Untargeted metabolomic profiling of dogs with myxomatous mitral valve disease and congestive heart failure shows metabolic differences associated with the presence of cardiac cachexia.

OBJECTIVE: To determine the effects of cardiac cachexia on the metabolomic profile in dogs with myxomatous mitral valve disease (MMVD). ANIMALS: 3 groups of dogs with MMVD enrolled between November 30, 2018, and April 7, 2022: (1) Dogs with congestive heart failure (CHF) and cachexia (CHF-cachexia group; n = 10); (2) dogs with CHF that had no cachexia (CHF-no cachexia group; n = 10); and (3) dogs with asymptomatic disease (American College of Veterinary Internal Medicine [ACVIM] Stage B2) with no cachexia (B2 group; n = 10). METHODS: Metabolomic profiles were analyzed from serum samples using ultra-high-performance liquid chromatography-tandem mass spectroscopy. Dogs in the 3 groups were compared, with statistical significance defined as P < .05 with a low false discovery rate (q < .10) and nominal statistical significance defined as P < .05 but q > .10. RESULTS: Numerous metabolites were significantly (n = 201) or nominally significantly (n = 345) different between groups. For example, when comparing the CHF-cachexia vs CHF-no cachexia groups, lipids were the predominant metabolite differences, including many medium- and long-chain dicarboxylates and dicarboxylate acylcarnitines. For comparisons of the CHF-cachexia vs B2 groups and the CHF-no cachexia vs B2 groups, amino acids, nucleotides, and cofactors/vitamins were the predominant metabolite differences. CLINICAL RELEVANCE: Some significant metabolite differences were identified between dogs with and without cardiac cachexia.

Comparison of echocardiography, biomarkers and taurine concentrations in cats eating high- or low-pulse diets.

OBJECTIVES: There are ongoing investigations into diet-associated dilated cardiomyopathy in dogs, but there has been minimal investigation into possible diet-associated dilated cardiomyopathy in cats. The objective of this study was to compare cardiac size and function, cardiac biomarkers and taurine concentrations in healthy cats eating high- vs low-pulse diets. We hypothesized that cats eating high-pulse diets would have larger hearts, lower systolic function and higher biomarker concentrations than cats eating low-pulse diets and that there would be no difference in taurine concentrations between the diet groups. METHODS: Echocardiographic measurements, cardiac biomarkers, and plasma and whole-blood taurine concentrations were compared between cats eating high- and low-pulse commercial dry diets in a cross-sectional study. RESULTS: There were no differences between the high- (n = 21) and low-pulse (n = 31) diet groups with regard to age, sex and breed, but more cats in the high-pulse group were overweight or obese (67% vs 39%; P = 0.05). Diet duration was not different in the groups, but the range was wide (6-120 months). No differences were found between the diet groups for key cardiac measurements, biomarker concentrations, or plasma or whole-blood taurine concentrations. However, there were significant negative correlations between diet duration and measures of left ventricular wall thickness in the high-pulse, but not the low-pulse, diet group. CONCLUSIONS AND RELEVANCE: This study did not detect significant associations between high-pulse diets and cardiac size, function and biomarkers, but the secondary observation of significant negative correlations between time on high-pulse diets and left ventricular wall thickness warrants further evaluation.

Echocardiographic, morphometric and biomarker changes in female cats followed from 6 to 24 months of life.

