Echocardiographic values for normal conditioned and unconditioned North American whippets.

BACKGROUND: Echocardiographic reference intervals have not been reported for North American whippets, or for whippets that have undergone pet-level athletic training. OBJECTIVES: To develop normal echocardiographic reference intervals for North American whippets and investigate differences in echocardiographic parameters based on athletic conditioning in pet whippets engaged in competitive sports. ANIMALS: One-hundred healthy North American whippets. METHODS: Dogs were examined at national shows between 2005 and 2009. Echocardiographic reference intervals were constructed and the effect of athletic conditioning on parameters of structure and function was assessed. RESULTS: Two dimensional, M-mode, Doppler and tissue Doppler reference ranges for healthy North American whippets are presented. Measures of left ventricular (LV) chamber diameter were larger in conditioned whippets (N = 25) and remained significantly larger than in unconditioned whippets (N = 16) when normalized for weight using allometric equations. Calculated LV mass was higher in conditioned dogs than in unconditioned dogs, and this difference persisted when LV mass was normalized by weight. Mitral E velocity was higher in conditioned dogs than in unconditioned dogs, whereas E/A and measures related to systolic function were not different. CONCLUSIONS AND CLINICAL IMPORTANCE: Pet whippets in peak athletic condition have larger hearts than do less conditioned whippets, but measures of systolic function are similar. Whippet pet athletes may show eccentric LV hypertrophy at peak condition. Normal values for cardiac size and function in North American whippets might be considered abnormal if population-specific whippet reference intervals are not used in analysis.

Use of radiographic measurements to diagnose stage B2 preclinical myxomatous mitral valve disease in dogs.

OBJECTIVE: To investigate the usefulness of radiographic measures of the left atrium and ventricle as surrogates for echocardiographic criteria in identifying dogs with stage B2 preclinical myxomatous mitral valve disease (MMVD). ANIMALS: 56 client-owned dogs with preclinical mitral regurgitation attributed to MMVD examined between April 19, 2016, and November 22, 2017. PROCEDURES: Medical records were retrospectively searched, and data collected included age, body weight, heart murmur grade, and echocardiographic and radiographic measurements. Dogs were grouped according to whether they did (case dogs) or did not (control dogs) meet echocardiographic criteria used to identify dogs with stage B2 MMVD. Measurements for lateral thoracic radiographic variables normalized to vertebral body units (VBUs) were obtained, and results were analyzed to identify variables that could best discriminate between case and control dogs. RESULTS: Three radiographic variables of left atrial size (vertebral left atrial size [VLAS], left atrial width, and the combined variable of VLAS + left atrial width) most accurately distinguished control dogs from case dogs, and the VLAS was the simplest and fastest to perform in a clinical setting. The optimal cutoff for VLAS was 2.5 VBUs (sensitivity, 70%; specificity, 84%; and likelihood ratio, 4.38), with VLAS ≥ 2.5 VBUs for case dogs. The maximum specificity cutoff for VLAS was 3.0 VBUs (sensitivity, 40%; specificity, 96%; and likelihood ratio, 10.0), with VLAS ≥ 3.0 VBUs for case dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that when echocardiography is unavailable, radiographic VLAS ≥ 3 VBUs could be used with minimal risk of false-positive diagnosis of stage B2 MMVD in dogs.

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.

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.

ACVIM consensus statement: Guidelines for the identification, evaluation, and management of systemic hypertension in dogs and cats.

An update to the 2007 American College of Veterinary Internal Medicine (ACVIM) consensus statement on the identification, evaluation, and management of systemic hypertension in dogs and cats was presented at the 2017 ACVIM Forum in National Harbor, MD. The updated consensus statement is presented here. The consensus statement aims to provide guidance on appropriate diagnosis and treatment of hypertension in dogs and cats.

International collaborative study to assess cardiovascular risk and evaluate long-term health in cats with preclinical hypertrophic cardiomyopathy and apparently healthy cats: The REVEAL Study.

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.

Echocardiographic effects of dexmedetomidine-ketamine in chinchillas ( Chinchilla lanigera).

Alpha2-agonist anesthetic combinations are often used in rodent anesthesia but no information about their effects on cardiac function in chinchillas exists. The purpose of this study was to utilize echocardiography to evaluate the cardiovascular effects of dexmedetomidine-ketamine anesthesia in chinchillas. Echocardiographic examinations were performed in eight adult chinchillas under manual restraint and following dexmedetomidine (0.015 mg/kg) and ketamine (4 mg/kg) administration. Dexmedetomidine-ketamine anesthesia resulted in a significantly decreased heart rate, fractional shortening, cardiac output, and flow velocity across the aortic and pulmonic valves, and significantly increased left ventricular internal diameter in systole. The observed changes in echocardiographic parameters are similar to those previously reported in chinchillas anesthetized with isoflurane.

