ACVIM consensus statement guidelines for the classification, diagnosis, and management of cardiomyopathies in cats

Relationship Between Cardiac Troponin I Concentration and Myocardial Function in Hypertrophic Cardiomyopathy Cats With or Without Left Ventricular Outflow Tract Obstruction

Hypertrophic cardiomyopathy (HCM) is the most common cardiac disease in cats. HCM is classified into obstructive HCM (HOCM) and non-obstructive HCM (HNCM) forms based on the presence or absence of left ventricular outflow tract obstruction (LVOTO). In humans, LVOTO is a known poor prognostic factor and a target for therapeutic intervention. In contrast, LVOTO has been reported not to contribute to prognosis in cats. This study demonstrated significant correlations between cTnI levels and a maximal LV outflow tract velocity (LVOTV). This finding suggests that LVOTO is associated with myocardial cell injury.

Diagnostic Value of Echocardiography in Cats With and Without Ultrasonographic Evidence of Renal Infarction

BACKGROUND

Revisiting the association between heart disease and renal infarction (RI) in cats is relevant to determine whether those with RI should undergo echocardiographic screening.

OBJECTIVE

Compare the relative frequency of echocardiographically detectable heart disease and other comorbidities in cats with and without ultrasonographic evidence of RI.

ANIMALS

A total of 826 cats that underwent concurrent abdominal ultrasonography and transthoracic echocardiography and were assigned a cardiac diagnosis.

METHODS

Two-center cross-sectional study with a study population recruitment period from January 1, 2011 to June 15, 2021. Demographic, clinical, clinicopathologic, and ultrasonographic data were recorded. Available echocardiographic images were reviewed to assign a standardized cardiac diagnosis. Occult heart disease was defined as structural heart disease without clinical signs of congestive heart failure. Risk factors for RI were evaluated by univariable or multivariable logistic regression.

RESULTS

The relative frequency of structural heart disease in cats with and without RI was 63% (114/181) and 46% (297/645), respectively (adjusted odds ratio [OR] 95% confidence interval [CI], 1.6; 1.2-2.3). Older age (p = 0.03), higher maximum end-diastolic left ventricular wall thickness (p = 0.02), higher systolic blood pressure (p = 0.02), auscultable cardiac abnormalities other than murmur (p = 0.04), and diagnosis of acute kidney injury (p = 0.002), chronic kidney disease (p = 0.005), and occult heart disease (OR [95% CI], 2.4 [1.7-3.4]; p ≤ 0.001) were associated with increased risk of RI. Strength and statistical significance of associations varied by site.

CONCLUSIONS AND CLINICAL IMPORTANCE

Occult heart disease is more frequent in cats with RI, and echocardiographic screening of these cats should be considered.

Multimodal Imaging and Clinical Features of Aortic Dissection in a Cat

An 11-year-old male castrated cat was presented for dyspnoea. Cardiomegaly and pulmonary oedema were identified radiographically. Echocardiography identified lesions of suspected aortic dissection consisting of a false lumen filled with echogenic material at the level of the aortic valve with aortic insufficiency. The cat developed pericardial effusion and chylothorax three months after the initial diagnosis. A computed tomography exam revealed a wall defect allowing connection between the true and beak-, spiral-shaped false lumen compressing the true lumen, which led to a diagnosis of aortic dissection. In addition, aortic wall calcification from the aortic root to the ascending aorta was identified. Ten weeks after the scan, the cat collapsed and died shortly after hospitalisation. The post-mortem examination revealed full-thickness aortic dissection of 2 mm and a beak-shaped lumen surrounding the true lumen, consistent with computed tomography findings. A histopathologic exam revealed aortic dissection at the tunica media, myocyte hypertrophy and endocardial fibrosis. This case report describes clinical, multimodal imaging and histopathological features of aortic dissection in a cat and is the first to describe the corresponding computed tomography and post-mortem findings. Aortic dissection should be considered as a differential diagnosis when true and false lumen is identified on echocardiographic and computed tomography tests.

A Real-world Pharmacovigilance Study Of FDA Adverse Event Reporting System (FAERS) Events For Gender Of Voriconazole Drugs

To detect the gender variations in adverse events (AEs) of voriconazole, promote personalised medicine.A normalized dataset from Q1 2004 to Q4 2022 from the US Food and Drug Administration's Adverse Event Reporting System (FAERS) was analyses. The reporting odds ratio (ROR), proportional reporting ratio (PRR), and P value were used to examine data from the FAERS database to detect risk signals and quantify the presence and extent of gender variations in voriconazole adverse events.A total of 7670 cases (female/male (2785/4885)) of adverse reactions to voriconazole were analysed, and drug interaction (ROR 1.30 (1.10,1.54)), death and sudden death (ROR 1.31 (1.06,1.61)), actinic keratosis (ROR 1.98 (1.10,3.57)) were found to be significantly more frequent in male patients than in female patients.We found that gender was a determinant in voriconazole-related AEs using FAERS. Our results require future validation due to the inherent limits of this open data source, but they also identify potential contributing elements for a customised side effect profiling.

Clinical and echocardiographic variables associated with the type of congestive heart failure manifestation in cats

INTRODUCTION/OBJECTIVES

The aim of this study was to determine clinical and echocardiographic findings associated with congestive heart failure (CHF) manifestation type in cats and to assess impact on the risk of CHF recurrence and survival.

ANIMALS, MATERIALS AND METHODS

A retrospective medical record review of 135 cats with CHF was conducted. Cats were grouped based on CHF manifestation type. Associations between CHF manifestation and clinical and echocardiographic variables were assessed using a Fisher's test and analysis of variance. Comparisons between CHF manifestations were performed using a pairwise Fisher's test with Bonferroni-Holm adjustment and Tukey's honestly significant difference method after analysis of variance.

RESULTS

Congestive heart failure manifestation was associated with sex (P=0.045), history of increased respiratory rate (P=0.006), effort (P=0.001), and signs of arterial thromboembolism (P=0.004). Significant differences between left atrium-to-aorta ratio (P=0.043), diastolic right ventricular internal dimension (P=0.001), systolic right ventricular internal dimension (P=0.015), tricuspid annular plane systolic excursion (P=0.044), and presence of non-specific cardiomyopathy phenotype (P=0.001) were identified among CHF groups. Cats with ascites as their CHF manifestation had significantly higher median diastolic right ventricular internal dimension (9.9 mm) and systolic right ventricular internal dimension (6.6 mm) on pairwise comparison than cats with other CHF manifestations. Congestive heart failure manifestation did not have a statistically significant association with survival but did with time to CHF recurrence (P=0.008).

STUDY LIMITATIONS

Retrospective design, small sample size, and potential misclassification of CHF manifestation type are limitations of this study.

CONCLUSIONS

Congestive heart failure manifestation type is associated with various clinical and echocardiographic findings in cats with heart disease.

Dilated cardiomyopathy phenotype in a 10-week-old Oriental shorthair kitten

A 10-week-old female Oriental shorthair was referred due to stunted growth, weight loss, dyspnea, and reduced activity levels compared to her littermates. Thoracic radiography revealed a markedly enlarged cardiac silhouette and a diffuse unstructured interstitial pulmonary pattern, presumably due to cardiogenic pulmonary edema. Echocardiography showed marked left- and right-sided ventricular dilation, decreased contractility, and enlargement of both atria, without any identifiable congenital defects. Pleural and peritoneal effusion were also present. Based on these findings, a presumptive diagnosis of both left- and right-sided congestive heart failure due to a dilated cardiomyopathy phenotype was made. Cardiovascular pathological examination confirmed the echocardiographic findings. Additionally, mild interstitial myocardial fibrosis was present in the left ventricle, both atria, the interventricular septum, and, to a minimal extent, in the right ventricle. Moderate endocardial fibrosis was observed in the left atrium and left atrial appendage, while mild endocardial fibrosis was present in the left ventricle. Both antemortem and postmortem evaluations did not provide clear evidence of the underlying cause. Therefore, we consider this a rare case of feline juvenile idiopathic dilated cardiomyopathy with secondary reactive endocardial and myocardial fibrosis.