OBJECTIVES: The aim of the study was to evaluate cardiac size and early growth through echocardiographic, body weight (BW), body condition score (BCS), morphometric and biomarker changes in cats followed from 6 to 24 months of age. METHODS: Twenty-four female European shorthair colony cats were evaluated at birth for BW and at 6, 12, 18 and 24 months of age for BW, BCS, head length (HL) and head width (HW), N-terminal pro B-type natriuretic peptide (NT-proBNP), insulin-like growth factor-1 (IGF-1) and echocardiographic measurements. RESULTS: BCS, HW, left ventricular free wall in diastole, left atrium diameter and aortic diameter increased significantly between 6 and 12 months, while BW, HL and interventricular septum in diastole increased significantly between 6, 12 and 18 months, and BW decreased significantly between 18 and 24 months. NT-proBNP decreased significantly between 6 and 12 months. IGF-1 increased significantly between 6 and 12 months but decreased significantly between 12 and 18 months. CONCLUSIONS AND RELEVANCE: This study prospectively evaluated changes in echocardiographic measurements, BW, BCS, HL, HW, IGF-1 and NT-proBNP in cats during the first 2 years of life. Results show a comparable change over time for different variables. These findings contribute to the understanding of a possible relationship between cardiac measures and body size from young age through to adulthood.

Validation and preliminary data from a health-related quality of life questionnaire for owners of dogs with cardiac disease.

BACKGROUND: Cardiac disease in dogs impacts the quality of life (QoL) of their owners, but owners' QoL has not been comprehensively assessed in this population. OBJECTIVES: To develop, validate, and provide preliminary data from a health-related QoL (hrQoL) questionnaire for owners of dogs with cardiac disease. SUBJECTS: A total of 141 owners of dogs with cardiac disease were studied. METHODS: An owner hrQoL (O-hrQoL) questionnaire containing 20 items related to areas of a person's life that could be impacted by caring for a dog with cardiac disease was developed and administered to owners of dogs with cardiac disease. The highest possible total score was 100, with higher scores indicating a worse hrQoL. Readability, internal consistency, face and construct validity, and item-total correlations were assessed. RESULTS: Median O-hrQoL score was 35 (range, 0-87). The questionnaire had good internal consistency (Cronbach's α = 0.933), construct validity (Spearman's r = 0.38-0.53; Kendall's τ = 0.30-0.43; P < .001), and item-total correlation (Spearman's r = 0.44-0.79; Kendall's τ = 0.34-0.66; all P < .001). Fifty percent of owners indicated a negative effect of dogs' cardiac disease on their own QoL, but all owners responded that caring for their dogs either had strengthened (n = 76; 53.9%) or had no effect on their relationship with their dog (n = 65; 46.1%). CONCLUSIONS AND CLINICAL IMPORTANCE: The O-hrQoL questionnaire had good validity, and results suggest that owners' QoL is significantly impacted by caring for dogs with cardiac disease. Additional research on effective approaches to minimizing the negative effects of a dog's cardiac disease on the owner is warranted.

Extracellular vesicular microRNAs as potential biomarker for early detection of doxorubicin-induced cardiotoxicity.

BACKGROUND: Long-term use of doxorubicin (DOX) is limited by cumulative dose-dependent cardiotoxicity. OBJECTIVES: Identify plasma extracellular vesicle (EV)-associated microRNAs (miRNAs) as a biomarker for cardiotoxicity in dogs by correlating changes with cardiac troponin I (cTnI) concentrations and, echocardiographic and histologic findings. ANIMALS: Prospective study of 9 client-owned dogs diagnosed with sarcoma and receiving DOX single-agent chemotherapy (total of 5 DOX treatments). Dogs with clinically relevant metastatic disease, preexisting heart disease, or breeds predisposed to cardiomyopathy were excluded. METHODS: Serum concentration of cTnI was monitored before each treatment and 1 month after the treatment completion. Echocardiography was performed before treatments 1, 3, 5, and 1 month after completion. The EV-miRNA was isolated and sequenced before treatments 1 and 3, and 1 month after completion. RESULTS: Linear mixed model analysis for repeated measurements was used to evaluate the effect of DOX. The miR-107 (P = .03) and miR-146a (P = .02) were significantly downregulated whereas miR-502 (P = .02) was upregulated. Changes in miR-502 were significant before administration of the third chemotherapeutic dose. When stratifying miRNA expression for change in left ventricular ejection fraction, upregulation of miR-181d was noted (P = .01). Serum concentration of cTnI changed significantly but only 1 month after treatment completion, and concentrations correlated with left ventricular ejection fraction and left ventricular internal dimension in diastole. CONCLUSION AND CLINICAL SIGNIFICANCE: Downregulation of miR-502 was detected before significant changes in cTnI concentrations or echocardiographic parameters. Further validation using a larger sample size will be required.