Severity of Mitral Valve Degeneration Is Associated with Chromosome 15 Loci in Whippet Dogs.

Mitral valve degeneration (MVD) is the most common form of heart disease in dogs, frequently leading to left-sided congestive heart failure and cardiac mortality. Although breed-specific disease characteristics and overrepresentation point towards a genetic origin for MVD, a causative mutation and complete molecular pathogenesis are unknown. Whippet dogs are overrepresented in incidence of MVD, suggesting an inherited component in this breed. Expressivity of this condition is variable with some dogs showing evidence of more severe disease at earlier ages than other dogs. This phenomenon makes a traditional case versus control genetic study prone to phenotyping error. This study sought to avoid these common pitfalls by identifying genetic loci associated with severity of MVD in Whippets through a genome-wide association study (GWAS). 138 Whippet dogs were characterized for MVD by echocardiographic examination and a novel disease severity score was developed and adjusted for age in each subject. Single nucleotide polymorphism (SNP) genotype data (170k Illumina CanineHD SnpChip) was obtained for DNA isolated from blood of each study subject. Continuous variable genome wide association was performed after correction for population stratification by efficient mixed model association expedited (EMMAX) in 130 dogs. A genome wide significant association was identified on chromosome 15 (peak locus 57,770,326; Padj = 0.049) and secondary loci of suggestive association were identified on chromosome 2 (peak locus 37,628,875; Padj = 0.079). Positional candidate genes were identified within the primary and secondary loci including follistatin-related protein 5 precursor (FSTL5) and Rho GTPase-activating protein 26 (ARHGAP26). These results support the hypothesis that severity of MVD in whippets has a genetic basis and warrants further study by either candidate gene sequencing or next-generation techniques.

QUANTITATIVE PLANAR AND VOLUMETRIC CARDIAC MEASUREMENTS USING 64 MDCT AND 3T MRI VS. STANDARD 2D AND M-MODE ECHOCARDIOGRAPHY: DOES ANESTHETIC PROTOCOL MATTER?

Cross-sectional imaging of the heart utilizing computed tomography and magnetic resonance imaging (MRI) has been shown to be superior for the evaluation of cardiac morphology and systolic function in humans compared to echocardiography. The purpose of this prospective study was to test the effects of two different anesthetic protocols on cardiac measurements in 10 healthy beagle dogs using 64-multidetector row computed tomographic angiography (64-MDCTA), 3T magnetic resonance (MRI) and standard awake echocardiography. Both anesthetic protocols used propofol for induction and isoflourane for anesthetic maintenance. In addition, protocol A used midazolam/fentanyl and protocol B used dexmedetomedine as premedication and constant rate infusion during the procedure. Significant elevations in systolic and mean blood pressure were present when using protocol B. There was overall good agreement between the variables of cardiac size and systolic function generated from the MDCTA and MRI exams and no significant difference was found when comparing the variables acquired using either anesthetic protocol within each modality. Systolic function variables generated using 64-MDCTA and 3T MRI were only able to predict the left ventricular end diastolic volume as measured during awake echocardiogram when using protocol B and 64-MDCTA. For all other systolic function variables, prediction of awake echocardiographic results was not possible (P = 1). Planar variables acquired using MDCTA or MRI did not allow prediction of the corresponding measurements generated using echocardiography in the awake patients (P = 1). Future studies are needed to validate this approach in a more varied population and clinically affected dogs.

Aortic tear and dissection related to connective tissues abnormalities resembling Marfan syndrome in a Great Dane.

Aortic tears and acute aortic dissection are rarely reported in dogs. This report describes a case of aortic dissection and probable sinus of Valsalva rupture in a young Great Dane with associated histopathologic findings suggestive of a connective tissue abnormality.

Accuracy of Doppler echocardiographic estimates of pulmonary artery pressures in a canine model of pulmonary hypertension.

OBJECTIVES: To compare noninvasive estimates of pulmonary artery pressure (PAP) obtained via echocardiography (ECHO) to invasive measurements of PAP obtained during right heart catheterization (RHC) across a range of PAP. To examine the accuracy of estimating right atrial pressure via ECHO (RAPECHO) compared to RAP measured by RHC (RAPRHC), and determine if adding RAPECHO improves the accuracy of noninvasive PAP estimations. ANIMALS: 14 healthy female beagle dogs. METHODS: Comparison of ECHO and RHC measures of PAP, both at normal PAP and increased PAP generated by microbead embolization. RESULTS: Noninvasive estimates of PAP were moderately but significantly correlated (r of 0.68-0.78; p < 0.0006) with invasive measurements of PAP. Wide variance was noted for all estimations, with increased variance at higher PAP. The addition of RAPECHO improved correlation and bias in all cases. RAPRHC was significantly correlated with RAPECHO (r = 0.38; p = 0.04) as estimated by the ellipse area method. Median RAPRHC was significantly different between 3 subjective assessments of right atrial size (p = 0.037). CONCLUSIONS: Spectral Doppler assessments of tricuspid and pulmonic regurgitation are imperfect methods for predicting PAP as measured by catheterization despite an overall moderate correlation between invasive and noninvasive values. Noninvasive measurements may be better utilized as part of a comprehensive assessment of PAP in canine patients. RAPRHC appears best estimated based on subjective assessment of RA size. Including estimated RAPECHO in estimates of PAP improves the correlation and relatedness between noninvasive and invasive measures of PAP, but notable variability in accuracy of estimations persists.

