papillon, and other small breeds or small mixed breeds (mixed breed, Pomeranian, dachshund, Shih Tzu, and Maltese). In this retrospective single-center study, data were collected from dogs attending clinic for annual checkup between April 2014 and March 2021.

Materials and Methods

Experienced echocardiographers performed transthoracic echocardiography, with reference ranges established using healthy dogs. Measurements of body weight (BW), heart rate, and several echocardiographic variables were obtained. The association between BW and echocardiographic parameters was assessed by linear regression analyses. M-mode measurements were obtained and normalized using equations developed from the regression analyses.

Results

The LVIDDN value for 95% of dogs weighing <5 kg was achieved by dividing the M-mode measurement by BW raised to the power 0.332. The upper limit of the prediction interval for breeds weighing <5 kg was much lower than the value currently applied.

Conclusions

We propose a reference LVIDDN value of ≥1.6 for the diagnosis of stage B2 MMVD in toy breed dogs. The results of our study will guide clinicians in deciding when to start treatment for MMVD in small breed dogs.

Comparison of Intestinal Microbiota Between Healthy and MMVD Chihuahuas Using 16S rRNA Gene Amplicon Sequencing

Myxomatous mitral valve disease (MMVD) is the most common cause of congestive heart failure in dogs, and although complications of MMVD to the lungs and kidneys have been identified, complications to the gut are less well understood. The intestinal microbiota is an important factor in the gut, and although the association between heart disease and the intestinal microbiota has been shown in human medicine, it is unknown in dogs. The study aimed to evaluate the relationship between MMVD and gut microbiota. A total of 69 healthy Chihuahuas and Chihuahuas with MMVD were evaluated for cardiac health by echocardiography and chest radiography and grouped according to ACVIM guidelines. Fecal samples were collected from all cases and 16S rRNA sequencing was used to reveal the intestinal microbiota. There were significant differences in LA/Ao, LVIDd, E vel, VHS, and VLAS with the severity of ACVIM. On the other hand, there were no significant differences in the diversity and composition of gut microbiota among the groups. The present study did not identify the effects of MMVD on the gut microbiota.

Management of Chronic Congestive Heart Failure Caused by Myxomatous Mitral Valve Disease in Dogs: A Narrative Review from 1970 to 2020

Simple Summary

Myxomatous mitral valve disease (MMVD) is the most common acquired cardiovascular disease in dogs. The progression of the disease and the increasing severity of valvular regurgitation cause a volume overload of the left heart, leading to left atrial and ventricular remodeling and congestive heart failure (CHF). The treatment of chronic CHF secondary to MMVD in dogs has not always been the same over time. In the last fifty years, the drugs utilized have considerably changed, as well as the therapeutic protocols. Some drugs have also changed their intended use. An analysis of the literature concerning the therapy of chronic heart failure in dogs affected by this widespread degenerative disease is not available; a synthesis of the published literature on this topic and a description of its current state of art are needed. To the authors’ knowledge, a review of this topic has never been published in veterinary medicine; therefore, the aim of this study is to overview the treatments of chronic CHF secondary to MMVD in dogs from 1970 to 2020 using the general framework of narrative reviews.

Abstract

The treatment of chronic congestive heart failure (CHF), secondary to myxomatous mitral valve disease (MMVD) in dogs, has considerably changed in the last fifty years. An analysis of the literature concerning the therapy of chronic CHF in dogs affected by MMVD is not available, and it is needed. Narrative reviews (NRs) are aimed at identifying and summarizing what has been previously published, avoiding duplications, and seeking new study areas that have not yet been addressed. The most accessible open-access databases, PubMed, Embase, and Google Scholar, were chosen, and the searching time frame was set in five decades, from 1970 to 2020. The 384 selected studies were classified into categories depending on the aim of the study, the population target, the pathogenesis of MMVD (natural/induced), and the resulting CHF. Over the years, the types of studies have increased considerably in veterinary medicine. In particular, there have been 43 (24.29%) clinical trials, 41 (23.16%) randomized controlled trials, 10 (5.65%) cross-over trials, 40 (22.60%) reviews, 5 (2.82%) comparative studies, 17 (9.60%) case-control studies, 2 (1.13%) cohort studies, 2 (1.13%) experimental studies, 2 (1.13%) questionnaires, 6 (3.40%) case-reports, 7 (3.95%) retrospective studies, and 2 (1.13%) guidelines. The experimental studies on dogs with an induced form of the disease were less numerous (49–27.68%) than the studies on dogs affected by spontaneous MMVD (128–72.32%). The therapy of chronic CHF in dogs has considerably changed in the last fifty years: in the last century, some of the currently prescribed drugs did not exist yet, while others had different indications.

Myxomatous mitral valve disease in Miniature Schnauzers and Yorkshire Terriers: 134 cases (2007-2016)

OBJECTIVE

To characterize features of myxomatous mitral valve disease (MMVD) in Miniature Schnauzers and Yorkshire Terriers.