Assessment of longitudinal systolic function using tissue motion annular displacement in cats with hypertrophic cardiomyopathy: a prospective case-control study

ObjectivesThe aim of this study was to investigate left ventricular (LV) longitudinal systolic function in cats with hypertrophic cardiomyopathy (HCM) and healthy control cats using tissue motion annular displacement (TMAD).MethodsThe study included 26 control cats and 21 HCM cats. All cats underwent assessment using two-dimensional echocardiography, M-mode echocardiography, pulsed-wave Doppler, tissue Doppler imaging techniques, longitudinal strain and TMAD.ResultsGlobal TMAD and percentage (%) global TMAD were not influenced by breed, sex, age or heart rate. Mean global TMAD and % global TMAD significantly decreased in the HCM group (2.86 ± 0.86 mm and 11.46% ± 3.37%, respectively) compared with the control group (3.95 ± 0.89 mm and 16.12% ± 2.94%, respectively) (P <0.001 for both), suggesting LV longitudinal systolic dysfunction in HCM cats. LV fractional shortening showed no difference between the control (52.76% ± 11.63%) and the HCM groups (59.80% ± 13.51%) (P = 0.061). Global TMAD and % global TMAD were significantly correlated with global longitudinal strain (P <0.001). The intraclass correlation coefficient of global TMAD and % global TMAD was considered moderate.Conclusions and relevanceGlobal TMAD and % global TMAD were significantly decreased in cats with HCM compared with the control group, and were sensitive and repeatable techniques for evaluating LV longitudinal systolic dysfunction in cats with HCM.

Metabolic abnormalities and reprogramming in cats with naturally occurring hypertrophic cardiomyopathy

BACKGROUND AND AIMS

The heart is a metabolic organ rich in mitochondria. The failing heart reprograms to utilize different energy substrates, which increase its oxygen consumption. These adaptive changes contribute to increased oxidative stress. Hypertrophic cardiomyopathy (HCM) is a common heart condition, affecting approximately 15% of the general cat population. Feline HCM shares phenotypical and genotypical similarities with human HCM, but the disease mechanisms for both species are incompletely understood. Our goal was to characterize global changes in metabolome between healthy control cats and cats with different stages of HCM.

METHODS

Serum samples from 83 cats, the majority (70/83) of which were domestic shorthair and included 23 healthy control cats, 31 and 12 preclinical cats with American College of Veterinary Internal Medicine (ACVIM) stages B1 and B2, respectively, and 17 cats with history of clinical heart failure or arterial thromboembolism (ACVIM stage C), were collected for untargeted metabolomic analysis. Multiple linear regression adjusted for age, sex and body weight was applied to compare between control and across HCM groups.

RESULTS

Our study identified 1253 metabolites, of which 983 metabolites had known identities. Statistical analysis identified 167 metabolites that were significantly different among groups (adjusted P < 0.1). About half of the differentially identified metabolites were lipids, including glycerophospholipids, sphingolipids and cholesterol. Serum concentrations of free fatty acids, 3-hydroxy fatty acids and acylcarnitines were increased in HCM groups compared with control group. The levels of creatine phosphate and multiple Krebs cycle intermediates, including succinate, aconitate and α-ketoglutarate, also accumulated in the circulation of HCM cats. In addition, serum levels of nicotinamide and tryptophan, precursors for de novo NAD+ biosynthesis, were reduced in HCM groups versus control group. Glutathione metabolism was altered. Serum levels of cystine, the oxidized form of cysteine and cysteine-glutathione disulfide, were elevated in the HCM groups, indicative of heightened oxidative stress. Further, the level of ophthalmate, an endogenous glutathione analog and competitive inhibitor, was increased by more than twofold in HCM groups versus control group. Finally, several uremic toxins, including guanidino compounds and protein bound putrescine, accumulated in the circulation of HCM cats.

CONCLUSIONS

Our study provided evidence of deranged energy metabolism, altered glutathione homeostasis and impaired renal uremic toxin excretion. Altered lipid metabolism suggested perturbed structure and function of cardiac sarcolemma membrane and lipid signalling.

Experimental Models of Hypertrophic Cardiomyopathy: A Systematic Review

To advance research in hypertrophic cardiomyopathy (HCM), and guide researchers in choosing the optimal model to answer their research questions, we performed a systematic review of all models investigating HCM induced by gene variants ranging from animal models to human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Our research question entailed: which experimental models of HCM have been created thus far, and which major hallmarks of HCM do they present? Out of the 603 included papers, the majority included animal models, though a clear transition to hiPSC-CM is visible since 2010. Our review showed that only 36 mouse models showed minimal 4 out of 6 HCM disease markers (cell/cardiac hypertrophy, disarray, fibrosis, diastolic dysfunction, and arrhythmias), while only 17 hiPSC-CM models showed 3 out of 4 HCM cell characteristics. Our review emphasizes the need to better report data on sample size, sex, age, and relevant disease-specific characteristics.

Post-carvedilol myocardial function in cats with obstructive hypertrophic cardiomyopathy

Introduction

Hypertrophic cardiomyopathy (HCM) is the most prevalent cardiac disease in cats, and one phenotype includes obstructive HCM with dynamic left ventricular outflow tract obstruction (DLVOTO). Myocardial function has been reported to be lower in cats with obstructive HCM than in non-obstructive HCM. Carvedilol, because of its pharmacological action, is expected to reduce the pressure gradient associated with DLVOTO, but no previous reports have studied its effects on myocardial function. This study aimed to evaluate myocardial function in cats with obstructive HCM with left ventricular outflow tract obstruction treated by carvedilol administration.

Methods

This retrospective observational study included 16 cats with obstructive HCM and subsequent treatment of DLVOTO with carvedilol. In addition to conventional echocardiography, strain and strain rates in the left ventricular longitudinal and circumferential directions were measured using layer-specific two-dimensional speckle tracking echocardiography. Each variable was then compared before and after carvedilol medication.

Results

Systolic anterior motion of the mitral valve disappeared in 14 cats and all cats showed resolved DLVOTO with maximal left ventricular outflow tract blood flow velocity of <2.5 m/s after carvedilol administration (P < 0.01). Circumferential strain in the epicardial layer and in the whole layer was significantly increased after carvedilol administration (P < 0.01, P = 0.04, respectively). In contrast, systolic longitudinal strain showed no significant difference between before and after carvedilol administration.

Conclusion

Treatment of obstructive HCM with carvedilol improved DLVOTO and myocardial function without a negative inotropic effect. Carvedilol may be effective in treating cats with obstructive HCM.

Clinical-Diagnostic and Therapeutic Advances in Feline Hypertrophic Cardiomyopathy

A comprehensive literature review was conducted to summarise existing evidence and the latest therapeutic advancements in feline HCM. The disease phenotype is characterised by the development of concentric hypertrophy, which is variable but often asymmetric, primarily affecting the left ventricle. The HCM is marked by diastolic dysfunction, resulting in a reduced intracavitary internal diameter due to the disordered alignment of cardiomyocytes and excessive collagen deposition, which thickens the myocardial tissue and impairs relaxation. There is strong evidence supporting the role of genetic mutations in sarcomeric genes in the development of HCM. Clinical signs vary but are frequently associated with congestive heart failure (CHF) and ATE. Diagnosis is based on a combination of clinical evaluation, laboratory tests, and imaging studies, although certain aspects of the disease remain insufficiently understood and require further research. Therapeutic management focuses on controlling clinical signs, slowing disease progression, and improving both quality of life and life expectancy. However, ongoing studies are essential to refine diagnostic strategies and explore novel treatment options for better disease management.

Emergency Dyspnea in 258 Cats: Insights from the French RAPID CAT Study

Dyspnea is common in feline emergency medicine. Dyspneic cats are often unable to tolerate additional diagnostic tests upon admission. The aim of this study was to determine the relative frequency of the causes of severe dyspnea in cats and to identify clinical indicators that could guide immediate management. Records of 312 severely dyspneic cats admitted over a 5-year period to our institution's emergency and critical care unit were retrospectively reviewed. The cause of dyspnea was identified for 258 cats, representing 83% of the cases. This study focused solely on these 258 cats. Respiratory causes accounted for 33% of cases, followed by cardiac causes (25%) and both traumatic and neoplastic causes (21% each). Pleural effusion was present in 39% of the cats, with various origins: cardiac (38%), respiratory (pyothorax, feline infectious peritonitis, 30%), neoplastic (23%), and traumatic (9%). Male cats were significantly overrepresented in the cardiac and respiratory groups. The median age differed according to the cause (2 years for traumatic causes, 6 years for respiratory causes, and approximately 11 years for cardiac and neoplastic causes). Cats with cardiac disease were significantly more often hypothermic. Hyperthermia was not systematically indicative of an infectious process. No clinical element (temperature, heart rate, cardiac auscultation, etc.) allowed for predicting the cause of dyspnea. In-hospital mortality was 44%, varying according to the cause (78% for neoplastic causes, 40% for traumatic causes, 37% for cardiac causes, and 30% for respiratory causes). In conclusion, the four main categories of causes were represented in approximately equal proportions, which contrasts with the results of the British RAPID CAT study, where cardiac causes accounted for nearly two-thirds of dyspnea cases. In the dyspneic cats in this series, the clinical presentation did not allow clinicians to identify a particular cause. This highlights the importance of non-invasive examinations such as POCUS (point-of-care ultrasound), which has become a routine test in emergency medicine. However, this importance should not lead to underestimating the continued value of radiography when the cat's clinical condition allows for image acquisition.

