Prevalence of heart disease in symptomatic cats: an overview from 1998 to 2005

The protective effect of Bergamot Polyphenolic Fraction on reno-cardiac damage induced by DOCA-salt and unilateral renal artery ligation in rats

To date, the complex pathological interactions between renal and cardiovascular systems represent a real global epidemic in both developed and developing countries. In this context, renovascular hypertension (RVH) remains among the most prevalent, but also potentially reversible, risk factor for numerous reno-cardiac diseases in humans and pets. Here, we investigated the anti-inflammatory and reno-cardiac protective effects of a polyphenol-rich fraction of bergamot (BPF) in an experimental model of hypertension induced by unilateral renal artery ligation. Adult male Wistar rats underwent unilateral renal artery ligation and treatment with deoxycorticosterone acetate (DOCA) (20 mg/kg, s.c.), twice a week for a period of 4 weeks, and 1% sodium chloride (NaCl) water (n = 10). A subgroup of hypertensive rats received BPF (100 mg/kg/day for 28 consecutive days, n = 10) by gavage. Another group of animals was treated with a sub-cutaneous injection of vehicle (that served as control, n = 8). Unilateral renal artery ligation followed by treatment with DOCA and 1% NaCl water resulted in a significant increase in mean arterial blood pressure (MAP; p< 0.05. vs CTRL) which strongly increased the resistive index (RI; p<0.05 vs CTRL) of contralateral renal artery flow and kidney volume after 4 weeks (p<0.001 vs CTRL). Renal dysfunction also led to a dysfunction of cardiac tissue strain associated with overt dyssynchrony in cardiac wall motion when compared to CTRL group, as shown by the increased time-to-peak (T2P; p<0.05) and the decreased whole peak capacity (Pk; p<0.01) in displacement and strain rate (p<0.05, respectively) in longitudinal motion. Consequently, the hearts of RAL DOCA-Salt rats showed a larger time delay between the fastest and the lowest region (Maximum Opposite Wall Delay-MOWD) when compared to CTRL group (p<0.05 in displacement and p <0.01 in strain rate). Furthermore, a significant increase in the levels of the circulating pro-inflammatory cytokines and chemokines (p< 0.05 for IL-12(40), p< 0.01 for GM-CSF, KC, IL-13, and TNF- α) and in the NGAL expression of the ligated kidney (p< 0.001) was observed compared to CTRL group. Interestingly, this pathological condition is prevented by BPF treatment. In particular, BPF treatment prevents the increase of blood pressure in RAL DOCA-Salt rats (p< 0.05) and exerts a protective effect on the volume of the contralateral kidney (p <0.01). Moreover, BPF ameliorates cardiac tissue strain dysfunction by increasing Pk in displacement (p <0.01) and reducing the T2P in strain rate motion (p<0.05). These latter effects significantly improve MOWD (p <0.05) preventing the overt dyssynchrony in cardiac wall motion. Finally, the reno-cardiac protective effect of BPF was associated with a significant reduction in serum level of some pro-inflammatory cytokines and chemokines (p<0.05 for KC and IL-12(40), p<0.01 for GM-CSF, IL-13, and TNF- α) restoring physiological levels of renal neutrophil gelatinase-associated lipocalin (NGAL, p<0.05) protein of the tethered kidney. In conclusion, the present results show, for the first time, that BPF promotes an efficient renovascular protection preventing the progression of inflammation and reno-cardiac damage. Overall, these data point to a potential clinical and veterinary role of dietary supplementation with the polyphenol-rich fraction of citrus bergamot in counteracting hypertension-induced reno-cardiac syndrome.

Frequency of arrhythmias detected in 9440 feline electrocardiograms by breed, age, and sex

OBJECTIVES

The purpose of this study was to describe the frequency of arrhythmias detected in unsedated feline patients from general practice settings.

ANIMALS

A total 10,638 feline electrocardiograms (ECGs) were retrospectively collected of which 9440 met the inclusion criteria.

METHODS

Recordings were evaluated by a board-certified cardiologist. If an arrhythmia was present in the ECG tracing, the cardiologist categorized the arrhythmia using pre-established keywords.

RESULTS

At least one arrhythmia was observed in 249 cases (2.64%, 95% confidence interval (CI): 2.34-2.98, 249/9440), with the most common arrhythmia encountered being ventricular premature complexes (1.63%, 95% CI: 1.39%-1.91%, 154/9440). Ragdoll cats had the highest odds of arrhythmia (odds ratio (OR): 3.17, 95% CI: 1.43-6.17, P=0.036). Both geriatric (Age: 13+ years, OR: 1.70, 95% CI: 1.24-2.34, P=0.013) and senior (Age: 10-13 years, OR: 1.68, 95% CI: 1.19-2.37, P=0.003) cats had higher odds of having an arrhythmia than adult cats. The odds of male cats having an arrhythmia were slightly higher than female (OR: 1.36, 95% CI: 1.06-1.76, P=0.018).