ANIMALS

69 Miniature Schnauzers and 65 Yorkshire Terriers, each with MMVD.

PROCEDURES

Medical record data for each dog were collected; the study period was January 2007 through December 2016. If available, radiographic data were evaluated, and a vertebral heart scale score was assigned for each dog. Statistical analysis was performed with Student t and Fisher exact tests.

RESULTS

Compared with Yorkshire Terriers, the prevalence of MMVD was significantly higher in Miniature Schnauzers and affected dogs were significantly younger at the time of diagnosis. Miniature Schnauzers were significantly more likely to have mitral valve prolapse and syncope, compared with Yorkshire Terriers. Yorkshire Terriers were significantly more likely to have coughing and have had previous or current treatment with cardiac medications, compared with Miniature Schnauzers. There was no statistical difference between breeds with regard to abnormally high vertebral heart scale scores or radiographic evidence of congestive heart failure.

CONCLUSIONS AND CLINICAL RELEVANCE

With regard to MMVD, features of the disease among Miniature Schnauzers and Yorkshire Terriers were similar, but there were also a few discernable differences between these 2 breeds and from historical findings for dogs with MMVD of other breeds. Clinical signs at the time of diagnosis differed between the 2 breeds, which may have reflected concurrent breed-specific conditions (sick sinus syndrome or airway disease [eg, tracheal collapse]). Future work should include prospective studies to provide additional information regarding the natural progression of MMVD in these dog breeds.

Angiotensin-converting enzyme inhibitors in preclinical myxomatous mitral valve disease in dogs: systematic review and meta-analysis

To determine the efficacy and adverse events of the administration of angiotensin-converting enzyme inhibitors for the management of preclinical myxomatous mitral valve disease in dogs. A comprehensive search using Pubmed/MEDLINE, LILACS and CAB abstracts databases was performed. Randomised clinical trials that assessed efficacy and adverse events of angiotensin-converting enzyme inhibitors for the management of preclinical myxomatous mitral valve disease in dogs were included. Certainty of evidence was rated using GRADE methods. Four randomised clinical trials were included. While safe, angiotensin-converting enzyme inhibitors administration to dogs with myxomatous mitral valve disease and cardiomegaly results in little to no difference in the risk of development congestive heart failure (high certainty of evidence; relative risk: 1.03; 95% confidence interval: 0.87 to 1.23) and may result in little to no difference in cardiovascular-related (low certainty of evidence; relative risk: 1.01; 95% confidence interval: 0.54 to 1.89) and all-cause mortality (low certainty of evidence; relative risk: 0.93; 95% confidence interval: 0.63 to 1.36). Administration of angiotensin-converting enzyme inhibitors to dogs with myxomatous mitral valve disease without cardiomegaly may result in a reduced risk of congestive heart failure development. However, the range in which the actual effect for this outcome may be, the "margin of error," indicates it might also increase the risk of congestive heart failure development (low certainty of evidence; relative risk: 0.86; 95% confidence interval: 0.54 to 1.35). Administration of angiotensin-converting enzyme inhibitors to dogs with preclinical myxomatous mitral valve disease and cardiomegaly results in little to no difference in the risk of the development of congestive heart failure and may result in little to no difference in cardiovascular-related and all-cause mortality. The certainty of evidence of the efficacy of angiotensin-converting enzyme inhibitors administration to dogs without cardiomegaly was low.

Intestinal Complication With Myxomatous Mitral Valve Diseases in Chihuahuas

The effects of cardiac disease on the intestine have been reported in humans but not in dogs. We investigated the effects of myxomatous mitral valve disease (MMVD), which is capable of causing congestion and tissue hypoperfusion, on the intestine in Chihuahuas, a breed frequently encountered in clinical practice as the preferred breed for MMVD. In this study, 69 Chihuahuas were divided into four groups based on echocardiography and chest radiography: 19 healthy Chihuahuas (H) and 50 Chihuahuas with MMVD classified according to the ACVIM consensus (stage B1, B2, C/D). In all the cases, serum intestinal fatty acid-binding protein (I-FABP) and D/L-lactate concentrations, markers of intestinal mucosal injury, were measured. I-FABP was significantly higher in stage C/D Chihuahuas than in other groups (p < 0.05), and stage B2 was significantly higher than H (p < 0.05). D-lactate was significantly increased in stages B2 and C/D compared to H and stage B1 (p < 0.05). L-lactate was significantly higher in stage C/D Chihuahuas than in any other group (p < 0.05), and stage B2 was significantly higher than that in H and stage B1 (p < 0.05). Intestinal mucosal injury risk was significantly higher in Chihuahuas with heart failure due to MMVD, suggesting that the risk could increase with worsening heart disease. This is the first study to investigate the intestinal complications of MMVD, and further investigations a needed in the future.