Temporal changes in clinical and radiographic variables in dogs with preclinical myxomatous mitral valve disease: The EPIC study.

BACKGROUND: The Evaluation of pimobendan in dogs with cardiomegaly caused by preclinical myxomatous mitral valve disease (EPIC) study monitored dogs with myxomatous mitral valve disease (MMVD) as they developed congestive heart failure (CHF). OBJECTIVES: To describe the changes in clinical and radiographic variables occurring as dogs with MMVD and cardiomegaly develop CHF, compared to similar dogs that do not develop CHF. ANIMALS: One hundred and thirty-five, and 73 dogs that did or did not develop CHF, respectively. MATERIALS AND METHODS: The following variables were evaluated in 2 groups of dogs (dogs that did or did not develop CHF): Heart rate (HR), clinic respiratory rate (RR), home-measured resting respiratory rate (RRR), rectal temperature (RT), body weight (BW), and vertebral heart sum (VHS). Absolute value and rate of change of each variable were calculated for each day a dog was in study. Daily means were calculated and plotted against time. The onset of CHF or last visit before leaving the study were set as reference time points. RESULTS: The most extreme values and rate of change occurred in variables immediately before onset of CHF. Vertebral heart sum increased earliest. Heart rate, RR, and RRR also increased. Rectal temperature and BW decreased. Increases in RR and RRR were most extreme and occurred immediately before CHF. CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with MMVD and cardiomegaly experience increases in HR, RR, RRR, and VHS, and decreases in BW and RT as they develop CHF. The variables with highest absolute change and rate of change were RR and RRR. These findings reinforce the value of RR and RRR as indicators of impending or incipient CHF.

Cardiac cachexia in cats with congestive heart failure: Prevalence and clinical, laboratory, and survival findings.

BACKGROUND: Cardiac cachexia is common in people and dogs with congestive heart failure (CHF). However, the prevalence and effects of cardiac cachexia in cats are unknown. OBJECTIVES: To determine the prevalence of cachexia and its associations with clinical laboratory and survival data in cats with CHF. ANIMALS: One hundred twenty-five cats with CHF. METHODS: Medical records of cats evaluated during a 40-month period were retrospectively reviewed to identify cats with cardiac cachexia using 7 different definitions. Clinical, laboratory, and survival data were compared between cats with and without cachexia. RESULTS: Prevalence of cachexia ranged from 0 to 66.7% for the 7 definitions, with a prevalence of 41.6% using muscle condition score (MCS). Cats with cachexia (determined by MCS) were older (P < .001), more likely to have pleural effusion (P = .003), had significantly higher blood urea nitrogen (P < .001) and neutrophil concentrations (P = .01), and significantly lower body condition score (P < .001), body weights (P < .001), hematocrit (P = .007), and hemoglobin concentrations (P = .009). Survival time for cats with cachexia (determined by MCS) was significantly shorter than for cats without cachexia (P = .03). Cats that were underweight (P = .002) and cats with dilated cardiomyopathy (DCM) also had shorter survival times (P = .04). CONCLUSIONS AND CLINICAL IMPORTANCE: The association between cachexia and reduced survival time emphasizes the importance of identifying and addressing this common problem in cats with CHF.

Outcome and treatments of dogs with aortic thrombosis: 100 cases (1997-2014).