The Pathological and Histopathological Findings in Cats with Clinically Recognised Hypertrophic Cardiomyopathy Are Related to the Severity of Clinical Signs and Disease Duration

Hypertrophic cardiomyopathy (HCM) is the most frequent type of cardiac disease in cats. Due to its high prevalence and risk of sudden and severe signs, the disease is an important topic of various research. Despite the focus on the clinical course of the disease, studies presenting the pathological and histopathological patterns are rare. The study was conducted as a retrospective analysis of feline patients subjected to postmortem examination in the Cardiopathology Unit due to a clinical diagnosis of hypertrophic cardiomyopathy based on echocardiographic examination and ACVIM guidelines. Thirty-four cats clinically diagnosed with HCM were enrolled in the study. During the postmortem examination, hearts were subjected to gross morphometric and histopathological evaluation. Our results show that the histopathological pattern in cats with clinically stated HCM is very diverse, affecting both ventricles and atria. The histopathological picture is more complex in animals diagnosed earlier and treated for a longer period. Moreover, it is generally unrelated to wall thickness, with only left ventricular fibrosis affecting the thickness of the left ventricular wall. In conclusion, further research combining clinical and pathological results is required to unambiguously determine the histopathological remodelling that takes place in the myocardium of cats with hypertrophic cardiomyopathy.

Genetic counseling in veterinary medicine: towards an evidence-based definition for the small animal practice

BACKGROUND

In human medicine, questions regarding heritable disorders are dealt with by clinical geneticists and genetic counselors and both the field, their roles and the tools they use are well-defined. Even though the prevalence of diseases is far higher and scientific literature agrees on expectations towards an increased importance, this does not seem to be the case in veterinary medicine. While we hypothesize that there will be an overlap, some characteristics uniquely linked to veterinary medicine might not be covered.

METHODS

To investigate this in-depth and in an attempt to define the field, we compared the internationally accepted definitions and its subparts on genetic counseling in human medicine with what is found in veterinary literature and what was seen in cats and dogs presented at our dedicated small animals clinical genetics/genetic counseling clinic. The results were used in a stepwise analysis that lead to a set of three potential definitions (i.e. on what genetic counseling is, who provides it and which tools are used) that fullfill four criteria (i.e. definitions have to be clear/self-explanatory, minimally sufficient, complete and valid).

RESULTS

The short version of the definition of genetic counseling in veterinary medicine is: "Genetic counseling is the process of helping animal owners and breeders understand - and adapt to - the medical, psychological, familial implications of genetic contributions to disease." Genetic counseling in small animal practice is currently provided by veterinarians and the tools that are used, can be divided in five categories. The signalment of the patients revealed that both cats (30%) and dogs (70%) and various breeds, the two sexes (37% males, 63% females) and all age categories (puppy/kitten-senior) were represented. Furthermore, 73% of the patients were referred by or needed to be referred to other disciplines.

CONCLUSION

These definitions are derived from human and veterinary literature, and an evaluation based on patient data has demonstrated that these definitions meet all the criteria of a correct definition (i.e. clear, minimally sufficient, complete and valid). With these definitions and case descriptions, our aim is to contribute to the formal foundation of genetic counseling in veterinary medicine.

Retrospective Evaluation of Subpleural Consolidations Using Lung Ultrasound in 634 Dogs and 347 Cats

BACKGROUND

Human literature describes vascular patterns in various types of lung consolidations; however, these changes have not been analyzed in dogs and cats. This retrospective analysis of medical records aimed to describe vascular patterns observed in the airless subpleural lung tissue of dogs and cats and to compare these patterns to various lung consolidations and clinical diagnoses according to parenchymal and vascular criteria described in human literature.

ANIMALS

This study included 347 cats and 634 dogs.

METHODS

This was a retrospective study encompassing medical records obtained between 2018 and 2023. Lung ultrasound was performed in dogs and cats and cases with different sonographically identified airless subpleural lung tissue were selected. Airless subpleural lung tissue was categorized into five types of consolidations: shred, nodule, wedge sign, mass, and tissue sign. Further classification was based on the parenchymal criteria, the presence or absence of bronchograms and the vascular patterns identified within these regions. Bronchograms were classified as air bronchograms (dynamic and/or static), fluid bronchograms, mixed fluid and air bronchograms, and/or absence of bronchograms. Vascular patterns were classified as tree-like, residual, chaotic, "vascular sign", and whether they were continuous with and extended from the chest wall or not.

CONCLUSIONS AND CLINICAL IMPORTANCE

It is possible to identify and characterize airless subpleural lung tissue in cats and dogs based on the parenchymal and vascular characteristics.

Reference intervals of two-dimensional speckle tracking-derived endocardial global longitudinal strain analysis in 132 healthy cats

INTRODUCTION

The assessment of left ventricular myocardial deformation and function by two-dimensional speckle tracking-derived strain analysis is an established method in human cardiology. It also progressively gains recognition in veterinary cardiology in both dogs and cats.

OBJECTIVES

The objectives of this study were to create reference intervals for two-dimensional speckle tracking echocardiography (STE)-derived endocardial global longitudinal strain (GLS) in a population of healthy adult cats of different breeds. Influences of heart rate, body weight, and age were investigated.

ANIMALS

A total of 132 healthy, adult cats were included in this study.

MATERIALS AND METHODS

Left apical two-, three-, and four-chamber views were obtained prospectively for GLS measurements using two-dimensional speckle tracking performed with cardiac performance analysis. Potential influence of body weight, heart rate, and age was analyzed, and the interobserver and intra-observer variability of the measurements was determined.

RESULTS

Endocardial GLS values were not significantly influenced by body weight (P=0.102), heart rate (P=0.144), or age (P=0.075). A reference interval for GLS of -21.18% to -37.50% (±4.12) was determined. The interobserver and intra-observer variability showed excellent agreement.

DISCUSSION AND CONCLUSIONS

Two-dimensional STE is a feasible technique for the evaluation of cardiac myocardial deformation and systolic function in cats. Showing an excellent interobserver and intra-observer agreement, two-dimensional STE is a promising method for clinical analysis of cardiac deformation in cats.

Identification of novel genetic variants associated with feline cardiomyopathy using targeted next-generation sequencing

Cardiomyopathies are the most common heritable heart diseases in cats and humans. This study aimed to identify novel genetic variants in cats with hypertrophic cardiomyopathy (HCM) and restrictive cardiomyopathy (RCM) using a targeted panel of genes associated with human cardiomyopathy. Cats were phenotyped for HCM/RCM by echocardiography ± necropsy. DNA was extracted from residual blood, and targeted next-generation sequencing was performed on two separate feline cohorts: an across-breed cohort (23 healthy cats and 21 HCM-affected pedigree or Domestic Shorthair cats), and a within-breed cohort of Birman pedigree cats (14 healthy, 8 HCM-affected, and 6 RCM-affected). Genome Analysis Toolkit was used for variant discovery. Genomic association analyses, including the covariates breed, age, and sex, were conducted to identify genetic variants of interest. We identified genetic variants associated with both HCM and RCM susceptibility in the sarcomeric genes ACTC1, ACTN2, MYH7, TNNT2 and the non-sarcomeric gene CSRP3 in the Birman pedigree cats. These findings suggest that, as proposed in humans, there is at least partial overlap in the genetic background between the HCM and RCM phenotypes in cats. These findings offer potential insights for comparative cardiac research and translational medicine.