Pathology and Advanced Imaging—Characterization of a Congenital Cardiac Defect and Complex Hemodynamics in a Pig: A Case Report

Domestic pigs are widely used in cardiovascular research as the porcine circulatory system bears a remarkable resemblance to that of humans. In order to reduce variability, only clinically healthy animals enter the study as their health status is assessed in entry examination. Like humans, pigs can also suffer from congenital heart disease, such as an atrial septal defect (ASD), which often remains undetected. Due to the malformation of the endocardial cushion during organ development, mitral valve defects (e.g., mitral clefts) are sometimes associated with ASDs, further contributing to hemodynamic instability. In this work, we report an incidental finding of a hemodynamically highly relevant ASD in the presence of incompetent mitral and tricuspid valves, in an asymptomatic, otherwise healthy juvenile pig. In-depth characterization of the cardiac blood flow by four-dimensional (4D) flow magnetic resonance imaging (MRI) revealed a prominent diastolic left-to-right and discrete systolic right-to-left shunt, resulting in a pulmonary-to-systemic flow ratio of 1.8. Severe mitral (15 mL/stroke) and tricuspid (22 mL/stroke) regurgitation further reduced cardiac output. Pathological examination confirmed the presence of an ostium primum ASD and found a serous cyst of lymphatic origin that was filled with clear fluid partially occluding the ASD. A large mitral cleft was identified as the most likely cause of severe regurgitation, and histology showed mild to moderate endocardiosis in the coaptation area of both atrio-ventricular valves. In summary, although not common, congenital heart defects could play a role as a cause of experimental variability or even intra-experimental mortality when working with apparently heathy, juvenile pigs.

A retrospective study of 14 dogs with advanced heart failure treated with loop diuretics and hydrochlorothiazide

Background:

The use of thiazide diuretics is recommended in the American College of Veterinary Internal Medicine guidelines for advanced heart failure due to mitral insufficiency (MI) in dogs. However, there are no large-scale reports of the use of thiazide diuretics in dogs with advanced heart failure.

Aim:

This retrospective study evaluated the therapeutic effect of concomitant hydrochlorothiazide (HTCZ) with loop diuretics in dogs with heart failure.

Methods:

The study included 14 dogs diagnosed with advanced pulmonary edema with MI at two facilities. In all cases, high-dose loop diuretics (torsemide; 0.78–4 mg/kg/day) did not improve pulmonary edema. The results of the echocardiography and renal function tests before and after the administration of HTCZ (0.2–0.84 mg/kg/day) in addition to torsemide were statistically compared.

Results:

The echocardiographic data demonstrated significant improvement in relation to cardiac stress; left atrium to the aorta ratio, normalized left ventricular internal dimension in diastole, and E wave velocity (m/s) after HTCZ administration. However, blood urea nitrogen and creatinine levels increased, and potassium levels decreased, indicating a decline in renal function following HTCZ administration.

Conclusion:

This study suggests that the administration of HTCZ in combination with loop diuretics may be beneficial during advanced heart failure due to MI in dogs. The results can also be extended to patients who are resistant to loop diuretics, resulting in the improvement of cardiac function. However, as the combination of HTCZ and loop diuretics can deteriorate renal function, caution should be exercised prior to making recommendations regarding its use, and renal function should be monitored.

Dogs' Microbiome From Tip to Toe

Microbiota and microbiome, which refers, respectively, to the microorganisms and conjoint of microorganisms and genes are known to live in symbiosis with hosts, being implicated in health and disease. The advancements and cost reduction associated with high-throughput sequencing techniques have allowed expanding the knowledge of microbial communities in several species, including dogs. Throughout their body, dogs harbor distinct microbial communities according to the location (e.g., skin, ear canal, conjunctiva, respiratory tract, genitourinary tract, gut), which have been a target of study mostly in the last couple of years. Although there might be a core microbiota for different body sites, shared by dogs, it is likely influenced by intrinsic factors such as age, breed, and sex, but also by extrinsic factors such as the environment (e.g., lifestyle, urban vs rural), and diet. It starts to become clear that some medical conditions are mediated by alterations in microbiota namely dysbiosis. Moreover, understanding microbial colonization and function can be used to prevent medical conditions, for instance, modulation of gut microbiota of puppies is more effective to ensure a healthy gut than interventions in adults. This paper gathers current knowledge of dogs' microbial communities, exploring their function, implications in the development of diseases, and potential interactions among communities while providing hints for further research.

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.