BACKGROUND: Aortic thrombosis (ATh) is an uncommon condition in dogs, with limited understanding of risks factors, outcomes, and treatments. OBJECTIVES/HYPOTHESIS: To describe potential risk factors, outcome, and treatments in dogs with ATh. ANIMALS: Client-owned dogs with a diagnosis of ATh based on ultrasonographic or gross necropsy examination. METHOD: Multicentric retrospective study from 2 academic institutions. RESULTS: One hundred dogs were identified. Anti-thrombin diagnosis, 35/100 dogs were nonambulatory. The dogs were classified as acute (n = 27), chronic (n = 72), or unknown (n = 1). Fifty-four dogs had at least one comorbidity thought to predispose to ATh, and 23 others had multiple comorbidities. The remaining 23 dogs with no obvious comorbidities were classified as cryptogenic. Concurrent illnesses potentially related to the development of ATh included protein-losing nephropathy (PLN) (n = 32), neoplasia (n = 22), exogenous corticosteroid administration (n = 16), endocrine disease (n = 13), and infection (n = 9). Dogs with PLN had lower antithrombin activity than those without PLN (64% and 82%, respectively) (P = .04). Sixty-five dogs were hospitalized with 41 subsequently discharged. Sixteen were treated as outpatient and 19 euthanized at admission. In-hospital treatments varied, but included thrombolytics (n = 12), alone or in combination with thrombectomy (n = 9). Fifty-seven dogs survived to discharge. Sixteen were alive at 180 days. Using regression analysis, ambulation status at the time of presentation was significantly correlated with survival-to-discharge (P < .001). CONCLUSIONS/CLINICAL IMPORTANCE: Dogs with ATh have a poor prognosis, with nonambulatory dogs at the time of presentation having worse outcome. Although the presence of comorbid conditions associated with hypercoagulability is common, an underlying cause for ATh was not always identified.

Long-term incidence and risk of noncardiovascular and all-cause mortality in apparently healthy cats and cats with preclinical hypertrophic cardiomyopathy.

BACKGROUND: Epidemiologic knowledge regarding noncardiovascular and all-cause mortality in apparently healthy cats (AH) and cats with preclinical hypertrophic cardiomyopathy (pHCM) is limited, hindering development of evidence-based healthcare guidelines. OBJECTIVES: To characterize/compare incidence rates, risk, and survival associated with noncardiovascular and all-cause mortality in AH and pHCM cats. ANIMALS: A total of 1730 client-owned cats (722 AH, 1008 pHCM) from 21 countries. METHODS: Retrospective, multicenter, longitudinal, cohort study. Long-term health data were extracted by medical record review and owner/referring veterinarian interviews. RESULTS: Noncardiovascular death occurred in 534 (30.9%) of 1730 cats observed up to 15.2 years. Proportion of noncardiovascular death did not differ significantly between cats that at study enrollment were AH or had pHCM (P = .48). Cancer, chronic kidney disease, and conditions characterized by chronic weight-loss-vomiting-diarrhea-anorexia were the most frequently recorded noncardiovascular causes of death. Incidence rates/risk of noncardiac death increased with age in AH and pHCM. All-cause death proportions were greater in pHCM than AH (65% versus 40%, respectively; P < .001) because of higher cardiovascular mortality in pHCM cats. Comparing AH with pHCM, median survival (study entry to noncardiovascular death) did not differ (AH, 9.8 years; pHCM, 8.6 years; P = .10), but all-cause survival was significantly shorter in pHCM (P = .0001). CONCLUSIONS AND CLINICAL IMPORTANCE: All-cause mortality was significantly greater in pHCM cats due to disease burden contributed by increased cardiovascular death superimposed upon noncardiovascular death.

Clinical and laboratory findings and survival time associated with cardiac cachexia in dogs with congestive heart failure.