Congenital pulmonic and aortic stenosis in Newfoundland dogs: Results of a 14-year French cardiovascular screening program (921 dogs)

INTRODUCTION

Aortic stenosis (AS) and pulmonic stenosis (PS) are two of the most common canine congenital heart diseases (CHD), with a high relative risk for Newfoundland dogs to develop inherited subvalvular AS. For this reason, a cardiovascular screening program has been set up by the French Newfoundland kennel club in order to manage mattings and reduce AS prevalence.

MATERIALS AND METHODS

The records of untreated and non-anesthetized adult Newfoundland dogs screened between 2010 and 2023 were retrospectively reviewed. All dogs underwent physical examination and standard transthoracic echocardiography with concomitant ECG tracing. All examinations were reviewed by one single board-certified specialist in cardiology.

RESULTS

A total of 921 dogs were screened during the study period (female:male sex ratio = 1.94, median age [IQR] = 1.9 years [1.6-2.7], body weight = 55.0 kg [50-60]). For most dogs (90.6% for AS and 91% PS), a single examination was required to obtain a definitive cardiac status, although most operators (122/133 = 91.7%) were non-specialist general practitioners. Out of the 921 screened dogs, 913/921 (99.1%) and 919/921 (99.8%) were respectively free of AS and PS, with no AS and PS detection during the last 3 years of the program. The inbreeding coefficient, which was assessed from the pedigree analysis of all screened dogs except one, was not significantly different between dogs with either AS (0.59%; P = 0.86) or PS (0.39%; P = 0.72) and those without any arterial stenosis (0.39%).

CONCLUSION

This 14-year cardiovascular screening program has experienced a strong involvement of veterinarians, breeders, and owners throughout France. Unlike reports from other European and North American countries, this program suggests the low and decreasing prevalence of both AS and PS in the Newfoundland breed in France.

Subcutaneous Furosemide Therapy for Chronic Management of Refractory Congestive Heart Failure in Dogs and Cats

Reduced efficacy of oral diuretics in the treatment of congestive heart failure (CHF) can be secondary to reduced enteral drug absorption. The aim of this study was to determine the efficacy of subcutaneous (SC) furosemide administration to control the signs of refractory CHF in dogs and cats and to assess the feasibility of this route of administration. The clinical records of 13 dogs and 17 cats with a history of refractory CHF treated with subcutaneous (SC) furosemide were reviewed retrospectively. Administration of SC furosemide was offered as an alternative therapy when animals experienced an unsatisfactory clinical response to oral diuretics despite multiple dose adjustments and when, for this reason, pet owners were considering euthanasia. The satisfactory control of the animal's breathing rate and effort and overall pet owner's satisfaction were observed in all cases. Following administration of SC furosemide, the median survival time was 106 (95% CI: 22-154) days in dogs and 89 (95% CI: 35 to 749) days in cats. This study showed that furosemide administered subcutaneously appears to be an efficacious and feasible therapeutic option for providing control of the signs of cardiac congestion in both dogs and cats with a previous unsatisfactory response to oral diuresis.

A New, Easy-to-Learn, Fear-Free Method to Stop Purring During Cardiac Auscultation in Cats

BACKGROUND

Purring in cats can interfere with cardiac auscultation. If the produced noise is loud enough, purring makes it impossible to perform a meaningful auscultation as it is much louder than heart sounds and murmurs. Our study introduced and tested a new, simple, fear-free, cat-friendly method to stop purring during auscultation.

METHODS

The technique involves grasping the cat's larynx from ventral with one hand, while simultaneously holding the stethoscope in the other hand to perform the auscultation.

RESULTS

The incidence of purring was evaluated in 582 cats, in a veterinary teaching hospital and in a cat-friendly private practice. Fifty-one (8.8%) cats were purring during their physical examination. The tested method had a success rate of 89% in terminating purring. A comparison between investigators (a veterinary student versus an experienced veterinary cardiology specialist) showed no significant difference in the effectiveness of the method (p = 0.57). The incidence of purring was not significantly different between the teaching hospital and the cat-friendly practice (p = 1.00). Sick and older cats purred more often than healthy and younger cats.

CONCLUSIONS

This new, simple, easy-to-master method is an improvement over previously reported techniques and supports the need for stress-free, cat-friendly handling in veterinary practice.

A pilot study investigating serum carnitine profile of cats with preclinical hypertrophic cardiomyopathy

This study aimed to prospectively investigate the hypothesis that myocardial energy metabolism changes in the early stages of feline hypertrophic cardiomyopathy (HCM) by evaluating the blood carnitine profiles. Fourteen client owned cats with HCM stage B1 and 22 clinically healthy cats were included in this study. Total-carnitine, free-carnitine, acylcarnitine, and acylcarnitine/free-carnitine ratio (AF ratio) in serum were measured in both groups. No significant differences were observed in total-carnitine, free-carnitine, and acylcarnitine concentrations between the groups. However, the AF ratio in the HCM group was significantly lower than that of the control group (P=0.02). The lower serum AF ratio in cats with early-stage HCM, may suggest an alteration in their myocardial energy metabolism.

A New Graphical Method for Displaying Two-Dimensional Echocardiography Results in Dogs: Comprehensive Analysis of Results of Diagnostic Imaging Organized in a BOX (CARDIOBOX)

INTRODUCTION AND OBJECTIVE

Rapid and efficient interpretation of echocardiographic findings is critical in clinical decision-making. This study aimed to design and validate a new graphical method, called CARDIOBOX, to represent echocardiographic findings in dogs.

METHODS

A prospective, observational, exploratory cohort study was conducted over three years. The design of CARDIOBOX was based on baseline values obtained from 802 healthy dogs and 2165 ill dogs. Using these data, a graph consisting of nine boxes was built to show the intervals of the different echocardiographic measurements. Validation of the method was performed by a survey of 55 veterinarians, who compared the use of CARDIOBOX with the use of numerical tables.

RESULTS

CARDIOBOX demonstrated significantly faster interpretability (p < 0.05) without reducing its effectiveness. In addition, the staff surveyed considered it easy to use and interpret.

CONCLUSIONS

The introduction of CARDIOBOX emerges as a resource that facilitates rapid and efficient interpretation of echocardiographic findings in dogs. This new graphical method is presented as a valuable tool for veterinary professionals in clinical decision-making in the field of veterinary cardiology.

Prevalence of cardiomyopathy and cardiac mortality in a colony of non-purebred cats in New Zealand

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.

Cardiovascular changes in Persian cats with polycystic kidney disease: a study of cardiac troponin I, echocardiography and blood pressure

OBJECTIVES

Cardiovascular complications are well known in humans with autosomal dominant polycystic kidney disease (PKD), but limited data exist for cats. This study aimed to assess echocardiographic changes, cardiac troponin I (cTnI) levels and systolic blood pressure (SBP) in Persian cats with PKD to detect early cardiac abnormalities.

METHODS

In total, 52 Persian and mixed-Persian cats were enrolled, with 26 cats in the control group and 26 diagnosed with PKD via ultrasound due to the unavailability of genetic testing. Although genetic testing is the gold standard for definitive diagnosis, this study utilised high-sensitivity ultrasound as an alternative diagnostic tool. This method aligns with existing literature supporting its effectiveness in detecting PKD, particularly in regions where genetic testing is not accessible. Echocardiographic examinations employed M-mode and two-dimensional echocardiography to measure the diastolic thickness of the interventricular septum and the left ventricular free wall. Doppler ultrasonography was used to measure SBP and cTnI serum levels were determined using a Monobind-ELISA kit.

RESULTS

Median SBP and cTnI levels in PKD cats were 155 mmHg and 85.80 ng/l, respectively, which was significantly higher than the control group (P ⩽0.001). Interventricular septum in systole, as well as diastolic thickness of the interventricular septum and the left ventricular free wall, was significantly elevated in PKD cats compared with controls (P ⩽0.001). No significant differences were observed in other echocardiographic parameters.

CONCLUSIONS AND RELEVANCE

Asymptomatic PKD-affected Persian cats exhibited elevated SBP and cardiac structural changes; however, the clinical significance of these findings remains uncertain due to a lack of long-term follow-up. While early cardiac changes may be present, further research is necessary to establish their clinical relevance and guide appropriate management strategies. Monitoring PKD cats is advised, but a direct clinical impact is not confirmed at this stage.

Frequency and progression of azotemia during acute and chronic treatment of congestive heart failure in cats

BACKGROUND

Azotemia is common in cats with congestive heart failure (CHF) and might be exacerbated by diuretic therapy.