Use of whole genome analysis to identify shared genomic variants across breeds in canine mitral valve disease

Familial mitral valve prolapse in human beings has been associated with several genetic variants; however, in most cases, a known variant has not been identified. Dogs also have a naturally occurring form of familial mitral valve disease (MMVD) with similarities to the human disease. A shared genetic background and clinical phenotype of this disease in some dog breeds has indicated that the disease may share a common genetic cause. We evaluated DNA from 50 affected dogs from five different dog breeds in a whole genome sequencing approach to identify shared variants across and within breeds that could be associated with MMVD. No single causative genetic mutation was found from the 50 dogs with MMVD. Ten variants were identified in 37/50 dogs around and within the MED13L gene. These variants were no longer associated with MMVD when evaluated with a larger cohort including both affected and unaffected dogs. No high/moderate impact variants were identified in 10/10 miniature poodles, one was identified in 10/10 Yorkshire Terriers and 10/10 dachshunds, respectively, 14 were identified in 10/10 Miniature schnauzers, and 19 in 10/10 CKCS. Only one of these could be associated with the cardiac valve (Chr12:36801705, COL12A1; CKCS) but when evaluated in an additional 100 affected CKCS the variant was only identified in 84/100 affected dogs, perhaps indicating genetic heterogeneity in this disease. Our findings indicate that development of MMVD in the dog may be related to a combination of genetic and environmental factors that impact specific molecular pathways rather than a single shared genetic variant across or within breeds.

Biomechanical-Structural Correlation of Chordae tendineae in Animal Models: A Pilot Study

Simple Summary

The Chordae tendineae are part of the atrioventricular apparatus. They are mainly responsible for the mechanical functions of heart valves. Degenerative mitral valve disease is the most common heart disease in dogs and is responsible for about 75% of cases of heart failure. One of the complications of this disease is Chordae tendineae rupture. It is clinically relevant to better understand the biomechanical and structural properties of CT in order to begin further studies about biomarkers suggesting an episode of CT rupture. Such an episode leads to acute pulmonary oedema and worsens the clinical status of the patient. Information about the biomechanical and structural properties of healthy CT and CT affected by the degenerative process are essential in understanding how CT behave in an in vivo environment.

Abstract

The mitral valve apparatus is a complex structure consisting of the mitral ring, valve leaflets, papillary muscles and Chordae tendineae (CT). The latter are mainly responsible for the mechanical functions of the valve. Our study included investigations of the biomechanical and structural properties of CT collected from canine and porcine hearts, as there are no studies about these properties of canine CT. We performed a static uniaxial tensile test on CT samples and a histopathological analysis in order to examine their microstructure. The results were analyzed to clarify whether the changes in mechanical persistence of Chordae tendineae are combined with the alterations in their structure. This study offers clinical insight for future research, allowing for an understanding of the process of Chordae tendineae rupture that happens during degenerative mitral valve disease—the most common heart disease in dogs.

Metabolomics Analysis Reveals Deranged Energy Metabolism and Amino Acid Metabolic Reprogramming in Dogs With Myxomatous Mitral Valve Disease

Background

Myxomatous mitral valve disease (MMVD), a naturally occurring heart disease, affects 10% to 15% of the canine population. Canine MMVD shares many similarities with human MMVD. Untargeted metabolomics was performed to identify changes in metabolic pathways and biomarkers with potential clinical utilities.

Methods and Results

Serum samples from 27 healthy, 22 stage B1, 18 stage B2 preclinical MMVD dogs, and 17 MMVD dogs with a history of congestive heart failure (CHF) were analyzed. Linear regression analysis identified 173 known metabolites whose concentrations were different among the 4 groups (adjusted P<0.05), of which 40% belonged to amino acid super pathways, while 30% were lipids. More than 50% of significant metabolites were correlated with left atrial diameter but not left ventricular dimension. Acylcarnitines, tricarboxylic acid cycle intermediates, and creatine accumulated in proportion to MMVD severity. α‐Ketobutyrate and ketone bodies were increased as MMVD advanced. Nicotinamide, a key substrate of the main nicotinamide adenine dinucleotide (NAD⁺) salvage pathway, was decreased, while quinolinate of the de novo NAD⁺ biosynthesis was increased in CHF dogs versus healthy dogs. 3‐Methylhistidine, marker for myofibrillar protein degradation, was higher in CHF dogs than non‐CHF dogs. Trimethylamine N‐oxide (TMAO) and TMAO–producing precursors, including carnitine, phosphatidylcholine, betaine, and trimethyllysine, were increased in CHF dogs versus non‐CHF dogs. Elevated levels of uremic toxins, including guanidino compounds, TMAO, and urea, were observed in CHF dogs. Pathway analysis highlighted the importance of bioenergetics and amino acid metabolism in canine MMVD.

Conclusions

Our study revealed altered energy metabolism, amino acid metabolic programming, and reduced renal function in the development of MMVD and CHF. Complex interplays along the heart‐kidney‐gut axis were implicated.

[Patient owner surveys in small animal medicine - importance, benefits and pitfalls in planning, execution and analysis]

OBJECTIVE

In the present study, the benefits and difficulties of planning and conducting patient surveys in veterinary medicine were examined using 2 examples. One focus was placed on the comparison of the subjective assessment and perception of patient owners with regard to long-term investigation of disease progression.

