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BackgroundA 5-year-old, healthy English Springer Spaniel died suddenly 4 months after delivering a litter of 7 puppies. Within 4 months of the dam's death, 3 offspring also died suddenly.HypothesisAbnormal cardiac repolarization, caused by an inherited long QT syndrome, is thought to be responsible for arrhythmias leading to sudden death in this family.AnimalsFour remaining dogs from the affected litter and 11 related dogs.MethodsPhysical examination and resting ECG were done on the littermates and 9 related dogs. Additional tests on some or all littermates included echocardiogram with Doppler, Holter monitoring, and routine serum biochemistry. Blood for DNA sequencing was obtained from all 15 dogs.ResultsThree of 4 littermates examined, but no other dogs, had prolonged QT intervals with unique T-wave morphology. DNA sequencing of the KCNQ1 gene identified a heterozygous single base pair mutation, unique to these 3 dogs, which changes a conserved amino acid from threonine to lysine and is predicted to change protein structure.Conclusions and clinical importanceThis family represents the first documentation in dogs of spontaneous familial QT prolongation, which was associated with a KCNQ1 gene mutation and sudden death. Although the final rhythm could not be documented in these dogs, their phenotypic manifestations of QT interval prolongation and abnormal ECG restitution suggested increased risk for sudden arrhythmic death. The KCNQ1 gene mutation identified is speculated to impair the cardiac repolarizing current IKs, similar to KCNQ1 mutations causing long QT syndrome 1 in humans.

Background: Activity of the circulating renin-angiotensin-aldosterone system (RAAS) has not been comprehensively characterized in cats with systemic hypertension (SH) or cardiomyopathy (CM), and the effects of furosemide or amlodipine treatment on the RAAS have not been fully evaluated in cats., Hypothesis/objectives: To document RAAS activity in cats with SH or CM compared to healthy cats and determine how RAAS profiles change with furosemide or amlodipine treatment., Animals: Sixty-six client-owned cats: 15 with SH (7 amlodipine-treated, 8 untreated), 17 with advanced CM (7 furosemide-treated, 10 not furosemide-treated), and 34 healthy cats., Methods: Equilibrium concentrations of RAAS peptides and aldosterone were quantified in serum samples by liquid chromatography-mass spectrometry. Variables were compared between groups using Kruskal-Wallis analysis with post hoc Holms-corrected Dunn's testing., Results: Compared with healthy cats, cats with CM had higher concentrations of angiotensin I, aldosterone, and plasma renin activity (all P < .01), and these differences remained significant (P < .03) after considering subgroups of untreated or furosemide-treated cats. Compared with healthy cats, untreated cats with SH showed no differences in RAAS biomarkers, whereas amlodipine-treated cats had higher concentrations of angiotensins I, II, III, IV, and 1-7, aldosterone, and plasma renin activity (all P < .03). Multivariable analysis determined that furosemide and amlodipine treatments were independent predictors of increased RAAS biomarker concentrations., Conclusions and Clinical Importance: Cats with CM had increased RAAS activity, whereas cats with untreated SH did not. Furosemide and amlodipine both led to nonspecific activation of both classical and alternative RAAS pathways in cats., (© 2022 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: Point-of-care lung ultrasound (LUS) is an effective tool to diagnose left-sided congestive heart failure (L-CHF) in dogs via detection of ultrasound artifacts (B-lines) caused by increased lung water., Hypothesis/objectives: To determine whether LUS can be used to monitor resolution of cardiogenic pulmonary edema in dogs, and to compare LUS to other indicators of L-CHF control., Animals: Twenty-five client-owned dogs hospitalized for treatment of first-onset L-CHF., Methods: Protocolized LUS, thoracic radiographs (TXR), and plasma N-terminal pro-B-type natriuretic peptide were performed at hospital admission, hospital discharge, and recheck examinations. Lung ultrasound findings were compared between timepoints and to other clinical measures of L-CHF., Results: From time of hospital admission to discharge (mean 19.6 hours), median number of LUS sites strongly positive for B-lines (>3 B-lines per site) decreased from 5 (range, 1-8) to 1 (range, 0-5; P < .001), and median total B-line score decreased from 37 (range, 6-74) to 5 (range, 0-32; P = .002). Lung ultrasound indices remained improved at first recheck (P < .001). Number of strong positive sites correlated positively with respiratory rate (r = 0.52, P = .008) and TXR edema score (r = 0.51, P = .009) at hospital admission. Patterns of edema resolution differed between LUS and TXR, with cranial quadrants showing more significant reduction in B-lines compared to TXR edema score (80% vs 29% reduction, respectively; P = .003)., Conclusions and Clinical Importance: Lung ultrasound could be a useful tool for monitoring resolution of pulmonary edema in dogs with L-CHF., (© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC. on behalf of the American College of Veterinary Internal Medicine.)