HYPOTHESIS/OBJECTIVES

Determine frequency, risk factors, and survival impact of progressive azotemia in cats treated for CHF.

ANIMALS

One hundred and sixteen client-owned cats with kidney function testing performed at least twice during acute or chronic CHF treatment.

METHODS

Serum creatinine (sCr) and electrolyte concentrations were determined at multiple clinical timepoints to detect azotemia and kidney injury (KI; sCr increase ≥0.3 mg/dL). Furosemide dosage between timepoints was calculated. Multivariable modeling was performed to identify predictors of KI, change in serum biochemistry results, and survival.

RESULTS

Azotemia was common at all timepoints, including initial CHF diagnosis (44%). Kidney injury was documented in 66% of cats. Use of a furosemide continuous rate infusion was associated with increased risk of KI during hospitalization (odds ratio, 141.6; 95% confidence interval [CI], 12.1-6233; P = .01). Higher furosemide dosage was associated with increase in sCr during hospitalization (P = .03) and at first reevaluation (P = .01). Treatment with an angiotensin converting enzyme inhibitor was associated with fewer lifetime KI events (P = .02). Age in years was the only variable associated with shorter survival (hazard ratio, 1.1; 95% CI, 1.0-1.1; P = .03). Neither sCr nor KI were associated with long-term outcome.

CONCLUSIONS AND CLINICAL IMPORTANCE

Azotemia and KI were common in cats during CHF treatment but did not impact survival.

A novel technique to characterize procoagulant platelet formation and evaluate platelet procoagulant tendency in cats by flow cytometry

Introduction

Cardiogenic arterial thromboembolism (CATE) is a life-threatening complication of hypertrophic cardiomyopathy (HCM) with a high mortality rate. As the primary responders in hemostasis, platelets play a crucial role in the progression of CATE. Procoagulant platelets are a subpopulation of activated platelets that facilitate thrombin generation to strengthen thrombus structure. Since their discovery, procoagulant platelets have gained a considerable amount of attention due to their potential role in thromboembolic complications. Uncovering the key phenotypic markers and agonists underlying the procoagulant response in feline platelets may provide diagnostic and therapeutic insights in the treatment of CATE. However, species differences in platelet physiology and the sensitive nature of feline platelets pose some significant challenges in studying procoagulant platelets in cats.

Objectives

To first devise a flow cytometric method to sequentially assess procoagulant platelet markers and to identify agonists that could induce procoagulant platelet phenotypes. Furthermore, a novel scoring system was established to evaluate the procoagulant tendency of platelets in cats.

Methods

Platelets were isolated from eight healthy cats and activated by thrombin in the presence or absence of collagen (COL) and convulxin (CVX). The following markers were measured sequentially by flow cytometry: (1) loss of mitochondrial membrane potential (ΔΨm), (2) phosphatidylserine (PS) externalization, and (3) P-selectin upregulation.

Results

Thrombin in the presence of CVX significantly reduced ΔΨm and induced P-selectin upregulation (p = 0.0078, p = 0.0128, respectively). In addition, thrombin-treated platelets in the presence of COL and CVX augmented PS externalization significantly (p = 0.043, p = 0.0172, respectively). Of the agonists tested, thrombin and CVX resulted in the highest procoagulant tendency score with 75% cats reaching a score ≥2/3. The number of cats with a procoagulant tendency score of 2 or 3 for thrombin and thrombin + COL was 4/8 (50%) and 5/8 (62.5%), respectively.

Discussion

Sequential analysis of procoagulant markers via flow cytometry may be an effective technique for studying procoagulant platelets in cats.

Clinical, electrocardiographic, and diagnostic imaging features and outcomes in cats with electrocardiographic diagnosis of ventricular pre-excitation: a retrospective study of 23 cases (2010-2022)

INTRODUCTION/OBJECTIVES

Ventricular pre-excitation (VPE) occurs when atrial electrical impulses prematurely excite the ventricles through an aberrant muscle bundle known as an accessory pathway (AP). Orthodromic atrioventricular reciprocating tachycardia is a re-entrant, narrow complex supraventricular tachycardia (SVT), maintained through retrograde conduction over an AP. The study aimed to describe patient signalments, clinical signs, electrocardiographic (ECG) and diagnostic imaging features, treatments, prognostic variables, and outcomes in cats with ECG diagnosis of VPE.

ANIMALS

Twenty-three cats diagnosed with VPE between January 2010 and August 2022 were included in this study.

MATERIALS AND METHODS

This was a multicenter, retrospective study with 23 cats diagnosed with VPE between January 2010 and August 2022. Ventricular pre-excitation diagnosis was based on ECG evidence of shortened PR interval, delta wave, and prolonged QRS duration. The median survival time (MST) was estimated by the Kaplan-Meier curve. Log-rank tests were performed to assess for an association between clinical signs or presence of structural heart disease on the MST.

RESULTS

Fourteen (60.8%) cats with VPE also had SVT documented on ECG, with seven of 14 with ECG confirmation of orthodromic atrioventricular reciprocating tachycardia. Four (17.4%) cats had suspected AP-mediated tachyarrhythmia based on associated clinical signs. Common presenting signs included collapse (15/23; 65.2%) and respiratory distress (14/23; 60.8%). Five (21.7%) cats were asymptomatic. Heart rate during SVT ranged from 310 to 420 bpm (median: 375 bpm). Initial treatment included atenolol (10/18), sotalol (5/18), diltiazem (2/18), and amiodarone (1/18). From the date of diagnosis, MST was 1872 days (5.1 years).

CONCLUSIONS

The majority of cats with VPE also had symptomatic SVT. The prognosis for cats with VPE is considered good with an MST of greater than five years.

Pharmacodynamics of single-dose omecamtiv mecarbil administered intravenously in clinically healthy cats

Background

Omecamtiv mecarbil (OM), a selective cardiac myosin activator, is gaining attention as a potential heart failure (HF) treatment because it can enhance cardiac contractility without adverse effects. Concerns were raised about arrhythmias with conventional HF treatments in cats. Despite OM's promise in veterinary medicine, no studies have confirmed its efficacy in cats.

Aim

This study aimed to investigate the pharmacodynamics of OM in cats.

Methods

Five clinically healthy cats were used. OM's efficacy was examined in three doses: 0.1, 0.25, and 1.0 mg/kg. To minimize the effect on heart rates, the cats were under general anesthesia, and baseline measurements were taken after the heart rate and blood pressure had stabilized. OM was administered as a single intravenous injection. Echocardiography was performed 15, 30, 60, 90, and 120 minutes after administration. Heart rate and blood pressure were measured before each echocardiographic examination.

Results

The heart rates decreased at all doses; significant reductions were seen at 0.25 and 1.0 mg/kg. All doses enhanced cardiac contractility, showing a dose-dependent effect. Blood pressure remained unchanged.

Conclusion

OM enhances cardiac contractility in cats, with 0.25 mg/kg being the optimal dose.

Situational syncope caused by vomiting in a cat

A 14-year-old spayed female mixed-breed cat weighing 3.4 kg was admitted to the Tokyo University of Agriculture and Technology Animal Medical Center for syncope after vomiting. Echocardiography, electrocardiography, and thoracic radiography revealed no abnormalities. Holter electrocardiography showed a paroxysmal high-grade atrioventricular block coinciding with the vomiting. Based on these findings, the cat was diagnosed as having situational syncope with paroxysmal high-grade atrioventricular block triggered by vomiting, which improved with antiemetic treatment alone. The cat subsequently died of chronic kidney disease approximately 3 years and 4 months after the initial diagnosis. This is the first reported case of situational syncope triggered by vomiting in a cat.

Systemic reactive angioendotheliomatosis mimicking hypertrophic cardiomyopathy in a domestic shorthair cat

A two-year-old, 3.9-kg, male castrated, domestic shorthair cat presented to The Ohio State University Veterinary Medical Center for acute onset neurological signs. During hospitalization, he was diagnosed with an American College of Veterinary Internal Medicine (ACVIM) stage B1 hypertrophic cardiomyopathy phenotype on echocardiogram. His clinical signs acutely worsened, including seizure activity and panting, and he was euthanized. Necropsy revealed the histopathologic diagnosis of systemic reactive angioendotheliomatosis, which notably severely affected the myocardium. In this case report, we present the antemortem diagnostic results and postmortem necropsy results of this rare condition in cats. This case demonstrates that echocardiographic assessment of the heart in cats affected by systemic reactive angioendotheliomatosis may lead to the false diagnosis of hypertrophic cardiomyopathy and thus should be considered as a differential diagnosis in cats with symmetrical left ventricularl wall thickening on echocardiography.