STUDY POPULATION

An owner survey was conducted in dogs with chronic enteropathy (CE) and degenerative mitral valve disease (DMVD). In both surveys, the case system of the Clinic for Small Animals of the University of Veterinary Medicine Hannover was used to identify suitable cases based on appropriate diagnoses. Owners were contacted and invited to complete (digitally or postally) a multipart questionnaire on their dogs. The results of the survey were evaluated regarding their agreement with literature data. Based on the results of this evaluation, the study design, reliability of owner perception and the benefit of the survey were examined critically.

RESULTS

The search in the clinic's case system provided 125 suitable cases for CE and 145 for DMVD. A total of 81 (CE, response rate 64.8 %) and 72 (DMVD, response rate 49,7 %) owners answered the questionnaire. The owners provided considerably different information concerning the diagnostic examination of their animals. While the statements on the course and forms of disease in CE corresponded to the information from the literature, this was not always the case with DMVD.

CONCLUSION AND CLINICAL RELEVANCE

Patient owner surveys may provide important information about disease progression from the owner's perspective. This is particularly valuable in chronic diseases, the management of which requires good owner compliance. An identical approach to patient selection may lead to results differing in their informative value depending on the disease.

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.

Interobserver variability of radiographic methods for the evaluation of left atrial size in dogs

The objectives of this retrospective, observer agreement study were to (a) test variability of radiographic left atrial dimension (RLAD) and vertebral left atrial size (VLAS) measurements among observers with different levels of expertise in thoracic radiology and cardiology, (b) assess whether one method is better than the other in detecting left atrial enlargement (LAE), and (c) assess the agreement among RLAD, VLAS, and American College of Veterinary Internal Medicine (ACVIM) classes. Seventy-four dogs (eight healthy and 66 with mitral valve disease) with thoracic radiographs and echocardiography performed on the same day were reviewed. Thirty showed echocardiographic LAE. Left atrial dimension was quantified using RLAD and VLAS by six different operators with three levels of clinical experience in veterinary cardiology/radiology. Vertebral heart score and fourth thoracic vertebra (T4) were also measured. Differences in T4, vertebral heart score (VHS), RLAD, and VLAS measurements were found among six operators and among the three levels of clinical expertise as well as between veterinary cardiology readers and veterinary radiology readers (P < .05). The area under the receiver operating characteristic (AUC) curve for VHS showed good performances for all observers and level and type of expertise; the AUC for RLAD and VLAS was suboptimal only for the radiology student. Our RLAD and VLAS cutoffs (1.9 and 2.43 v, respectively) were better related to qualitative radiographic than quantitative echocardiographic LAE evaluation. Radiographic LA dimension and VLAS showed an increase proportional to the worsening of the ACVIM class. In conclusion, these results allow us to affirm that RLAD and VLAS are reproducible measurements for detecting LAE. Better performances are associated with clinical expertise and background.

Short-term effects of sildenafil in the treatment of dogs with pulmonary hypertension secondary to degenerative mitral valve disease

Background and Aim:

Pulmonary hypertension (PH) is a common complication of degenerative mitral valve disease (DMVD). Sildenafil, a phosphodiesterase-5 inhibitor, has effects in reducing pulmonary arterial pressure by selectively dilating pulmonary vessels. The study aimed to evaluate the effects of sildenafil in combination with conventional therapy in dogs with PH caused by DMVD.

Materials and Methods:

Fourteen dogs diagnosed with PH secondary to DMVD Stage C on conventional therapy were randomly assigned to placebo (n=7) and sildenafil (n=7) groups. On day 0, the recruited dogs underwent physical examinations, clinical score assessments, electrocardiography, systolic blood pressure measurements, blood collection, thoracic radiography, and echocardiography for baseline. The dogs then received a combination of conventional therapy with sildenafil or placebo every 8 h for 1 week. On day 7, all dogs underwent the baseline evaluations again.

Results:

The sildenafil group experienced a significant decrease in estimated systolic pulmonary artery pressure (sPAP) (p=0.043) from day 0 to day 7. Moreover, the total clinical scores were decreased in dogs treated with sildenafil relative to those who received the placebo (p=0.007); however, the lung scores were not different between before and after treatment with sildenafil.

Conclusion:

Sildenafil had a synergistic effect with conventional therapy in reducing the estimated sPAP and clinical scores in dogs with PH secondary to DMVD.

Antioxidant capacity of lipid- and water-soluble antioxidants in dogs with subclinical myxomatous mitral valve degeneration anaesthetised with propofol or sevoflurane

Background

Antioxidants located in both the hydrophilic and lipophilic compartments of plasma act as a defence system against reactive oxygen species (ROS). Excessive production of ROS during anaesthesia affects the antioxidant capacity of plasma and may result in oxidative stress. The aim of this study was to evaluate the antioxidant capacity of lipid- (ACL) and water-soluble (ACW) antioxidants in client-owned dogs diagnosed with periodontal disease and early-stage myxomatous mitral valve degeneration (MMVD) and anaesthetised for a dental procedure with propofol and sevoflurane or with propofol only.