Background: Low vitamin D concentrations have been associated with advanced heart disease and poorer outcomes in people and dogs. Vitamin D status typically is assessed by serum 25(OH)D concentration. However, cats also produce notable amounts of a C-3 epimer of 25(OH)D (3-epi)., Hypothesis/objectives: Determine if vitamin D status, estimated by 25(OH)D 3 alone or combined with 3-epi (summation vitD), is lower in cats with cardiomyopathy (CM) compared to clinically normal (N) cats and if indicators of disease severity are associated with vitamin D status., Animals: Privately owned cats, 44 with CM and 56 N., Methods: Cross-sectional observational study using clinical and echocardiographic findings, diet history, and serum 25(OH)D 3 and 3-epi measurements., Results: Cat age was negatively related to vitamin D status. Summation vitD was lower in CM cats (median = 47.1 ng/mL) compared to N cats (median = 58.65 ng/mL) both before (P = .03) and after (P = .04) accounting for age. However, 25(OH)D 3 became nonsignificant between CM and N cats after age was included. Summation vitD was related positively to survival time and fractional shortening (FS), but negatively to left atrial enlargement (LAE) severity, both before and after accounting for age. For 25(OH)D 3 alone, only survival time and FS remained significant after including age., Conclusions and Clinical Importance: We report 25(OH)D 3 and 3-epi concentrations in CM and N cats. Age had an important (negative) relationship to vitamin D status. After accounting for age, summation vitD was lower in CM cats. Vitamin D status was related positively to survival time and FS, but negatively to LAE severity., (© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

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., (© 2019 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Background: The diagnosis of congestive heart failure (CHF) in cats is challenging. Point-of-care (POC) thoracic ultrasound and NT-proBNP testing are emerging tools that may aid in diagnosis., Hypothesis/objectives: To assess the diagnostic accuracy of POC lung ultrasound (LUS), focused cardiac ultrasound (FCU), and NT-proBNP in predicting a final diagnosis of CHF., Animals: Fifty-one cats in respiratory distress., Methods: Blood NT-proBNP, LUS, and FCU evaluating left atrial (LA) size and presence of pericardial effusion (PCEFF) were performed in all cats. Lung ultrasound findings including pleural effusion (PLEFF), number of B-lines, and sub-pleural abnormalities were noted. Medical records were evaluated for final diagnosis., Results: Thirty-three of 51 (65%) cats were diagnosed with CHF. Lung ultrasound and blood NT-proBNP were significant predictors of CHF in a multivariate model. The LUS criterion that maximized accuracy for CHF diagnosis was presence of >1 site strongly positive for B-lines (>3 B-lines per site), resulting in sensitivity of 78.8%, specificity of 83.3%, and area under the curve (AUC) of 0.833. Subjective LA enlargement was 97.0% sensitive and 100% specific for CHF (AUC 0.985). Presence of PCEFF also was 100% specific, but only 60.6% sensitive, for CHF (AUC 0.803). A positive blood NT-proBNP test was 93.9% sensitive and 72.2% specific for the diagnosis of CHF (AUC 0.831)., Conclusions and Clinical Importance: Point-of-care diagnostic techniques of LUS, FCU, and NT-proBNP are useful to diagnose CHF in cats with respiratory distress., (Copyright © 2018 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Background: Hypertrophic cardiomyopathy is the most prevalent heart disorder in cats and principal cause of cardiovascular morbidity and mortality. Yet, the impact of preclinical disease is unresolved., Hypothesis/objectives: Observational study to characterize cardiovascular morbidity and survival in cats with preclinical nonobstructive (HCM) and obstructive (HOCM) hypertrophic cardiomyopathy and in apparently healthy cats (AH)., Animals: One thousand seven hundred and thirty client-owned cats (430 preclinical HCM; 578 preclinical HOCM; 722 AH)., Methods: Retrospective multicenter, longitudinal, cohort study. Cats from 21 countries were followed through medical record review and owner or referring veterinarian interviews. Data were analyzed to compare long-term outcomes, incidence, and risk for congestive heart failure (CHF), arterial thromboembolism (ATE), and cardiovascular death., Results: During the study period, CHF, ATE, or both occurred in 30.5% and cardiovascular death in 27.9% of 1008 HCM/HOCM cats. Risk assessed at 1, 5, and 10 years after study entry was 7.0%/3.5%, 19.9%/9.7%, and 23.9%/11.3% for CHF/ATE, and 6.7%, 22.8%, and 28.3% for cardiovascular death, respectively. There were no statistically significant differences between HOCM compared with HCM for cardiovascular morbidity or mortality, time from diagnosis to development of morbidity, or cardiovascular survival. Cats that developed cardiovascular morbidity had short survival (mean ± standard deviation, 1.3 ± 1.7 years). Overall, prolonged longevity was recorded in a minority of preclinical HCM/HOCM cats with 10% reaching 9-15 years., Conclusions and Clinical Importance: Preclinical HCM/HOCM is a global health problem of cats that carries substantial risk for CHF, ATE, and cardiovascular death. This finding underscores the need to identify therapies and monitoring strategies that decrease morbidity and mortality., (Copyright © 2018 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