Clinical evaluation of a digital stethoscope with simultaneous phonocardiography and electrocardiography in cats

A smartphone-based technology combining a digital stethoscope (DS) with simultaneous phonocardiography (PCG) and 1-lead electrocardiogram (ECG) is available. The aim of the present study was to evaluate the sensitivity and specificity of the DS for the detection of heart disease in cats considering transthoracic echocardiography as gold standard. The study is prospective and observational inlcuding 42 client-owned cats. All cases underwent auscultation with a conventional stethoscope (CS), recording with the DS, 6-lead ECG and echocardiography. All the recordings were blindly reviewed. The agreement with standard methods was assessed using the Cohen's kappa and the Bland-Altman test. The Fisher's exact test was used to test the effect of shaving on tracings' quality. Intraoperator and interoperator variability were assessed with Cohen's k and Fleiss' k, respectively. Audio recordings obtained with DS were interpretable in 100% of the cats. The agreement between DS and echocardiography in detecting heart disease was substantial (k = 0.714), while between CS and echocardiography the agreement was moderate (k = 0.571). Intraoperator and interoperator agreement was almost perfect (k = 0.904; k = 0.867, respectively). The ECG tracings recorded with the DS were interpretable in 83% of the cats and the device was reliable in assessing basic ECG measurements. No significant differences were found in the quality of the audio and ECG tracings in relation to the shaving condition. Based on the efficacy of detecting cardiac murmurs and gallop sound, the DS can be considered a reliable tool for cardiac auscultation in cats, producing good quality audio and ECG tracings also suitable for possible remote interpretation.

Differences in the Impact of Left Ventricular Outflow Tract Obstruction on Intraventricular Pressure Gradient in Feline Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common form of cardiomyopathy in cats, and heart failure occurs as diastolic dysfunction progresses. HCM in cats is broadly classified as non-obstructive and obstructive hypertrophic cardiomyopathy, depending on the presence or absence of outflow tract obstruction. Measurement of the intraventricular pressure differences (IVPD) using color M-mode (CMM) has attracted attention as a reliable diastolic index as it correlates with catheterization, the gold standard for the assessment of diastolic performance. Because IVPD is affected by the size of the heart, the intraventricular pressure gradient (IVPG) index, which is unaffected by heart size, is by calculated by dividing IVPD by LV length. In the present study, CMM IVPG was used to non-invasively assess diastolic impairment in cats with obstructive hypertrophic cardiomyopathy. This study was conducted on 10 control cats and 18 cats in the HCM group. Although no severe left atrial enlargement was observed in the HCM group, the basal IVPG was significantly increased in the HOCM group compared to the control group. Although IVPD typically suggests impaired diastolic function and reduced ventricular compliance, the significant increase observed in the HOCM group compared to controls may suggest an indirect elevation in left atrial pressure, likely secondary to left ventricular outflow tract obstruction. The increase in IVPG in HOCM, as shown in this study, is a pathological effect of left ventricular outflow tract obstruction that cannot be detected by conventional echocardiographic indices, and evaluating IVPG is useful to evaluate cardiac function from a perspective that differs from conventional methods.

The prevalence of murmurs and gallop sounds in anemic cats

BACKGROUND

There is little information on the prevalence of auscultatory abnormalities in anemic cats. This study aimed to describe the prevalence of cardiac murmurs and gallop sounds in a population of anemic and nonanemic cats presenting to an emergency room (ER) and to assess whether the prevalence of auscultatory abnormalities was influenced by the severity of anemia.

KEY FINDINGS

Records of cats presenting to an ER between May 2021 and May 2022 or receiving a blood transfusion between September 2019 and January 2022 were retrospectively analyzed for presence of a murmur or gallop sound. Cats with known structural heart disease were excluded. A murmur was found in 56 of 185 (30%) anemic cats compared with 11 of 102 (11%) nonanemic cats (p < 0.001), with a higher proportion in cats with PCV <16% (p < 0.001). Twenty-five of 185 (14%) anemic cats had a gallop compared with 4 of 102 (4%) nonanemic cats (p = 0.009), with the highest proportion in cats with PCV 11%-20% (p < 0.001). Echocardiography was performed on 17 of 185 anemic cats; 8 had normal echocardiograms and 9 demonstrated evidence of chamber dilation without left ventricular wall thickening, consistent with anemia.

CONCLUSIONS

Abnormalities on auscultation are common in anemic cats presenting to the ER, with a higher prevalence in more severely anemic cats.

The effects of alfaxalone on cardiac and pulmonary vascular size in cats evaluated by thoracic radiography and echocardiography

Alfaxalone is a neuroactive steroid that modulates the GABAA receptor, which has shown recent widespread use as a sedative and anesthetic agent in cats, especially in patients being screened for cardiovascular disease. This prospective, partially blinded, randomized experimental study aimed to determine if sedation with alfaxalone would alter the appearance of the cardiac silhouette or pulmonary vasculature on thoracic radiographs or echocardiographic indices of cardiac or pulmonary vascular size. Eleven apparently healthy adult cats were recruited from a research colony. Four-view thoracic radiographs and an echocardiogram were performed at baseline and following a 5 mg/kg intramuscular dose of alfaxalone. Vertebral heart score (VHS) and cranial and caudal lobar pulmonary vascular measurements were obtained at both time points by two independent blinded observers, and these were analyzed using two-way ANOVA. The nonblinded echocardiographer obtained echocardiographic measurements at both time points, which were analyzed using a paired t-test or Wilcoxon signed rank test. No significant differences were identified in VHS measurements or echocardiographic parameters between baseline and sedated cats. In healthy cats, alfaxalone does not appear to significantly affect the cardiovascular structures evaluated via thoracic radiography or echocardiography.

Evaluation of potential novel biomarkers for feline hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common cardiomyopathy in cats. The diagnosis can be difficult, requiring advanced echocardiographic skills. Additionally, circulating biomarkers (N-terminal pro-B type natriuretic peptide and cardiac troponin I) have several limitations when used for HCM screening. In previous work, we identified interleukin 18 (IL-18), insulin-like growth factor binding protein 2 (IGFBP-2), brain-type glycogen phosphorylase B (PYGB), and WNT Family Member 5 A (WNT5A) as myocardial genes that show significant differential expression between cats with HCM and healthy cats. The products of these genes are released into the circulation, and we hypothesized that IL-18, IGFBP-2, PYGB, and WNT5A serum RNA and protein concentrations differ between healthy cats, cats with subclinical HCM, and those with HCM and congestive heart failure (HCM + CHF). Reverse transcriptase quantitative polymerase chain reaction (RTqPCR) and enzyme-linked immunosorbent assay (ELISA) were applied to evaluate gene and protein expression, respectively, in the serum of eight healthy controls, eight cats with subclinical HCM, and six cats with HCM + CHF. Serum IGFBP-2 RNA concentrations were significantly different among groups and were highest in cats with subclinical HCM. Compared to healthy controls, serum IL-18 and WNT5A gene expression were significantly higher in cats with HCM + CHF, and WNT5A was higher in cats with subclinical HCM. No differences were observed for PYGB. These results indicate that further investigation via large scale clinical studies for IGFBP-2, WNT5A, and IL-18 may be valuable in diagnosing and staging feline HCM.

Longitudinal assessment of systolic anterior motion of the mitral valve in cats with hypertrophic cardiomyopathy

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.

Evaluation of a rapid test for point-of-care detection of cardiac troponin I in serum of healthy and diseased dogs and cats

OBJECTIVES

(1) To compare the results of a rapid test for qualitative detection of cardiac troponin I (cTnI) values >1 ng/mL with those obtained using a reference quantitative method and (2) to perform a semiquantitative assessment of rapid test results using this point-of-care (POC) assay.

DESIGN

Prospective cross-sectional study from April 2015 to November 2020.

SETTING

Secondary referral hospital.

ANIMALS

Eighty dogs and 20 cats, with and without cardiovascular disease.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Serum samples were obtained, and cTnI rapid test was conducted in parallel with chemiluminescence assay (reference standard). Positive results from the rapid test were further classified as mild and strong positives, based on subjective assessment of the color intensity of the test line. Rapid test was deemed valid in all patients. There was agreement for positive samples between the qualitative and quantitative techniques in 31 dogs and 5 cats, and for negative samples in 43 dogs and 13 cats, resulting in a strong and moderate agreement, respectively. There was a significant difference between color scale groups.