Results

Dogs with MMVD were anaesthetised with propofol and sevoflurane (MMVD/PS, n = 8) or with propofol only (MMVD/P, n = 10). Dogs with no evidence of MMVD (PS, n = 12) were anaesthetised with propofol and sevoflurane. Blood samples for determination of ACL and ACW were collected before and 5 min, 60 min and 6 h after induction to anaesthesia. In MMVD/PS dogs, ACL was significantly higher at all sampling times when compared to PS dogs. Compared to basal values, only anaesthesia maintained with propofol significantly increased ACL at 60 min in dogs with MMVD. In MMVD/P dogs, ACW increased after induction to anaesthesia and remained elevated up to 6 h after anaesthesia. Compared to basal values, anaesthesia maintained with sevoflurane significantly increased ACW only at 60 min in both dogs with and without MMVD. The only difference between propofol and propofol/sevoflurane anaesthesia in dogs with MMVD was significantly higher ACW at 60 min after induction to anaesthesia in the propofol group.

Conclusions

Regarding antioxidant capacity, propofol could be a better choice than sevoflurane for anaesthesia of dogs with early-stage MMVD, although further studies are necessary to clarify the advantage of this antioxidant capacity.

Effect of temperature variation on hospital admissions and outcomes in dogs with myxomatous mitral valve disease and new onset pulmonary edema

The effect of seasonal variation on hospital admissions and outcomes in humans with cardiovascular disease and congestive heart failure (CHF) has been described. This study evaluates the effect of temperature variation on admissions and outcomes in dogs with myxomatous mitral valve disease (MMVD) and first onset CHF. Ninety-three client-owned dogs with MMVD and a first occurrence of pulmonary edema were included in this retrospective clinical cohort study. Recorded clinical and echocardiographic variables were accumulated and analyzed with dogs allocated into groups in a temperature-wise manner that considered the mean of the average (Tave) and maximum ambient temperature (Tmax) of the 14 days preceding hospital admission. A survival analysis was also performed. No difference was found in the percentage of dogs decompensating in three different temperature periods (i.e., cold, intermediate, and hot temperature) according to both Tave and Tmax. Dogs developing CHF during the intermediate temperatures according to Tmax died earlier from cardiac-related causes (median survival time 280 days, 95% CI = 147–486 days) compared to those decompensating during hot temperatures (median survival time 518 days, 95% CI = 344–819 days, P = 0.039). However, an effect of the ambient temperature on survival was not confirmed by Cox proportional hazard analysis. In conclusion, this study failed to show that ambient temperature has an effect on the first occurrence of CHF and outcomes in dogs with MMVD.

Dietary intervention reduces left atrial enlargement in dogs with early preclinical myxomatous mitral valve disease: a blinded randomized controlled study in 36 dogs

Background

Myxomatous mitral valve disease (MMVD), the most common naturally-occurring heart disease in dogs, is associated with alterations in energy metabolism, oxidative stress and inflammation. Energy deprivation plays a causal role in the development of heart failure. This study was designed to determine if a cardiac protection blend (CPB) of nutrients containing medium-chain triglycerides as an alternative energy source, fish oil to reduce inflammation, antioxidants, and other key nutrients important to cardiac health and function could slow or prevent MMVD progression. Nineteen dogs with early stage MMVD and 17 breed-, age-, and sex-matched healthy dogs were enrolled for a 6-month blinded, placebo-controlled study. Dogs in each cardiac health group were randomly assigned to either control diet (CON) or CPB-supplemented diet. Echocardiography was performed at baseline, 3 months and 6 months.

Results

No changes were found in healthy dogs. While MMVD-CON dogs had an average 10% increase over baseline in left atrial diameter (LAD) and left atrial to aortic root ratio (LA/Ao) at 6 months, MMVD-CPB dogs showed 3% decreases, resulting significant diet by time interactions (P = 0.037, P = 0.005, respectively). More MMVD-CON dogs progressed from stage B1 to B2 during the study. A positive correlation was found between 6-month changes in LAD and blood pressures in MMVD-CPB dogs (systolic: P = 0.050, diastolic: P = 0.035) but not MMVD-CON dogs.

Conclusions

Our results demonstrated efficacy of CPB-based dietary intervention in reducing LA size and mitral regurgitation, and in slowing or preventing the progression of early MMVD in dogs.

