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Introduction/objectives: Doppler echocardiographic estimation of transpulmonary pressure gradient (PG) is widely used to determine severity of pulmonary valve stenosis and indication for transcatheter intervention. The objective of this study was to describe agreement between Doppler echocardiographic methods of transpulmonary PG estimation and direct peak-to-peak pressure gradient at catheterization (PG cath ) in dogs. We hypothesized that with reference to PG cath , mean echocardiographic PG (PG echo-mean ) would have less bias than peak modal instantaneous echocardiographic PG (PG echo-peak )., Animals: Client-owned dogs with congenital pulmonary valve stenosis that underwent balloon pulmonary valvuloplasty at one of two veterinary teaching hospitals between June 2012 and May 2022 were included in this study., Materials and Methods: Cases that underwent transthoracic echocardiography and subsequent balloon pulmonary valvuloplasty separated by 30 or fewer days were retrospectively identified. For each echocardiogram, average PG echo-mean (mmHg) and average PG echo-peak (mmHg) were calculated from stored spectral Doppler recordings. Peak right ventricular-to-peak pulmonary artery PG data (mmHg) were obtained from catheterization reports. Bland-Altman analysis was used to assess agreement between echocardiographic and catheterization data., Results: Data from 209 dogs (n = 215 instances) were evaluated. Proportional bias, greater at higher gradients, was observed for PG echo-mean versus PG cath (P<0.001). A constant bias of -38.12 mmHg was observed for PG echo-peak versus PG cath (P=0.62). Bias for both echocardiographic variables had wide limits of agreement that increased with PG., Conclusions: Mean Doppler echocardiographic systolic transpulmonary pressure gradient and PG echo-peak underestimated and overestimated PG cath , respectively, preventing their interchangeability with PG cath ., Competing Interests: Conflicts of Interest Statement The authors do not have any conflicts of interest to disclose., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A 7-year-old male castrated Cavalier King Charles Spaniel was hospitalized for 12 days for treatment of severe congestive heart failure secondary to myxomatous mitral valve disease. During that time, 6 serum samples from different days were analyzed for serum biochemical and renin-angiotensin-aldosterone system components. Serum chloride concentrations (ranging from 71.6 to 103.1 mmol/L) were inversely related to angiotensin I concentrations, aldosterone concentrations, a surrogate marker of renin activity, and a surrogate marker of adrenal responsiveness to angiotensin II. In light of recent studies showing that hypochloremia is associated with advanced heart failure in dogs and is associated with poor outcomes in people, the information from the dog in this report supports exploration of RAAS dysregulation as an underlying mechanism., (© 2024 The Author(s). Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: Predicting progression of myxomatous mitral valve disease (MMVD) in dogs can be challenging., Hypothesis/objectives: The mitral regurgitation severity index (MRSI) will predict time to congestive heart failure (CHF) and all-cause death in dogs with MMVD., Animals: Eight hundred sixty-nine client-owned dogs., Methods: Retrospective study pooling data from 4 previous samples including dogs with MMVD stage B2 or C. MRSI was calculated as: (heart rate [HR]/120) × left atrium-to-aorta ratio (LA:Ao) × (age in years/10) × 100. Alternative MRSI formulas substituting radiographic measures of left atrial size were also calculated. Cox proportional hazard modeling and time-dependent receiver-operator characteristic curves quantified prognostic performance., Results: For Stage B2 pooled samples, MRSI > 156 was predictive of time to CHF (median 407 vs 1404 days; area under the curve [AUC] 0.68; hazard ratio 3.02 [95% CI 1.9-4.9]; P < .001). MRSI > 173 was predictive of all-cause death (median survival 868 vs 1843 days; AUC 0.64; hazard ratio 4.26 [95% CI 2.4-7.5]; P < .001). MRSI showed superior predictive value compared to the individual variables of HR, LA:Ao, and age. Variations of the MRSI equation substituting radiographic vertebral left atrial size for LA:Ao were also significantly predictive of outcome in stage B2. MRSI was not consistently predictive of outcome in Stage C., Conclusions and Clinical Importance: MRSI was predictive of outcome (onset of CHF and all-cause death) in MMVD Stage B2, demonstrating utility as a useful prognostic tool. Echocardiographic LA:Ao can be effectively replaced by radiographically determined LA size in the MRSI formula., (© 2023 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: Chronic renin-angiotensin-aldosterone system (RAAS) activation is harmful. Amlodipine activates RAAS in humans and dogs, but contradictory data exist for systemically hypertensive (SHT) cats., Hypothesis: Cats with SHT and chronic kidney disease treated with amlodipine (SHT/CKD-A) are RAAS activated., Animals: Client-owned cats: unmedicated