The purpose of this study was to assess the effects of systemic hypertension (SHT) on echocardiographic and radiographic cardiovascular variables in affected cats compared with healthy geriatric cats. Secondary objectives were to determine whether there were any relationships between these findings and age or systolic blood pressure (SBP). Fifteen healthy cats (>8 years of age with normal SBP) and 15 hypertensive cats (SBP > 180 mm Hg) were studied. Each cat was evaluated for standard echocardiographic parameters and 4 different aortic root dimensions. Seventeen variables were measured from right lateral and dorsoventral radiographic views. Left ventricle wall thickness was greater in the SHT group (5.1 +/- 0.9 mm) than in the healthy cats (4.2 +/- 0.5 mm). Left ventricular hypertrophy in the SHT cats often was not severe, and mean measures were considered normal. Some cats had asymmetrical septal hypertrophy (ASH) in the basilar portion of the septum as determined from the 2-dimensional view of the left ventricular outflow tract. ASH was greater in cats with SHT. Comparisons of the proximal ascending aorta indicated the presence of dilatation in the SHT cats, and comparison of the ascending aorta to the aortic annulus was helpful in differentiating between the 2 groups. The distal aortic root measurements and ratios evaluated by echocardiography were significantly different between the 2 groups of cats (P = .0001) and were significantly correlated with SBP (P = .0001) but not age (P > .3).

Twenty-four-hour ambulatory electrocardiograms were recorded in two age groups of 10 normal cats each: group 1 (1 to 4 years) and group 2 (8 to 14 years), with equal numbers of males and females in each group. Average heart rates over the 24-hour recording period ranged from 114 to 202 beats/minute (bpm). The mean 24-hour average rate did not differ between group 1 and group 2 (157.6 vs. 156.3+/-5.3 bpm, respectively); however, females (both groups combined) had higher average heart rates than males (166.8 vs. 147.1+/-5.3 bpm, respectively). Females also had a higher mean minimum heart rate than males (116.9 vs. 96.5+/-4.2 bpm, respectively); but there were no gender or age group differences in maximum heart rate. Results of hourly analyses of average, minimum, and maximum heart rates were similar. Mean heart rates rose from mid-afternoon to about 9:00 PM and were lowest just after midnight. Although regular sinus rhythm predominated, periods of sinus arrhythmia were evident in most cats, especially in early morning hours. Supraventricular extrasystoles were uncommon. Isolated ventricular extrasystoles occurred more frequently in group 2 cats; multiform configuration was observed in both groups. Repetitive ventricular extrasystoles, which usually consisted of occasional couplets, occurred more frequently in group 2 cats. One older cat had 2 short runs of ventricular tachycardia. Another older cat appeared to have a recurrent accelerated idioventricular rhythm.

A Veterinary Medical Database search from 1982 to 1995 identified 1,383 dogs with tumors of the heart from a total population of 729,265 dogs (0.19% incidence). Hemangiosarcoma (HSA) was the most common cardiac tumor identified. In the subset of dogs with specific histologic diagnoses, the number with HSA was almost 10-fold that of the 2nd most common tumor, aortic body tumor. Primary heart tumors were more common than cardiac metastases. When biologic behavior was noted, most heart tumors were classified as malignant. Cardiac tumors (excluding lymphoma) occurred most often in dogs between the ages of 7 and 15 years. In very old dogs (>15 years), the frequency of cardiac tumors was the same or lower than that of the youngest age group. Tumors occurred with similar frequency in males and females, but the relative risk for spayed females was >4 times that for intact females. For HSA, spayed females had >5 times greater relative risk than did intact females. The risk for castrated males was slightly greater than that for intact males, which had 2.4 times the relative risk of intact females. Thus, neutering appeared to increase the risk of cardiac tumor in both sexes. Intact females were least likely to develop a cardiac tumor, whereas spayed females were most likely to develop a tumor. Twelve breeds had greater than average risk of developing a cardiac tumor, whereas 17 had lower risk.

Mitral stenosis was diagnosed in 15 young to middle-aged dogs. There were 5 Newfoundlands and 4 bull terriers affected, suggesting a breed predisposition for this disorder. Clinical signs included cough, dyspnea, exercise intolerance, and syncope. Soft left apical diastolic murmurs were heard only in 4 dogs, whereas 8 dogs had systolic murmurs characteristic of mitral regurgitation. Left atrial enlargement was the most prominent radiographic feature. Left-sided congestive heart failure was detected by radiographs in 11 dogs within 1 year of diagnosis. Electrocardiographic abnormalities varied among dogs and included atrial and ventricular enlargement, as well as atrial and ventricular arrhythmias. Abnormalities on M-mode and two-dimensional echocardiograms included abnormal diastolic motion of the mitral valve characterized by decreased leaflet separation, valve doming, concordant motion of the parietal mitral valve leaflet, and a decreased E-to-F slope. Increased mitral valve inflow velocities and prolonged pressure half-times were detected by Doppler echocardiography. Cardiac catheterization, performed in 8 dogs, documented a diastolic pressure gradient between the left atrial, pulmonary capillary wedge, or pulmonary artery diastolic pressures and the left ventricular diastolic pressure. Necropsy showed mitral stenosis caused by thickened, fused mitral valve leaflets in 5 dogs and a supramitral ring in another dog. The outcome in affected dogs was poor; 9 of 15 dogs were euthanatized or died by 2 1/2 years of age.