Survival of activated myofibroblasts in canine myxomatous mitral valve disease and the role of apoptosis

Myxomatous mitral valve disease (MMVD) is the single most important acquired cardiovascular disease of the dog. Much is known about the cellular changes and the contribution of activated myofibroblasts (valve interstitial cells (aVICs) to the valve extra-cellular matrix remodelling characteristic of the disease. However, little is known on how aVIC survival might contribute to disease pathogenesis. This study examined the temporal (disease severity-dependent) and spatial distribution of aVICs in MMVD valves, the expression of a range of apoptosis-related genes in cultured VICs from both normal (quiescent VIC (qVIC) and diseased (aVIC) valves, and the differential effects of doxorubicin treatment, as a trigger of apoptosis, on expression of the same genes. Activated myofibroblasts were identified in normal valves at the valve base only (the area closest to the annulus), and then became more numerous and apparent along the valve length as the disease progressed, with evidence of cell survival at the valve base. There were no significant differences in basal gene expression comparing qVICs and aVICs for CASP3, FAS, BID, BAX, BCL2, CASP8, DDIAS, XIAP and BIRC5. After doxorubicin treatment (2 mM) for 8 h there was significant difference (P < .05) in the expression of BID, BCL2, DDIAS, and CASP8, but when assessed for interactions using a mixed model ANOVA only CASP8 was significantly different because of treatment (P < .05). These data suggest aVIC survival in MMVD valves may be a consequence of heightened resistance of aVICs to apoptosis, but would require confirmation examining expression of the relevant proteins.

Left atrial anteroposterior diameter in dogs: reference interval, allometric scaling, and agreement with the left atrial-to-aortic root ratio

Left atrial enlargement (LAE) is a well-known negative prognostic factor in dogs with myxomatous mitral valve disease (MMVD). Left atrial-to-aortic root ratio (LA/Ao) is the most commonly used method to evaluate left atrial (LA) size in dogs, while the left atrial anteroposterior diameter (LAD) has been proposed as an additional measurement of LA size in different species. The aim of this study was to establish a normal reference range of LAD normalized to body weight (LADn) in dogs using allometric scales, and to evaluate the agreement between LADn and LA/Ao in the detection of LAE in dogs with MMVD. This was a retrospective, multicenter, observational study. We included 330 healthy dogs, 30 dogs with MMVD in ACVIM stage B1, 30 dogs in ACVIM stage B2, and 30 dogs in ACVIM stage C. The reference range for the LAD, depending on body weight, was between 16.91 mm and 49.68 mm. The reference range for the LADn in healthy dogs was between 10.49 and 15.72. LADn was significantly greater in dogs with MMVD compared to healthy dogs, and a significant difference in LADn was noted between different ACVIM stages (P<0.001). The most accurate cut-off value of LADn to differentiate between dogs in groups B2 and C was 20.3 (sensitivity, 83.3%; specificity, 83.3%). There was a misclassification rate of 37% between LADn and LA/Ao in the detection of LAE in group B1. This study provides a normal reference range for LAD in dogs, which can be used as an additional tool to assess LAE in dogs with MMVD.

ACVIM consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease in dogs

This report, issued by the ACVIM Specialty of Cardiology consensus panel, revises guidelines for the diagnosis and treatment of myxomatous mitral valve disease (MMVD, also known as endocardiosis and degenerative or chronic valvular heart disease) in dogs, originally published in 2009. Updates were made to diagnostic, as well as medical, surgical, and dietary treatment recommendations. The strength of these recommendations was based on both the quantity and quality of available evidence supporting diagnostic and therapeutic decisions. Management of MMVD before the onset of clinical signs of heart failure has changed substantially compared with the 2009 guidelines, and new strategies to diagnose and treat advanced heart failure and pulmonary hypertension are reviewed.

Factors associated with disease progression in dogs with presumed preclinical degenerative mitral valve disease attending primary care veterinary practices in the United Kingdom

BACKGROUND

Factors associated with disease progression in dogs with preclinical (stage B) degenerative mitral valve disease (DMVD) have not been evaluated previously in primary care veterinary practice.

OBJECTIVES

To evaluate whether plasma cardiac biomarkers, clinical signs, and physical examination findings are associated with clinical progression (reaching the composite endpoint of initiation of treatment with a potent diuretic or cardiac death) in dogs presumed to have stage B DMVD.

ANIMALS

Six-hundred and eighty-four dogs diagnosed with DMVD recruited from 73 primary care practices in the United Kingdom. Dogs were not receiving potent diuretics at recruitment.

METHODS

Prospective cohort study design. Primary care veterinarians recorded the presence or absence of clinical signs and physical examination findings. Baseline plasma N-terminal pro B-type natriuretic peptide (NT-proBNP) and cardiac troponin I were measured. Cox regression models measured associations between risk factor variables and clinical progression. Flexible parametric models generated predicted probabilities of reaching the composite endpoint for dogs with different combinations of prognostic risk factor variables.

RESULTS

Plasma NT-proBNP, heart rate, heart murmur intensity, presence of a cough, being a Cavalier King Charles Spaniel, and being prescribed pimobendan were associated with clinical progression to initiation of treatment with a potent diuretic or cardiac-related death.

CONCLUSIONS AND CLINICAL IMPORTANCE

Dogs with stage B DMVD identified as having a high risk of disease progression might benefit from more frequent monitoring or further diagnostic evaluation. The prognostic factors identified could facilitate risk stratification of dogs presenting with preclinical DMVD.