normotensive (NT) cats ( n = 9); SHT/CKD-A cats ( n = 5) with median systolic blood pressure of 170 mmHg (vs. 195 mmHg, pre-treatment), chronic kidney disease, and receiving no RAAS-suppressive therapy., Methods: Serum was frozen (-80 °C) until RAAS analysis via equilibrium analysis. The RAAS variables (reported as median (minimum-maximum)) were compared between groups, using Mann-Whitney U test., Results: Angiotensin 1, angiotensin 1,7, angiotensin III, and angiotensin 1,5, and angiotensin-converting enzyme (ACE)-2 activity were higher in SHT/CKD-A cats compared to NT cats, while ACE activity was lower in SHT/CKD-A cats compared to NT cats ( p < 0.05 all). A marker for alternative RAAS influence (ALT-S) was significantly higher (69; 58-73 pmol/pmol) in SHT/CKD-A cats compared to NT cats (35; 14-63 pmol/pmol; p = 0.001). Aldosterone concentrations were significantly higher (393; 137-564 pmol/L) in SHT/CKD-A cats compared to NT cats (129; 28-206 pmol/L; p = 0.007)., Conclusion and Clinical Importance: Circulating RAAS is activated in systemically hypertensive cats receiving amlodipine. Although this study did not parse out the individual contributions of SHT, chronic kidney disease, and amlodipine, the findings suggest that the use of concurrent RAAS-suppressant therapy, specifically aldosterone antagonism, in amlodipine-treated SHT cats with chronic kidney disease might be indicated.

The role of taurine in the treatment of congestive heart failure (CHF) in dogs without systemic deficiency is unexplored. Taurine might have beneficial cardiac effects aside from deficit replacement. We hypothesized that oral taurine supplementation administered to dogs with naturally-occurring CHF would suppress the renin-angiotensin aldosterone system (RAAS). Oral taurine was administered to 14 dogs with stable CHF. Serum biochemical variables, blood taurine concentrations, and comprehensive analysis of RAAS variables were compared before and 2 weeks after taurine supplementation added to background furosemide and pimobendan therapy for CHF. Whole blood taurine concentrations increased after supplementation (median 408 nMol/mL, range 248-608 before and median 493 nMol/mL, range 396-690 after; P = .006). Aldosterone to angiotensin II ratio (AA2) was significantly decreased after taurine supplementation (median 1.00, range 0.03-7.05 before and median 0.65, range 0.01-3.63 after; P = .009), but no other RAAS components significantly differed between timepoints. A subset of dogs showed marked decreases in RAAS metabolites after supplementation and these dogs were more likely to have been recently hospitalized for CHF treatment than dogs that did not show marked decreases in classical RAAS metabolites. Overall, taurine only lowered AA2 in this group of dogs, however, response heterogeneity was noted, with some dogs showing RAAS suppression., (© 2023. The Author(s).)

Diuretics, such as furosemide, are routinely administered to dogs with congestive heart failure (CHF). Traditionally, dose and determination of efficacy primarily are based on clinical signs rather than quantitative measures of drug action. Treatment of human CHF patients increasingly is guided by quantification of urine sodium concentration (uNa) and urine volume after diuretic administration. Use of these and other measures of diuretic responsiveness is associated with decreased duration of hospitalization, complication rates, future rehospitalization, and mortality. At their core, loop diuretics act through natriuresis, and attention to body sodium (Na) stores and handling offers insight into the pathophysiology of CHF and pharmacology of diuretics beyond what is achievable from clinical signs alone. Human patients with low diuretic responsiveness or diuretic resistance are at risk for difficult or incomplete decongestion that requires diuretic intensification or other remedial strategies. Identification of the specific etiology of resistance in a patient can help tailor personalized interventions. In this review, we advance the concept of loop diuretic responsiveness by highlighting Na and natriuresis. Specifically, we review body water homeostasis and congestion in light of the increasingly recognized role of interstitial Na, propose definitions for diuretic responsiveness and resistance in veterinary subjects, review relevant findings of recent studies, explain how the particular cause of resistance can guide treatment, and identify current knowledge gaps. We believe that a quantitative approach to loop diuretic usage primarily involving natriuresis will advance our understanding and care of dogs with CHF., (© 2022 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: A recent study showed higher high-sensitivity cardiac troponin I (hs-cTnI) concentrations in healthy dogs eating grain-free (GF) compared to those eating grain-inclusive (GI) diets., Hypothesis/objectives: Healthy dogs with subclinical cardiac abnormalities eating GF diets at baseline will show improvements in cardiac biomarkers and echocardiographic variables after diet change, whereas healthy dogs eating GI diets at baseline will not improve., Animals: Twenty healthy dogs with subclinical cardiac abnormalities (12 Golden Retrievers, 5 Doberman Pinschers, 3 Miniature Schnauzers)., Methods: This prospective study included dogs with increased hs-cTnI or N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations, or echocardiographic abnormalities. Mixed modeling was used to evaluate echocardiographic, hs-cTnI, and NT-proBNP differences between groups (GF or GI diet at baseline) over time (1 y after diet change)., Results: Ten GF and 10 GI dogs were evaluated. There were statistically significant time: group interactions for hs-cTnI (P = .02) and normalized left ventricular internal systolic diameter (LVIDsN; P = .02), with GF dogs showing larger decreases in these variables than GI dogs. Median (range) hs-cTnI (ng/mL) for GF dogs was 0.141 (0.012-0.224) at baseline and 0.092 (0.044-0.137) at 1 y, and for GI dogs was 0.051 (0.016-0.195) at baseline and 0.060 (0.022-0.280) at 1 y. Median LVIDsN for GF dogs was 1.01 (0.70-1.30) at baseline and 0.87 (0.79-1.24) at 1 y, and for GI dogs was 1.05 (0.84-1.21) at baseline and 1.10 (0.85-1.28) at 1 y., Conclusions and Clinical Importance: Decreased hs-cTnI and LVIDsN in GF dogs after diet change supports reversibility of these subclinical myocardial abnormalities., (© 2022 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Introduction: Dilated cardiomyopathy (DCM) in dogs has been associated with feeding of grain-free (GF), legume-rich diets. Some dogs with presumed diet-associated DCM have shown improved myocardial function and clinical outcomes following a change in diet and standard medical therapy., Hypothesis: Prior GF (pGF) diet influences reverse cardiac remodeling and clinical outcomes in dogs with DCM and congestive heart failure (CHF)., Animals and Methods: A retrospective study was performed with 67 dogs with DCM and CHF for which diet history was known. Dogs were grouped by diet into pGF and grain-inclusive (GI) groups. Dogs in the pGF group were included if diet change was a component of therapy. Survival was analyzed using Kaplan-Meier curves and the Cox proportional-hazards model., Results: The median survival time was 344 days for pGF dogs vs. 253 days for GI dogs (P = 0.074). Statistically significant differences in median survival were identified when the analysis was limited to dogs surviving longer than one week (P = 0.033). Prior GF dogs had a significantly worse outcome the longer a GF diet was fed prior to diagnosis (P = 0.004) or if they were diagnosed at a younger age (P = 0.017). Prior GF dogs showed significantly greater improvement in normalized left ventricular internal diastolic diameter (P = 0.038) and E-point septal separation (P = 0.031) measurements and significant decreases in their furosemide (P = 0.009) and pimobendan (P < 0.005) dosages over time compared to GI dogs., Conclusions: Prior GF dogs that survived at least one week after diagnosis of DCM, treatment of CHF, and diet change had better clinical outcomes and showed reverse ventricular remodeling compared to GI dogs., Competing Interests: Conflict of interest statement Dr. Adin acknowledges research support from Nestle Purina PetCare. This financial support was not used directly for this study and did not influence its findings or conclusions. The remaining authors maintain no other conflicts of interest or financial gain from conducting this study., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: Recent studies have investigated dogs with presumed diet-associated dilated cardiomyopathy (daDCM), but prospective studies of multiple breeds are needed., Hypothesis/objectives: To evaluate baseline features and serial changes in echocardiography and cardiac biomarkers in dogs with DCM eating nontraditional diets (NTDs) or traditional diets (TDs), and in dogs with subclinical cardiac abnormalities (SCA) eating NTD., Animals: Sixty dogs with DCM (NTD, n = 51; TDs, n = 9) and 16 dogs with SCA eating NTDs., Methods: Echocardiography, electrocardiography, and measurement of taurine, cardiac troponin I, and N-terminal pro-B-type natriuretic peptide were performed in dogs with DCM or SCA. Diets were changed for all dogs, taurine was supplemented in most, and echocardiography and cardiac biomarkers were reassessed (3, 6, and 9 months)., Results: At enrollment, there were few differences between dogs with DCM eating NTDs or TDs; none had low plasma or whole blood taurine concentrations. Improvement in fractional shortening over time was significantly associated with previous consumption of a NTD, even after adjustment for other variables (P = .005). Median survival time for dogs with DCM was 611 days (range, 2-940 days) for the NTD group and 161 days (range, 12-669 days) for the TD group (P = .21). Sudden death was the most common cause of death in both diet groups. Dogs with SCA also had significant echocardiographic improvements over time., Conclusions and Clinical Importance: Dogs with DCM or SCA previously eating NTDs had small, yet significant improvements in echocardiographic parameters after diet changes., (© 2022 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)