BACKGROUND: Cardiac cachexia, loss of muscle mass associated with congestive heart failure (CHF), is associated with increased morbidity and shorter survival times in people, but an association between cardiac cachexia and survival has not been reported in dogs. OBJECTIVES: To determine the prevalence of cachexia and its associations with clinical, laboratory, and survival data in dogs with CHF. ANIMALS: Two hundred sixty-nine dogs with CHF. METHODS: Retrospective cohort study. Cachexia was defined by 1 of 2 definitions: (1) mild, moderate, or severe muscle loss or (2) weight loss of ≥5% in 12 months or less. Variables were compared between dogs with and without cachexia. RESULTS: One hundred thirty of 269 dogs (48.3%) had cardiac cachexia based on muscle loss, whereas 67 of 159 dogs (42.1%) with pre-evaluation body weights had cachexia based on weight loss. Dogs with cachexia (based on muscle loss) were significantly older (P = .05), more likely to have a cardiac arrhythmia (P = .02), had higher chloride concentrations (P = .04), and had a lower body condition score (P < .001), hematocrit (P = .006), hemoglobin (P = .006), and albumin (P = .004) concentrations. On multivariable analysis, cachexia (P = .05), clinically important tachyarrhythmias (P < .001), azotemia (P < .001), and being under- or overweight (both P = .003) were associated with shorter survival times. CONCLUSIONS AND CLINICAL IMPORTANCE: Cardiac cachexia in common in dogs with CHF and is associated with significantly shorter survival. This emphasizes the importance of preventing, diagnosing, and treating muscle loss in dogs with CHF.

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.

Clinical Features of English Bulldogs with Presumed Arrhythmogenic Right Ventricular Cardiomyopathy: 31 Cases (2001-2013).

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an important cause of sudden death in people and boxer dogs that has recently been described in English bulldogs. The objective of this retrospective study was to describe the clinical characteristics of English bulldogs with presumed ARVC. The medical records were searched for English bulldogs examined between 2001 and 2013 with a clinical diagnosis of ARVC. The average age of the 31 dogs identified was 9.2 ± 1.6 yr (range 7-13 yr). Males were overrepresented by a factor of 2.9 to 1. At initial presentation, 5 dogs had subclinical arrhythmia, 10 dogs had clinical signs attributable to arrhythmia, and 16 dogs had congestive heart failure. Eighteen dogs (58%) had ventricular tachycardia and five (16%) also had supraventricular arrhythmias. Four dogs experienced sudden death, 2 dogs died from congestive heart failure, 11 dogs were euthanized for cardiac causes, and 2 dogs died or were euthanized for noncardiac causes. Kaplan-Meier analysis showed a median survival time of 8.3 mo. This is the first study to describe the clinical characteristics of a population of English bulldogs with presumed ARVC. Further studies are needed to better characterize the clinical features of the disease in this breed.

Quantitative assessment of muscle in dogs using a vertebral epaxial muscle score.

Muscle loss associated with disease (cachexia) or with aging (sarcopenia) is common in dogs, but clinically relevant methods for quantifying muscle loss are needed. We previously validated an ultrasound method of quantifying muscle size in dogs in a single breed. The goal of this study was to assess the variability and reproducibility of the Vertebral Epaxial Muscle Score (VEMS) in other dog breeds. Static ultrasound images were obtained from 38 healthy, neutered dogs of 5 different breeds between 1- and 5-years-old. The maximal transverse right epaxial muscle height and area at the level of the 13th thoracic vertebra (T13) were measured. Length of the 4th thoracic vertebra (T4) was measured from thoracic radiography. Ratios of the muscle height and area to vertebral length (height/T4 and area/T4, respectively) were calculated to account for differences in body size among breeds. Reproducibility testing was performed on 2 dogs of each breed (26% of the total) to determine intra- and inter-investigator reproducibility, as well as intra-class correlation. Mean height/T4 = 1.02 ± 0.18 and mean area/T4 = 3.32 ± 1.68. There was no significant difference for height/T4 (P = 0.10) among breeds, but breeds were significantly different in area/T4 (P < 0.001). Intra-class correlation ranged from 0.80 to 0.99. Testing showed better reproducibility for height/T4 compared to area/T4. The VEMS using height/T4 was valid and reproducible for healthy dogs of different sizes and body conformations. Studies assessing this technique in dogs with congestive heart failure and other diseases associated with muscle loss are warranted.