Assessment of plasma lactate and core-peripheral temperature gradient in association with stages of naturally occurring myxomatous mitral valve disease in dogs

OBJECTIVE

To evaluate plasma lactate concentrations and core-peripheral temperature gradients as perfusion parameters in dogs with heart failure caused by myxomatous mitral valve disease (MMVD) and to determine whether the above perfusion parameters are correlated with disease stages.

DESIGN

Prospective observational study.

SETTING

University teaching hospital.

ANIMALS

After excluding 129 dogs because of exclusion criteria, 7 dogs with heart failure classified as stage B2 and 10 dogs classified as stage C according to the American Heart Association (AHA)/American College of Cardiology (ACC) were included in the study. Six dogs without MMVD were evaluated as the control group.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Among the evaluated parameters, the plasma lactate concentrations were increased in stage C (median 3.70 mmol/L [33.3 mg/dL], interquartile range (IQR) 0.72 mmol/L [6.5 mg/dL]) compared with those in the control (median 2.80 mmol/L [25.2 mg/dL], IQR 0.8 mmol/L [7.2 mg/dL]; P = 0.024) and stage B2 groups (median 2.70 mmol/L [24.3 mg/dL], IQR 1.8 mmol/L [16.2 mg/dL]; P = 0.045). Significant differences were not observed in the core-peripheral temperature gradients among the control, stage B2, and stage C dogs.

CONCLUSIONS

Dogs with structural heart disease as a result of MMVD may have occult tissue hypoperfusion in stage C that is demonstrated by hyperlactatemia.

Rate of left ventricular pressure change by Doppler echocardiography in dogs with chronic mitral valve disease at different stages of congestive heart failure

Although the major pathological feature of chronic mitral valve disease is mitral regurgitation, myocardial dysfunction has been suggested to be present in dogs with chronic mitral valve disease. However, accurate assessment of myocardial function remains challenging. Doppler-derived rate of left ventricular pressure change is a simple, less load-dependent method for evaluating myocardial function. We aimed to evaluate Doppler-derived rate of left ventricular pressure change for assessing myocardial function in different stages of dogs with chronic mitral valve disease. This analytical cross-sectional study recruited 55 client-owned dogs with chronic mitral valve disease prospectively. Based on physical examination, indirectly measured blood pressure, routine hematologic and biochemistry examinations, thoracic radiography, electrocardiography, and echocardiography, dogs were diagnosed as mitral valve disease and excluded for systemic diseases and other cardiac diseases. They were classified according to the International Small Animal Cardiac Health Council scales. Doppler-derived rates of left ventricular pressure rise and fall (dP/dt and -dP/dt) were analyzed by two investigators using continuous-wave Doppler imaging. Doppler-derived dP/dt was higher in dogs of class III_a than in those of the other classes, whereas values of -dP/dt decreased significantly with the severity of congestive heart failure. The peak velocity of the early diastolic wave and -dP/dt were identified as independent predictors of congestive heart failure. Our findings suggested that Doppler-derived dP/dt and -dP/dt, used in combination with conventional echocardiographic variables, could allow a better understanding of myocardial dysfunction and a possibility for prediction of the risk of heart failure in dogs with chronic mitral valve disease.

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 findings and survival time in dogs with advanced heart failure

Background

Dogs with advanced heart failure are a clinical challenge for veterinarians but there are no studies reporting clinical features and outcome of this population.

Hypothesis/Objectives

To describe clinical findings and outcome of dogs with advanced heart failure caused by degenerative mitral valve disease (DMVD).

Animals

Fifty‐four dogs with advanced heart failure because of DMVD.

Methods

For study purposes, advanced heart failure was defined as recurrence of congestive heart failure signs despite receiving the initially prescribed dose of pimobendan, angiotensin‐converting‐enzyme inhibitor (ACEI), and furosemide >4 mg/kg/day. Data were collected for the time of diagnosis of Stage C heart failure and time of diagnosis of advanced heart failure. Date of death was recorded.

Results

At the diagnosis of advanced heart failure, doses of pimobendan (n = 30), furosemide (n = 28), ACEI (n = 13), and spironolactone (n = 4) were increased, with ≥1 new medications added in most dogs. After initial diagnosis of advanced heart failure, 38 (70%) dogs had additional medications adjustments (median = 2 [range, 0‐27]), with the final total medication number ranging from 2‐10 (median = 5). Median survival time after diagnosis of advanced heart failure was 281 days (range, 3‐885 days). Dogs receiving a furosemide dose >6.70 mg/kg/day had significantly longer median survival times (402 days [range, 3‐885 days] versus 129 days [range 9‐853 days]; P = .017).

Conclusions and Clinical Importance

Dogs with advanced heart failure can have relatively long survival times. Higher furosemide dose and non‐hospitalization were associated with longer survival.