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Three cats were presented for unusual collapsing episodes. Echocardiography revealed a hypertrophic cardiomyopathy (HCM) phenotype in each cat. Continuous electrocardiographic monitoring showed that the clinical signs coincided with periods of severe ST-segment elevation in each cat. The first cat was treated with amlodipine and diltiazem but did not improve and was euthanized due to poor quality of life. Postmortem examination revealed cardiac lymphoma without obstructive coronary disease. The second cat was thought to have cardiac lymphoma, based on pericardial effusion cytology, and was euthanized before starting therapy. The third cat was diagnosed with HCM and left ventricular outflow tract obstruction and was treated with atenolol and diltiazem. This treatment reduced the frequency of episodic clinical signs, but the cat subsequently developed congestive heart failure and was euthanized. This case series describes clinical signs associated with severe ST elevation in cats with an HCM phenotype, and their outcomes. Continuous electrocardiographic monitoring was necessary to detect transient ST elevation in each case. [ABSTRACT FROM AUTHOR]

Objectives To describe the outcome for nine dogs with pulmonic stenosis treated by open patch grafting using expanded polytetrafluoroethylene under cardiopulmonary bypass. Materials and Methods Data were collected from the hospital records of all dogs that had undergone right ventricular outflow tract grafting with an expanded polytetrafluoroethylene patch under cardiopulmonary bypass between 2006 and 2012 for the treatment of pulmonic stenosis. Echocardiographic images were reviewed and the pressure gradient across the right ventricular outflow tract re-measured. Owners of dogs still alive at the time of writing were invited to return to the hospital for reassessment. Results Nine dogs met the inclusion criteria. Median pressure gradient preoperatively was 118 mmHg, (range 102 to 259 mmHg) reducing to a median of 20 mmHg (range 7 to 53 mmHg) at 48 hours postoperatively and 14 mmHg (range 10 to 70 mmHg), with a median percentage reduction of 89% (range 41 to 94%) at long-term follow-up. Eight of nine dogs survived surgery, with six of nine surviving to hospital discharge. Two dogs were still alive over 6 and 8 years postoperatively. No long-term deaths were believed to be attributable to pulmonic stenosis. Clinical Significance Expanded polytetrafluoroethylene patch grafting of the right ventricular outflow tract for treatment of severe pulmonic stenosis in dogs is feasible and can be an effective method to reduce the severity of right ventricular outflow tract obstruction. [ABSTRACT FROM AUTHOR]

Background: Cats with hypertrophic cardiomyopathy (HCM) and congestive heart failure (CHF) can have resolution of both left ventricular hypertrophy and CHF. Objectives: To describe the clinical characteristics of cats with transient myocardial thickening (TMT) and CHF compared with a control population of cats without resolution of HCM. Animals: A total of 21 cats with TMT, 21 cats with HCM. Methods: Retrospective study. Clinical records at 4 veterinary centers were searched for TMT cases and a control group of cats with HCM and CHF. TMT was defined as initial maximal left ventricular wall thickness (LVWT) ≥6 mm with left‐sided CHF, with subsequent resolution of CHF, reduction in left atrium/aorta (LA/Ao), and LVWT<5.5 mm. HCM was defined as persistent LVWT ≥6 mm. Results: Cats with TMT were younger (2 [0.4–11.4] years) than cats with HCM (8 [1.6–14] years) (P < 0.0001), and antecedent events were more common (15/21 versus 6/21, respectively) (P = 0.01). In cats with TMT, LVWT normalized from 6.8 [6.0–9.7] mm to 4.8 [2.8–5.3] mm and LA/Ao decreased from 1.8 [1.6–2.3] to 1.45 [1.2–1.7] after a mean interval of 3.3 (95% CI: 1.8–4.7) months. CHF recurred in 1 of 21 TMT and 15 of 21 cats with HCM. Cardiac treatment was discontinued in 20 of 21 cats with TMT and 0 of 21 HCM cats. All cats with TMT survived, whereas 8 of 19 cats with HCM died during the study period. Conclusions and Clinical Importance: TMT occurs in younger cats, and antecedent events are common. The prognosis is better in cats with CHF associated with TMT than HCM. [ABSTRACT FROM AUTHOR]