Effects of two different anesthetic protocols on cardiac flow measured by two dimensional phase contrast magnetic resonance imaging.

Companion animals are routinely anesthetized or heavily sedated for cardiac MRI studies, however effects of varying anesthetic protocols on cardiac function measurements are incompletely understood. The purpose of this prospective study was to compare effects of two anesthetic protocols (Protocol A: Midazolam, fentanyl; Protocol B: Dexmedetomidine) on quantitative and qualitative blood flow values measured through the aortic, pulmonic, mitral, and tricuspid valves using two-dimensional phase contrast magnetic resonance imaging (2D PC MRI) in healthy dogs. Mean flow per heartbeat values through the pulmonary artery (Qp) and aorta (Qs) were compared to right and left ventricular stroke volumes (RVSV, LVSV) measured using a reference standard of 2D Cine balanced steady-state free precession MRI. Pulmonary to systemic flow ratio (Qp/Qs) was also calculated. Differences in flow and Qp/Qs values generated using 2D PC MRI did not differ between the two anesthetic protocols (P = 1). Mean differences between Qp and RVSV were 3.82 ml/beat (95% limits of agreement: 3.62, -11.26) and 1.9 ml/beat (-7.86, 11.66) for anesthesia protocols A and B, respectively. Mean differences between Qs and LVSV were 1.65 ml/beat (-5.04, 8.34) and 0.03 ml/beat (-4.65, 4.72) for anesthesia protocols A and B, respectively. Mild tricuspid or mitral reflux was seen in 2/10 dogs using 2D PC MRI. No aortic or pulmonic insufficiency was observed. Findings from the current study indicated that these two anesthetic protocols yield similar functional measures of cardiac blood flow using 2D PC MRI in healthy dogs. Future studies in clinically affected patients are needed.

Multi-centered investigation of a point-of-care NT-proBNP ELISA assay to detect moderate to severe occult (pre-clinical) feline heart disease in cats referred for cardiac evaluation.

OBJECTIVE: To prospectively evaluate the diagnostic accuracy of a point-of-care (POC) N-terminal pro-B-type natriuretic peptide (NT-proBNP) ELISA to assess the likelihood of moderate to severe occult heart disease (OcHD) in a clinical population of cats suspected to have heart disease. ANIMALS: One hundred and forty-six asymptomatic client-owned cats with a heart murmur, gallop rhythm, arrhythmia, or cardiomegaly. METHODS: Physical examination, blood pressure measurement and echocardiography were performed prospectively. Point-of-care ELISA was visually assessed as either positive or negative by a reader blinded to the echocardiographic results. RESULTS: Forty-three healthy cats, 50 mild OcHD, 31 moderate OcHD, 6 severe OcHD, and 16 cats equivocal for OcHD were examined. Cats with OcHD included 65 with hypertrophic cardiomyopathy, 6 with restrictive or unclassified cardiomyopathy, 1 with arrhythmogenic right ventricular cardiomyopathy, and 15 with non-cardiomyopathic forms of heart disease. Point-of-care ELISA differentiated cats with moderate or severe OcHD with sensitivity/specificity of 83.8%/82.6% and overall accuracy of 82.9%. Positive POC ELISA increased likelihood of moderate or severe OcHD by a factor of 4.8 vs. those that tested negative. Point-of-care ELISA differentiated cats with moderate or severe cardiomyopathic OcHD with sensitivity/specificity of 88.6%/81.3% and overall accuracy of 83.2%. CONCLUSION: In a select sample of cats referred for cardiac evaluation, positive POC NT-proBNP ELISA increases likelihood of moderate to severe OcHD while negative POC NT-proBNP ELISA result excludes moderate to severe OcHD.

Systemic hypertension and hypertensive retinopathy following PPA overdose in a dog.