La perte musculaire associée à la maladie (cachexie) ou à l'âge (sarcopénie) est fréquente chez les chiens, mais des méthodes appropriées pour quantifier en clinique la perte de muscle sont requises. Nous avons validé précédemment une méthode par échographie pour quantifier la taille musculaire chez des chiens d'une seule race. L'objectif de la présente étude était d'évaluer la variabilité et la reproductibilité du pointage du muscle épi-axial vertébral (PMEV) chez d'autres races de chien. Des images échographiques statiques furent obtenues de 38 chiens stérilisés en santé de cinq races différentes et âgés entre 1 et 5 ans. La hauteur transverse maximale du muscle épi-axial droit et la surface à la hauteur de la 13e vertèbre thoracique (T13) ont été mesurées. La longueur de la 4e vertèbre thoracique (T4) a été mesurée à partir de radiographies thoraciques. Les ratios de la hauteur du muscle et de la surface à la longueur de la vertèbre (hauteur/T4 et surface/T4, respectivement) ont été calculés pour tenir compte des différences de la taille entre les différentes races. Un test de reproductibilité a été effectué chez deux chiens de chaque race (26 % du total) afin de déterminer la reproductibilité intra- et inter-investigateur, ainsi que la corrélation intra-classe. La moyenne du ratio hauteur/T4 était de 1,02 ± 0,18 et la moyenne du ratio surface/T4 était de 3,32 ± 1,68. Il n'y avait pas de différence significative parmi les races pour le ratio hauteur/T4 (P = 0,10), mais les races différaient significativement pour ce qui est du ratio surface/T4 (P < 0,001). Les corrélations intra-classes variaient entre 0,80 et 0,99. Les tests ont montré une meilleure reproductibilité pour le ratio hauteur/T4 comparativement au ratio surface/T4. Le PMEV utilisant le ratio hauteur/T4 était valide et reproductible pour des chiens en santé de différentes tailles et conformations corporelles. Des études évaluant cette technique chez de chiens avec une défaillance cardiaque congestive et autres maladies associées avec de la perte musculaire sont justifiées. (Traduit par Docteur Serge Messier).

Vascular stent placement for palliation of mass-associated chylothorax in two dogs.

CASE DESCRIPTION 2 dogs with chylothorax were identified to have cardiac mass lesions obstructing the return of venous blood from the cranial vena cava. Chylous effusion was presumed to have been a result of an increase in cranial vena cava pressure affecting flow of chyle through the thoracic duct. CLINICAL FINDINGS Both dogs had tachypnea and pleural effusion requiring therapeutic thoracocentesis. Fluid analysis confirmed chylothorax. A heart-base mass was identified via echocardiography in each dog, and CT-angiographic findings confirmed obstruction to venous return in the cranial vena cava in both dogs and compression of the pulmonary artery in 1 dog. TREATMENT AND OUTCOME Each dog was anesthetized, and self-expanding endovascular stents were placed with fluoroscopic guidance. In both dogs, the site of stent placement was the cranial vena cava, and in 1 dog, an additional stent was positioned in the pulmonary artery. Chylous effusion resolved successfully in both dogs after surgery, with postoperative survival times exceeding 6 months. Complications included periprocedural arrhythmias in both dogs and eventual obstruction of the stent with tumor extension and fluid reaccumulation in 1 dog. CLINICAL RELEVANCE Endovascular stent placement may provide a useful palliative treatment for chylothorax secondary to vascular compression by a heart-base mass in dogs.

Acute tracheal compression in a large breed dog due to a dorsal tracheal membrane abscess.