Background Mean systolic blood pressure in apparently healthy cats has been reported as approximately 125 mmHg using direct assessment, but there is greater variability in reported values using indirect assessment. Increasing age and the white-coat effect are associated with increased systolic blood pressure. Hypothesis/Objectives To report Doppler-derived blood pressure measurements from a large population of apparently healthy cats and to assess epidemiologic factors associated with recorded blood pressures. Animals A total of 780 cats in rehoming centers enrolled in a screening program for heart murmurs and cardiac disease. Methods Cats were considered healthy based on history and physical examination. Cats with known hypertension, hyperthyroidism, or clinical signs of systemic disease and pregnant or nursing queens were excluded. After an acclimatization period, systolic blood pressure was measured using the Doppler sphygmomanometry method following the recommendations of the ACVIM Consensus Statement. General linear model analysis was performed to identify factors associated with variation in systolic blood pressure. Results Median (interquartile range, IQR) systolic blood pressure for the group was 120.6 (110.4-132.4) mmHg. Factors significantly associated with higher systolic blood pressure in a general linear model were increased age, increased nervousness, male sex, neutering, or history of being a stray. The model explained 29.2% of the variation in systolic blood pressure. Conclusions and Clinical Importance The age, demeanor, sex, neuter status and history of being a stray should be taken into account when assessing systolic blood pressure in apparently healthy cats. [ABSTRACT FROM AUTHOR]

Background Cardiovascular disease is associated with endothelial dysfunction in humans and studies of plasma biomarkers suggest that dogs with myxomatous mitral valve disease ( MMVD) might also have endothelial dysfunction. Hypothesis That progression of mitral regurgitation ( MR) is associated with development of endothelial dysfunction. Animals Forty-three Cavalier King Charles Spaniels ( CKCS) with MR of varying severity. Methods Privately owned CKCS were prospectively recruited and divided in 4 groups: (1) 12 CKCS with minimal MR; (2) 9 CKCS with mild MR; (3) 11 CKCS with moderate-severe MR; and (4) 11 CKCS with moderate-severe MR and clinical signs compatible with heart failure. Dogs underwent blood sampling, echocardiography, blood pressure ( BP) recordings, and flow-mediated vasodilation ( FMD) measurements. The effect of progressive MR on FMD was determined by multivariate analyses. Results Flow-mediated vasodilation decreased with progression of MR. Group 4 (4.79 ± 3.22%) had significantly lower FMD than groups 1 (10.40 ± 4.58%) and 2 (10.14 ± 3.67%) ( P < .005) and group 3 (6.79 ± 3.98%) had a significantly lower FMD than group 1 ( P = .03). Increasing left ventricular end-diastolic diameter ( P = .0004, R2 = 0.27) and the combination of age ( P = .01) and body weight ( P = .002) (R2 = 0.31) were significantly associated with reduced FMD. FMD did not correlate with sex, BP, or plasma markers. Conclusions and Clinical Importance Reduced FMD indicates that increased disease severity in CKCS with MMVD is associated with development of endothelial dysfunction which might be a future therapeutic and/or diagnostic target. [ABSTRACT FROM AUTHOR]

OBJECTIVES The outcome in dogs with pulmonary hypertension associated with natural Angiostrongylus vasorum infection is unclear. This study aimed to report long-term outcome of dogs with A. vasorum and pulmonary hypertension, and to evaluate factors associated with pulmonary hypertension development. It was hypothesised that dogs with pulmonary hypertension had a shorter survival time than dogs without pulmonary hypertension. METHODS Retrospective review of clinical records of dogs diagnosed with A. vasorum. Dogs were classified as having or not having pulmonary hypertension based on clinical signs and imaging findings. Signalment, signs and outcome were recorded. DNA obtained from banked samples was genotyped for the PDE5a: E90K polymorphism, a possible factor in development of pulmonary hypertension. RESULTS The proportion of dogs with moderate-to-severe pulmonary hypertension and A. vasorum infection in the study population was 14 · 6%. No difference in the population characteristics or PDE5a genotype was detected between dogs with and without pulmonary hypertension. Dogs with pulmonary hypertension had a significantly shorter survival time (P = 0 · 006) and a greater risk of death within 6 months of diagnosis (odds ratio 12 · 5, 95% confidence interval 2 · 1 to 74 · 9; P = 0 · 0053). CLINICAL SIGNIFICANCE A. vasorum-associated pulmonary hypertension is an important problem in naturally infected dogs and has a negative effect upon survival. [ABSTRACT FROM AUTHOR]