CONCLUSIONS

The rapid test assessed provides a feasible POC option to determine concentrations of cTnI >1 ng/mL in dogs and cats and shows a moderate to strong agreement with a validated conventional quantitative assay. Furthermore, semiquantitative assessment allows estimation of the magnitude of the elevation.

CRISPR/Cas9 gene editing in induced pluripotent stem cells to investigate the feline hypertrophic cardiomyopathy causing MYBPC3/R820W mutation

Hypertrophic cardiomyopathy (HCM) is the most common heart disease in domestic cats, often leading to congestive heart failure and death, with current treatment strategies unable to reverse or prevent progression of the disease. The underlying pathological processes driving HCM remain unclear, which hinders novel drug discovery. The aim of this study was to generate a cellular model of the feline HCM-causing MYBPC3 mutation R820W. Using CRISPR/Cas9 gene editing we introduced the R820W mutation into a human induced pluripotent stem cell (iPSC) line. We differentiated both homozygous mutant clones and isogenic control clones to cardiomyocytes (iPSC-CMs). Protein quantification indicated that haploinsufficiency is not the disease mechanism of the mutation. Homozygous mutant iPSC-CMs had a larger cell area than isogenic controls, with the sarcomere structure and incorporation of cMyBP-C appearing similar between mutant and control iPSC-CMs. Contraction kinetic analysis indicated that homozygous iPSC-CMs have impaired relaxation and are hypocontractile compared to isogenic control iPSC-CMs. In summary, we demonstrate successful generation of an iPSC model of a feline MYBPC3 mutation, with the cellular model recapitulating aspects of HCM including cellular hypertrophy and impaired relaxation kinetics. We anticipate that further study of this model will lead to improved understanding of the disease-causing molecular mechanism, ultimately leading to novel drug discovery.

Left atrial fractional shortening in cats: a comparison between two echocardiographic views

INTRODUCTION/OBJECTIVES

Left atrial fractional shortening (LAFS%) is a widely used index of left atrial systolic function in cats that has been shown to predict development of hypertrophic cardiomyopathy (HCM) and cardiac mortality. It can be determined by two methods: from an M-mode right parasternal short-axis view (LAFS%RPSA-MM) or two-dimensional right parasternal long-axis four-chamber view (LAFS%RPLA-2D). We aimed to assess the agreement between LAFS%RPSA-MM and LAFS%RPLA-2D in cats and to evaluate the correlation between LAFS%RPSA-MM and LAFS%RPLA-2D and left ventricular systolic performance.

ANIMALS, MATERIALS, AND METHODS

One hundred and seventeen cats were enrolled in the study: 40 control, 41 HCM stage B (asymptomatic), and 36 HCM stage C (symptomatic) cats. This was a retrospective case-control study. Bland-Altman analysis was used to assess agreement between LAFS%RPSA-MM and LAFS%RPLA-2D across the whole cohort and in cats with asymptomatic and symptomatic HCM. Correlation analysis was used to assess associations between LAFS% methods and forward aortic flow, left ventricular fractional shortening, and aortic root motion.

RESULTS

The LAFS% determined by LAFS%RPSA-MM and LAFS%RPLA-2D was similar (P=0.8), but Bland-Altman analysis showed wide limits of agreement between methods. There was a good correlation between LAFS%RPSA-MM and LAFS%RPLA-2D and aortic root motion (r = 0.78 and r = 0.71, respectively) and a fair correlation with left ventricular fractional shortening (r = 0.31 and r = 0.29, respectively). None of the methods showed a correlation with indices of aortic flow.

CONCLUSIONS

Our study suggests a poor agreement between LAFS%RPSA-MM and LAFS%RPLA-2D, and thus, these methods should not be used interchangeably. Both echocardiographic methods showed good correlation with aortic root motion.

Feline hypertrophic cardiomyopathy: Does the microRNA-mRNA regulatory network contribute to heart sarcomeric protein remodelling?

Feline primary hypertrophic cardiomyopathy (HCM) is an intrinsic myocardial disease characterized by concentric hypertrophy of the left ventricle. In the present study, we investigated the microRNA-mRNA regulatory network in feline myocardial tissue affected by primary (HCMI) and secondary HCM (HCMII). MRNA expression levels of sarcomeric genes, including, TNNT2, TNNI3, MYH7, MYBPC3, TPM1 and ACTC1 were assessed in the FFPE myocardial tissues. FFPE tissues from healthy cats were sequenced by the NGS, to explore, in the entire non-deposited miRNome, the expression level of microRNAs targeting the complementary sequences of selected sarcomeric mRNAs. The sarcomeric genes TNNT2, MYH7, MYBPC3 and TPM1 showed a statistically significant upregulation in HCMI compared to HCMII (p < .01), except ACTC1 which was downregulated (p < .01); TNNI3 showed no statistically significant difference. In HCMII miR-122-5p, miR-338-3p, miR-484, miR-370-3p, miR-92b-3p, miR-375 and miR-370-3p showed a significant upregulation (p < .01) compared to control. The exception was miR-30a-5p which showed downregulation. Worthy of note is the 4-fold higher expression of miR-370-3p, a key regulator of MYBPC3, in HMCI compared to HMCII. This research does not solve the aetiological mystery of HCM, but it may help to find a way to help diagnose and define the prognosis of HCM in cats.

Atrial septal pouch in cats: first report on interatrial septum anatomical variations

OBJECTIVES

The atrial septal pouch was first recognised in humans in 2006 and, since 2010, has been described in more detail. The first reports on the left-sided atrial septal pouch linked its occurrence with a higher risk of thromboembolic stroke resulting from left atrial thrombus formation. However, subsequent studies have challenged this theory; therefore, the consequences of septal pouch occurrence remain disputed. Currently, in veterinary species, septal pouch occurrence and morphology have been described in sheep and pigs, showing species-related differences. No studies have been conducted on cats. As cats show a species-related risk of aortic thromboembolic disease resulting from left atrial thrombus formation, we aimed to describe the interatrial septum anatomical variations as the first step in the investigation of the relationship between the septal pouch presence and left atrial thrombus formation.

METHODS

The study was conducted on hearts collected post mortem from 80 cats. After formalin fixation and dissection, a detailed anatomical description of the interatrial septum for all cases was followed by a histopathological analysis of the heart in 25 cases. After dissection, the specimens were embedded in paraffin blocks and stained with haematoxylin and eosin, Masson-Goldner trichrome, Picrosirius Red and Movat pentachrome in a routine manner and evaluated via light microscopy.

RESULTS

Our study showed a very high prevalence (95%) of the left-sided septal pouch in cats with a lower incidence (29%) of the right-sided septal pouch. We noted a high morphological variety of the left-sided septal pouch and described anatomical variants not previously reported in the literature.

CONCLUSIONS AND RELEVANCE

The septal pouch is a common anatomical variation of the interatrial septum in cats. Although, based on the current study, we cannot draw further conclusions on the relationship between the left-sided septal pouch and thromboembolic events in cats, the high prevalence of this anatomical entity points to a need of further studies on the topic.

A pilot study of the proarrhythmic effects of pimobendan injection in clinically healthy cats

Pimobendan is not currently approved for use in cats, although its usefulness in feline hypertrophic cardiomyopathy has been suggested. Reports indicate an increase in arrhythmic events following oral administration to healthy cats. Given the greater potency of intravenous administration compared to oral intake, it is conceivable that the incidence of arrhythmias may be increased following pimobendan injection. Therefore, this study aimed to investigate the proarrhythmic effects of pimobendan injection in cats. Five clinically healthy cats underwent physical examination, echocardiography, blood pressure measurements, and 24-hour Holter electrocardiography immediately before and after receiving pimobendan as an intravenous bolus dose of 0.15 mg/kg twice daily for 3 days. Additionally, a 24-hour Holter electrocardiography recording was conducted on the third day of pimobendan or placebo IV administration to assess heart rate, arrhythmias, and heart rate variability. Following pimobendan administration, there was a significant increase in total 24-hour heart rate. Echocardiography revealed a significant increase in mitral valve annulus systolic velocity (S') on the ventricular septal wall side, indicative of enhanced contractility. Only one cat exhibited paroxysmal ventricular tachycardia and an increase in the frequency of arrhythmic events. Conversely, in the remaining cats, a decreasing trend in the number of arrhythmias was observed. These findings indicate that intravenous administration of pimobendan may not be implicated in the onset of arrhythmias. Nevertheless, further research is warranted to explore the effects of intravenous pimobendan administration in cats with myocardial disease.