OBJECTIVE: To describe a case of acute tracheal compression due to a dorsal tracheal membrane abscess in a dog. CASE SUMMARY: A 3-year-old intact male Bluetick Coonhound presented for evaluation of 36 hours of marked inspiratory dyspnea and stridor. A radiographic diagnosis of tracheal collapse was made on thoracic radiographs, which was confirmed to be static compression by tracheoscopy. Dorsal extraluminal tracheal compression from a fluid filled structure adjacent to the trachea was suspected based on ultrasonography. Endoscopic-guided transtracheal fine needle aspiration yielded septic suppurative inflammation. At surgery an abscess in the dorsal tracheal membrane was identified, lanced, and lavaged, which resulted in restoration of normal tracheal diameter. The dog developed bilateral pneumothorax, which was treated medically by thoracostomy tube placement and manual evacuation of the accumulated air. Postoperative radiographs also revealed evidence of pneumomediastinum. Pneumothorax and pneumomediastinum likely occurred secondary to the surgical approach, worsened by positive pressure ventilation. Cultures of the abscess isolated a nonhemolytic Streptococcus species but with no evidence of anaerobic bacteria. The dog made a full functional recovery. NEW OR UNIQUE INFORMATION PROVIDED: Tracheal compression is a rare diagnosis in dogs. To the authors' knowledge, this represents the first report of an abscess in the dorsal tracheal membrane, diagnosed by endoscopic-guided transtracheal fine needle aspiration, causing clinically relevant acute tracheal obstruction.

Pilot study of a myostatin antagonist in dogs with cardiac cachexia.

OBJECTIVES: Cardiac cachexia, a loss of lean body mass caused by heart disease, often accompanies congestive heart failure (CHF). Blocking myostatin, which is a protein that inhibits muscle growth, appears to greatly enhance muscle size and strength in rodent models and human clinical trials. The objective of this study was to evaluate a dog-specific myostatin antagonist (CAP-031) in a pilot study to test its safety and efficacy in dogs with CHF and cardiac cachexia. ANIMALS: Dogs with CHF and cardiac cachexia. METHODS: Eligible dogs received four weekly subcutaneous injections of CAP-031. Endpoints were body weight, body condition score (BCS, on a 1-9 scale), muscle condition score (MCS, on a five-point scale, where 0 = no muscle loss and 4 = severe muscle loss), appetite, and a quality of life (QOL) score. RESULTS: Seven dogs with CHF and moderate-to-severe cachexia were enrolled in the study. For the six dogs that completed the study, the median age was 8.8 years (range 6.4-10.6). At baseline, the median body weight was 27.0 kg (range 17.3-62.0), the median BCS was 4 (2-5), and median MCS was 3 (3-4). There were no significant changes in body weight, BCS, appetite, or QOL score. The change in MCS (from a median of 3 at baseline to a median of 2.5 at week 4) was not statistically significant (p = 0.06). CONCLUSIONS: The myostatin antagonist appeared to be well tolerated in most dogs. Earlier identification of cachexia is important, and randomized, controlled trials of myostatin antagonists or other drugs to treat cardiac cachexia are needed.

Expression Profiling of Circulating MicroRNAs in Canine Myxomatous Mitral Valve Disease.

MicroRNAs (miRNAs) are small non-coding RNAs that have shown promise as noninvasive biomarkers in cardiac disease. This study was undertaken to investigate the miRNA expression profile in dogs with myxomatous mitral valve disease (MMVD). 277 miRNAs were quantified using RT-qPCR from six normal dogs (American College of Veterinary Internal Medicine Stage A), six dogs with MMVD mild to moderate cardiac enlargement (ACVIM Stage B1/B2) and six dogs with MMVD and congestive heart failure (ACVIM Stage C/D). Eleven miRNAs were differentially expressed (False Discovery Rate < 0.05). Dogs in Stage B1/B2 or C/D had four upregulated miRNAs, including three cfa-let-7/cfa-miR-98 family members, while seven others were downregulated, compared to Stage A. Expression of six of the 11 miRNAs also were significantly different between dogs in Stage C/D and those in Stage B1/B2. The expression changes were greater as disease severity increased. These miRNAs may be candidates for novel biomarkers and may provide insights into genetic regulatory pathways in canine MMVD.