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Aims: To evaluate the prevalence of subclinical cardiomyopathy and cardiac mortality in a research colony of non-purebred cats, established as a model of the wider cat population in New Zealand., Methods: All apparently healthy, compliant, non-pregnant, non-neonatal cats in the colony at the Centre for Feline Nutrition (Massey University, Palmerston North, NZ) underwent physical examination and echocardiography using a 4.4-6.2-MHz probe by a board-certified veterinary cardiologist. Cardiac phenotype was classified following current guidelines. Hypertrophic cardiomyopathy (HCM) phenotype was defined as an end-diastolic left ventricular wall thickness ≥ 6 mm. Colony mortality data from February 2012 to February 2022 was reviewed to determine cardiac mortality., Results: Cats (n = 132; 65 females and 67 males) included in the study had a median age of 4.1 (IQR 3.0-8.0) years. Thirty-two (24%) cats had a heart murmur, and three (2%) cats had an arrhythmia. Echocardiography revealed heart disease in 24 (18.2%) cats, including 23 with an HCM phenotype and one with a restrictive cardiomyopathy phenotype. Of the cats with the HCM phenotype, 3/23 had systemic hypertension or hyperthyroidism or both, and these cats were excluded from the final diagnosis of HCM (20/132; 15.2 (95% CI = 9.5-22.4)%).Between 2012 and 2022, 168 colony cats died, with 132 undergoing post-mortem examination. Heart disease was considered the cause of death in 7/132 (5.3%; 95% CI = 2.2-10.6%) cats; five had HCM, one a congenital heart defect, and one myocarditis. The overall prevalence of death related to HCM in the colony during this period was 3.8% (95% CI = 1.2-8.6%). Three cats with HCM and the cat with a congenital heart defect died unexpectedly without prior clinical signs, while congestive heart failure was observed prior to death in two cats with HCM and the cat with myocarditis. Additionally, 30/132 (22.7%) cats had cardiac abnormalities but died for non-cardiac reasons., Conclusions: Subclinical cardiomyopathy, specifically HCM, was common in cats in the colony. Given that the colony originated as a convenience selection of non-purebred cats in New Zealand, the true prevalence of HCM in the wider New Zealand population is likely to fall within the 95% CI (9.5-22%). The proportion of deaths of colony cats due to HCM was lower (3.8%) supporting the conclusion that subclinical cardiomyopathy may not progress to clinical disease causing death., Clinical Relevance: Veterinarians should be aware of the high prevalence of subclinical HCM when treating cats., Abbreviations: CAM: Systolic anterior motion of the chordae tendineae; CFN: Centre for Feline Nutrition; HCM: Hypertrophic cardiomyopathy; LA/Ao: Left atrial to aortic ratio; LV FS: Left ventricular fractional shortening; LVIDd: Left ventricular internal diameters in end-diastole; LVIDs: Left ventricular internal diameter in end-systole; LVWT: Max Maximum left ventricular wall thickness; SAM: Systolic anterior motion of the mitral valve; 2D: Two-dimensional.

Background: The proportion of cats with hypertrophic cardiomyopathy (HCM) that lose systolic anterior motion of the mitral valve (SAM) in the long term is unknown., Hypothesis/objectives: Cats with HCM will lose SAM in the long term. Loss of SAM will be associated with greater age, longer scan-interval, and altered left ventricular (LV) dimensions., Animals: Sixty unsedated cats with HCM, not receiving beta blockers or pimobendan., Methods: A retrospective cohort study from 2 referral centers. Cats were eligible if they had been diagnosed with HCM and had a repeat echocardiogram ≥1 year later. Clinical and echocardiographic data of the left heart variables were collected., Results: Thirty-eight cats had SAM at the initial scan. After a median follow-up time of 2.1 years (range: 1.0-5.9), 7 cats had lost SAM (18%) and 5 cats (23%) gained SAM. On follow-up, cats with SAM at the initial scan had a larger left atrium (P = .037), lower left atrial fractional shortening (P = .014), greater LV internal diameter in end-systole (P = .002), and lower LV fractional shortening (P < .001). Four cats with SAM developed congestive heart failure. There were no new cases of congestive heart failure or change in left heart variables in cats without SAM at the initial scan. The gain or loss of SAM was not associated with age or time between scans., Conclusions and Clinical Importance: Similar proportions of cats gained or lost SAM. Cats with SAM at baseline had more evidence of disease progression than cats without SAM., (© 2024 The Author(s). Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Recently, hypertrophic cardiomyopathy (HCM) in Sphynx cats has been associated with a variant in the gene encoding Alström syndrome protein 1 (ALMS1). The primary aims of this study were to describe the prevalence of HCM in Sphynx cats in New Zealand, and to assess the association between HCM and the ALMS1 variant in this population. In this prospective study, 55 apparently healthy Sphynx cats from registered Sphynx breeders and pet owners in New Zealand were screened by a cardiologist. A total of 42 of these cats had a repeat cardiac examination after median 1.8 years (range: 1.6-2.2). The frequency of the ALMS1 variant was 70.9% (11 homozygous and 28 heterozygous). At the median age of 5.8 years (range: 2.4-13.1), the prevalence of HCM was 40% (20 out of 55 cats). Three cats with HCM died during the study with congestive heart failure. All three cats had focal but extensive myocardial ischemia or infarction at necropsy. The ALMS1 variant was not associated with the HCM diagnosis. In summary, HCM was common in the studied cohort, suggesting Sphynx cats are predisposed to this disease. While the ALMS1 variant was also frequently detected, it was not associated with HCM in this population.