Resolution of dynamic left ventricular outflow tract obstruction and reversible left ventricular hypertrophy in 4 cats

This case series describes spontaneous resolution of systolic anterior motion of the mitral valve, cessation of a dynamic left ventricular outflow tract obstruction, and reverse cardiac remodeling in 4 young cats. Following initial presentation with or without congestive heart failure, subsequent rechecks documented resolution of systolic anterior motion of the mitral valve and normalization of left heart dimensions. Those cats originally presented with congestive heart failure were successfully weaned off diuretic medications. Atenolol was prescribed to all 4 cats, and all remained on oral atenolol through the final recheck. There was no documented recurrence of progressive heart disease and heart failure in any of the cats. Consideration is given to transient myocardial thickening, spontaneous resolution of mitral valve dysplasia, and response to beta-1 adrenergic antagonism as possible underlying mechanisms. Key clinical message: When presented with young cats with hypertrophic obstructive cardiomyopathy, veterinarians should consider multiple differential diagnoses, as lifespan in these cases may be longer than typically expected for cats with primary hypertrophic cardiomyopathy, even with concurrent congestive heart failure.

Prevalence of Hypertrophic Cardiomyopathy and ALMS1 Variant in Sphynx Cats in New Zealand

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.

Parameters related to diagnosing hypertrophic cardiomyopathy in cats

Background

The initial diagnostic markers are important for general practitioners to identify cats suspected of having cardiac disease, particularly hypertrophic cardiomyopathy (HCM).

Aim

The aim of this study is to investigate the indicators that suggest feline cardiac disease, especially HCM.

Methods

This is a retrospective study, using the data from 354 cats, to identify various clinical parameters that indicate the presence of cardiac disease in cats in order to develop a model to predict the likelihood of HCM in cats. Among all the parameters gathered, heart sound and LA size are the most significant in predicting the likelihood of HCM in cats.

Results

After undergoing statistical analysis, we created a formula that could help screen cats with HCM and normal cats before further diagnosis, such as echocardiography. The formula Y1 = -3.637 +2.448 (LA size) +2.683 (murmur) +1.274 (gallop) is the fittest model with an area under curve from the ROC analysis of 0.889. A new set of data was used to validate the model. This predictive model has 40% accuracy but correctly predicts 90% of the truly normal cats, making this model beneficial in helping veterinarians exclude truly normal cats from cats suspected of having HCM.

Conclusion

The model may assist in distinguishing normal cats from those suspected of having HCM. Further diagnosis with echocardiography remains the gold standard for the final diagnosis of cardiac diseases in cats.

Clinical signs associated with severe ST segment elevation in three cats with a hypertrophic cardiomyopathy phenotype

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.

A Retrospective Study of Sildenafil Administration in 55 Cats with Cardiopulmonary Disease (2009-2021)

Sildenafil is a drug used to successfully manage a variety of cardiopulmonary disorders in people and dogs, but there is limited information on its use in cats. The objective was to review the medical records of cats that received sildenafil as part of their clinical management. Medical records and pharmacy databases were searched for cats that received sildenafil for ≥24 h between 2009 and 2021, and data were collected from medical records. Fifty-five cats received sildenafil for ≥24 h and were included in the study: 43 with primary cardiac disease (acquired, n = 28; congenital, n = 15) and 12 with primary respiratory disease. Side effects possibly attributed to sildenafil were identified in two cats (systemic hypotension, n = 1; polydipsia, n = 1), and sildenafil was discontinued in the cat with hypotension. Sildenafil was discontinued in an additional three cats due to a lack of improvement in clinical signs. No cat was documented to develop worsening pulmonary edema within 72 h of starting sildenafil. Median duration of sildenafil administration was 87 days (range, 2-2362 days). Sildenafil administration in cats appeared to be generally well-tolerated. Studies are needed to determine whether sildenafil administration to cats with cardiopulmonary disease improves the quality of life or survival times.

The Unseen Side of Feline Hypertrophic Cardiomyopathy: Diagnostic and Prognostic Utility of Electrocardiography and Holter Monitoring

Hypertrophic cardiomyopathy (HCM) is a common heart disease in cats, characterized by regional or diffuse hypertrophy of the left ventricular walls, with an uncertain etiology and heterogenous natural history. Several types of rhythm disturbances are often associated with the disease. This study conducts a comprehensive review of the current literature, in order to evaluate the diagnostic and prognostic effectiveness of electrocardiography and Holter monitoring in the management of feline hypertrophic cardiomyopathy. The main subjects of discussion will include general information about HCM and its connection to arrhythmias. We will explore the rhythm disturbances documented in the current literature on Holter monitoring, as well as the techniques used for Holter monitoring. Additionally, the review will cover classical electrocardiography (ECG) and its diagnostic utility. Prognostic indicators and anti-arrhythmic therapy will also be discussed in detail. The findings highlight the importance of understanding arrhythmias in feline HCM for accurate diagnosis, risk assessment, and therapeutic intervention. ECG and Holter monitoring may offer valuable insights into managing feline HCM.

Investigation of coagulation and proteomics profiles in symptomatic feline hypertrophic cardiomyopathy and healthy control cats

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a crucial heart disease in cats. The clinical manifestations of HCM comprise pulmonary edema, dyspnea, syncope, arterial thromboembolism (ATE), and sudden cardiac death. D-dimer and prothrombin time (PT) are powerful biomarkers used to assess coagulation function. Dysregulation in these two biomarkers may be associated with HCM in cats. This study aims to assess D-dimer levels, PT, and proteomic profiling in healthy cats in comparison to cats with symptomatic HCM.

RESULTS

Twenty-nine client-owned cats with HCM were enrolled, including 15 healthy control and 14 symptomatic HCM cats. The D-dimer concentration and PT were examined. Proteomic analysis was conducted by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry and liquid chromatography-tandem mass spectrometry (LC-MS/MS). In symptomatic cats, D-dimer levels were statistically significantly higher (mean ± SEM: 372.19 ng/ml ± 58.28) than in healthy cats (mean ± SEM: 208.54 ng/ml ± 10.92) with P-value of less than 0.01, while PT was statistically significantly lower in symptomatic cats (mean ± SEM: 9.8 s ± 0.15) compared to healthy cats (mean ± SEM: 11.08 s ± 0.23) with P-value of less than 0.0001. The proteomics analysis revealed upregulation of integrin subunit alpha M (ITGAM), elongin B (ELOB), and fibrillin 2 (FBN2) and downregulation of zinc finger protein 316 (ZNF316) and ectonucleoside triphosphate diphosphohydrolase 8 (ENTPD8) in symptomatic HCM cats. In addition, protein-drug interaction analysis identified the Ras signaling pathway and PI3K-Akt signaling pathway.

CONCLUSIONS

Cats with symptomatic HCM have higher D-dimer and lower PT than healthy cats. Proteomic profiles may be used as potential biomarkers for the detection and management of HCM in cats. The use of D-dimer as a biomarker for HCM detection and the use of proteomic profiling for a better understanding of disease mechanisms remain to be further studied in cats.

2024 AAHA Fluid Therapy Guidelines for Dogs and Cats

Fluids are drugs used in veterinary patients capable of producing beneficial therapeutic or inadvertent harmful effects within the body's intravascular, interstitial, and intracellular fluid spaces. The individualized design of a fluid therapy plan requires careful patient assessment and targeted selection of proper fluid types, administration routes, and rates, along with adjustments during therapy tailored specifically as per the individual patient's fluid requirement and therapeutic response. Personalized fluid prescriptions and vigilant patient monitoring help avoid patient morbidity from body fluid deficiencies, fluid excess, and electrolyte derangements and support better patient outcomes. These guidelines provide an overview of fluid dynamics within the fluid spaces of the body, describe various types of fluids and their uses, and outline recommendations for fluid administration for resuscitation, rehydration, and maintenance purposes. The guidelines also outline approaches to fluid therapy for anesthetized patients and reiterate the recommendations of reduced fluid rates in this population of patients. Additionally, the guidelines include practical fluid therapy strategies for patients with various common disorders. The goal of these guidelines is to help veterinary professionals safely and effectively prescribe and administer fluid therapy for canine and feline patients.