Combinatorial approach for large-scale identification of linked peptides from tandem mass spectrometry spectra.

The combination of chemical cross-linking and mass spectrometry has recently been shown to constitute a powerful tool for studying protein-protein interactions and elucidating the structure of large protein complexes. However, computational methods for interpreting the complex MS/MS spectra from linked peptides are still in their infancy, making the high-throughput application of this approach largely impractical. Because of the lack of large annotated datasets, most current approaches do not capture the specific fragmentation patterns of linked peptides and therefore are not optimal for the identification of cross-linked peptides. Here we propose a generic approach to address this problem and demonstrate it using disulfide-bridged peptide libraries to (i) efficiently generate large mass spectral reference data for linked peptides at a low cost and (ii) automatically train an algorithm that can efficiently and accurately identify linked peptides from MS/MS spectra. We show that using this approach we were able to identify thousands of MS/MS spectra from disulfide-bridged peptides through comparison with proteome-scale sequence databases and significantly improve the sensitivity of cross-linked peptide identification. This allowed us to identify 60% more direct pairwise interactions between the protein subunits in the 20S proteasome complex than existing tools on cross-linking studies of the proteasome complexes. The basic framework of this approach and the MS/MS reference dataset generated should be valuable resources for the future development of new tools for the identification of linked peptides.

Comparison of serum fatty acid concentrations in cats with hypertrophic cardiomyopathy and healthy controls.

n-3 fatty acids have some benefits in humans and dogs with cardiac disease, and plasma n-3 fatty acid concentrations have been shown to be decreased in dogs with congestive heart failure (CHF). However, there are no published studies reporting fatty acid concentrations in cats with cardiac disease. Therefore, the goal of this study was to compare serum fatty acid concentrations in normal cats and cats with hypertrophic cardiomyopathy (HCM), and determine if fatty acid concentrations correlate with left atrial size or the presence of CHF. Serum fatty acid concentrations were measured in normal cats and cats with HCM by gas chromatography. Twenty-three cats with HCM and 20 healthy controls were enrolled. Compared with healthy controls, cats with HCM had higher concentrations of palmitic acid (P = 0.01), docosahexanoic acid (DHA; P = 0.001) and total n-3 fatty acids (P = 0.03), and lower concentrations of linoleic acid (P = 0.03). Among cats with HCM, there were no differences in plasma fatty acid concentrations, and no association between left atrial dimension and fatty acid concentrations. Cats with HCM have some alterations in plasma fatty acids compared with healthy controls. Given the higher plasma concentrations of DHA, DHA supplementation is unlikely to have benefits in terms of correcting a deficiency; however, other effects of DHA or of supplementation of EPA warrant further investigation.

Phosphotyrosine signaling proteins that drive oncogenesis tend to be highly interconnected.

Mutation and overexpression of receptor tyrosine kinases or the proteins they regulate serve as oncogenic drivers in diverse cancers. To better understand receptor tyrosine kinase signaling and its link to oncogenesis, we used protein microarrays to systematically and quantitatively measure interactions between virtually every SH2 or PTB domain encoded in the human genome and all known sites of tyrosine phosphorylation on 40 receptor tyrosine kinases and on most of the SH2 and PTB domain-containing adaptor proteins. We found that adaptor proteins, like RTKs, have many high affinity bindings sites for other adaptor proteins. In addition, proteins that drive cancer, including both receptors and adaptor proteins, tend to be much more highly interconnected via networks of SH2 and PTB domain-mediated interactions than nononcogenic proteins. Our results suggest that network topological properties such as connectivity can be used to prioritize new drug targets in this well-studied family of signaling proteins.