A 4 yr old spayed female Labrador retriever was examined 4 hr after ingesting an overdose of phenylpropanolamine (PPA). Clinical signs included anxiety, piloerection, mucosal ulceration, cardiac arrhythmia, mydriasis, and hyphema. Clinicopathologic abnormalities included elevated creatine kinase (CK) and aspartate aminotransferase (AST), proteinuria, and pigmenturia. Ventricular tachycardia and severe systemic hypertension were documented. Hyphema and retinal detachment were documented oculus uterque (OU). Phenoxybenzamine, sotalol, and esmolol resolved the ventricular tachycardia, and blood pressure was controlled with nitroprusside. All clinicopathologic and cardiac abnormalities resolved within 7 days, and ocular changes resolved within 1 mo. Monitoring of blood pressure and rapid pharmacologic intervention were successful in controlling hypertension secondary to PPA overdose and minimizing retinal damage.

Pulmonary hypertension in canine degenerative mitral valve disease.

Pulmonary hypertension secondary to degenerative mitral valve disease has been recognized clinically for many years in veterinary medicine, and clinical diagnosis of this syndrome in dogs has been enhanced greatly by widespread use of echocardiography and Doppler echocardiography. Medical therapy is now available to treat this clinical complication of mitral valve disease, making timely diagnosis even more important to patient longevity and quality of life.

Prediction of first onset of congestive heart failure in dogs with degenerative mitral valve disease: the PREDICT cohort study.

OBJECTIVE: To identify risk factors for first-onset congestive heart failure (CHF) in dogs with degenerative mitral valve disease (DMVD). ANIMALS: Eighty-two dogs with and without CHF secondary to DMVD were retrospectively assigned to a derivation cohort. Sixty-five dogs with asymptomatic DMVD were recruited into a prospective validation cohort. METHODS: Variables associated with risk of CHF in dogs were identified in a derivation cohort and used to construct a predictive model, which was then prospectively tested through longitudinal examination of a validation cohort. RESULTS: Logistic regression analysis of the derivation cohort yielded a predictive model that included the left atrial to aortic root dimension ratio (LA:Ao) and plasma concentration of N-terminal pro-B-type natriuretic peptide (NT-proBNP). When this model was prospectively applied to the validation cohort, it correctly predicted first-onset of CHF in 69.2% of cases. Analysis of the validation cohort revealed that plasma NT-proBNP concentration and indexed left ventricular end-diastolic diameter (LVIDd:Ao) were independent risk factors for development of first-onset CHF in dogs with DMVD (NT-proBNP ≥ 1500 pmol/L, odds ratio (OR), 5.76, 95% confidence interval (CI), 1.37-24.28, P = 0.017; LVIDd:Ao ≥ 3, OR, 6.11, 95% CI, 1.09-34.05, P = 0.039). CONCLUSIONS: Measures of left heart size and plasma NT-proBNP concentration independently estimate risk of first-onset of CHF in dogs with DMVD. These parameters can contribute to the management of dogs with DMVD.

NT-proBNP, NT-proANP and cTnI concentrations in dogs with pre-capillary pulmonary hypertension.

OBJECTIVES: To compare [NT-proBNP], [NT-proANP] and [cTnI] between control dogs with respiratory disease without pulmonary hypertension (PH) and dogs with pre-capillary PH, and to assess the accuracy of [NT-proBNP], [NT-proANP], [cTnI] to predict Doppler-derived peak tricuspid regurgitation (TR) gradient. ANIMALS: 20 dogs. 8 control dogs with respiratory disease with no PH and 12 with pre-capillary PH. METHODS: [NT-proBNP], [NT-proANP] and [cTnI] were compared between the 2 groups and simple linear regression analysis was used to predict peak TR gradients from various blood biomarkers. RESULTS: Median [NT-proBNP] was higher in the dogs with PH (2011 pmol/L, 274-7713 pmol/L) compared to control dogs (744 pmol/L; 531-2710 pmol/L) (p = 0.0339). [NT-proBNP] was associated with peak TR gradient (R(2) = 0.7851, p = 0.0001). Median [NT-proANP] did not differ between dogs with PH (1747 fmol/L; 894-2884 fmol/L) and control dogs (1209 fmol/L; 976-1389 fmol/L (p = 0.058). [NT-proANP] was not associated with peak TR gradient (R(2) = 0.2780, p = 0.0781). Median [cTnI] did not differ between dogs with PH (0.2850 ng/mL; 0.19-1.13 ng/mL) and control dogs (0.2 ng/mL; 0.19-0.82 ng/mL, p = 0.3051). Median [TnI] was not associated with peak TR gradient (R(2) = 0.024, p = 0.6307). CONCLUSIONS: [NT-proBNP] concentration is significantly higher in dogs with pre-capillary PH when compared to dogs with respiratory disease without PH, and [NT-proBNP] may be useful to predict the severity of estimated PH. Elevations in [NT-proBNP] due to pre-capillary PH may complicate the interpretation of [NT-proBNP] elevations in patients presenting with cardiorespiratory abnormalities. [NT-proANP] and [cTnI] were not elevated in dogs with pre-capillary PH.