Hypertrophic cardiomyopathy (HCM) affects both humans and cats and exhibits considerable interspecies similarities that are exemplified by underlying pathological processes and clinical presentation to the extent that developments in the human field may have direct relevance to the feline disease. Characteristic changes on histological examination include cardiomyocyte hypertrophy and interstitial and replacement fibrosis. Clinically, HCM is characterised by significant diastolic dysfunction due to a reduction in ventricular compliance and relaxation associated with extracellular matrix (ECM) remodelling and the development of ventricular hypertrophy. Studies in rodent models and human HCM patients have identified key protein mediators implicated in these pathological changes, including lumican, lysyl oxidase and TGF-β isoforms. We therefore sought to quantify and describe the cellular location of these mediators in the left ventricular myocardium of cats with HCM and investigate their relationship with the quantity and structural composition of the ECM. We identified increased myocardial content of lumican, LOX and TGF-β2 mainly attributed to their increased expression within cardiomyocytes in HCM cats compared to control cats. Furthermore, we found strong correlations between the expressions of these mediators that is compatible with their role as important components of cellular pathways promoting remodelling of the left ventricular myocardium. Fibrosis and hypertrophy are important pathological changes in feline HCM, and a greater understanding of the mechanisms driving this pathology may facilitate the identification of potential therapies.

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., (© 2023 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: The natural history of hypertrophic cardiomyopathy (HCM) in cats has been mainly studied in cats referred for suspected heart disease, which can skew the results towards cats with clinical signs. Few data are available on factors associated with development of HCM in cats., Hypotheses: (1) Clinical variables can predict which cats will develop HCM; (2) HCM in cats not referred for suspected heart disease is associated with a low rate of cardiovascular events., Animals: One hundred seven cats from rehoming centers without a history of clinical signs of cardiac or systemic disease at the time of adoption., Methods: Prospective longitudinal study. After rehoming, shelter cats were reexamined for serial echocardiograms. Cox regression analysis was used to identify predictors of development of HCM in cats that were normal at baseline. Adverse cardiovascular events including heart failure, thromboembolism, or sudden death were recorded., Results: Cats were monitored for a median of 5.6 [1.2-9.2] years. At baseline, 68/107 cats were normal, 18/107 were equivocal and 21/107 had HCM. Nineteen cats developed HCM during the study period. The factors at baseline associated with increased hazard of developing HCM were lower left atrial fractional shortening, higher left ventricular fractional shortening, and higher body weight. Cardiovascular events were observed in 21% of cats with HCM., Conclusions and Clinical Importance: Cardiovascular events were common in cats with HCM from a rehoming center study sample. Lower left atrial systolic function appears to precede overt HCM., (© 2022 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: There is a lack of clinical data on hypertrophic cardiomyopathy (HCM) in dogs., Hypothesis/objectives: To investigate signalment, clinical signs, diagnostic findings, and survival in dogs with HCM., Animals: Sixty-eight client-owned dogs., Methods: Retrospective multicenter study. Medical records were searched between 2003 and 2015. The diagnosis of left ventricular (LV) hypertrophy was made by echocardiographic examination., Results: Three hundred and forty-five dogs with LV hypertrophy were identified, of which 277 were excluded. The remaining 68 dogs were 0.3 to 14 years old and predominantly <10 kg (85%), and without a sex predilection. Twenty-four % were Shih Tzu and 24% terrier breeds. Most (80%) had a systolic heart murmur. Owner-determined exercise intolerance (37%) and syncope (18%) were most commonly reported signs. The majority (84%) of dogs had symmetrical LV hypertrophy, whereas asymmetrical septal and LV free wall hypertrophy was observed in 9% and 6% of dogs, respectively. Isolated basal interventricular septal hypertrophy was not observed. Commonly recorded were systolic anterior motion of the mitral valve (60%) and LV diastolic dysfunction (89% of dogs where diastolic function was evaluated). Six dogs died unexpectedly, and 3 developed congestive heart failure. Known survival times were between 1 day and 114 months after diagnosis., Conclusions and Clinical Importance: Hypertrophic cardiomyopathy in dogs should be considered as a differential diagnosis if LV hypertrophy is identified. Small breed dogs are overrepresented, and it is uncommon for dogs with HCM to develop CHF although sudden death can occur., (© 2022 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)