CONCLUSIONS AND RELEVANCE

Of the 9440 ECGs included in this study, at least one arrhythmia was detected in 249 distinct cases. Arrhythmias were more common in older cats, male cats and the Ragdoll cat breed. While it is important to note that the presence of an arrhythmia alone does not always indicate the presence of heart disease, further research on the association between breed cardiac health is needed.

Supravalvular mitral stenosis in a cat: clinical, diagnostic and pathologic findings

The present case report describes a rare case of a cardiac abnormality diagnosed as Supravalvular Mitral Stenosis in an asymptomatic cat. An 11-years old cat was presented for orthopedic evaluation, and during general clinical examination a heart rate of 180 bpm and left diastolic cardiac murmur grade III-IV/VI, between the mitral and aortic foci, were found. Radiographic, echocardiographic, angiocardiographic and post-mortem (the patient died during anesthesia performed to diagnose the orthopedic condition) magnetic resonance and pathologic findings are reported herein.

Deep learning-based diagnosis of feline hypertrophic cardiomyopathy

Feline hypertrophic cardiomyopathy (HCM) is a common heart disease affecting 10-15% of all cats. Cats with HCM exhibit breathing difficulties, lethargy, and heart murmur; furthermore, feline HCM can also result in sudden death. Among various methods and indices, radiography and ultrasound are the gold standards in the diagnosis of feline HCM. However, only 75% accuracy has been achieved using radiography alone. Therefore, we trained five residual architectures (ResNet50V2, ResNet152, InceptionResNetV2, MobileNetV2, and Xception) using 231 ventrodorsal radiographic images of cats (143 HCM and 88 normal) and investigated the optimal architecture for diagnosing feline HCM through radiography. To ensure the generalizability of the data, the x-ray images were obtained from 5 independent institutions. In addition, 42 images were used in the test. The test data were divided into two; 22 radiographic images were used in prediction analysis and 20 radiographic images of cats were used in the evaluation of the peeking phenomenon and the voting strategy. As a result, all models showed > 90% accuracy; Resnet50V2: 95.45%; Resnet152: 95.45; InceptionResNetV2: 95.45%; MobileNetV2: 95.45% and Xception: 95.45. In addition, two voting strategies were applied to the five CNN models; softmax and majority voting. As a result, the softmax voting strategy achieved 95% accuracy in combined test data. Our findings demonstrate that an automated deep-learning system using a residual architecture can assist veterinary radiologists in screening HCM.

Radiographic features of cardiogenic pulmonary oedema in cats with left-sided cardiac disease: 71 cases

OBJECTIVES

The aims of this study were to describe the radiographic features of cardiogenic pulmonary oedema (CPE) in a large group of cats with left-sided cardiac disease, and to determine the association between the radiographic features of CPE and the underlying cardiac disease.

METHODS

Thoracic radiographs of cats with CPE and echocardiographic evidence of left-sided cardiac disease and left atrial enlargement (LAE) were reviewed, and cardiac silhouette, pulmonary vessels and pulmonary parenchyma evaluation were performed. Interstitial and/or alveolar patterns were classified according to their distribution (ie, diffuse, multifocal or focal) and location (ie, craniodorsal, cranioventral, caudodorsal, caudoventral and perihilar). A Student's t-test and Mann-Whitney U-test, or the two-proportion z-test, were used to compare continuous or categorical variables, respectively, between cats affected by the two most represented cardiac diseases, namely hypertrophic cardiomyopathy (HCM) and restrictive cardiomyopathy (RCM).

RESULTS

Seventy-one cats were included; among them, 46 (64.7%) and 13 (18.3%) had presented for HCM and RCM, respectively. Subjective and objective cardiomegaly, and subjective and objective LAE were detected in 97.2% and 91.9% of cats and in 80.3% and 40.6% of cats, respectively. Pulmonary artery abnormalities, in particular caudal pulmonary artery dilation, were found in 77.5% of cats. Pulmonary artery to pulmonary vein ratio = 1 was found in 71.8% and 55% cats on right lateral and ventrodorsal or dorsoventral views, respectively. Interstitial (57.8%) and mixed interstitial-alveolar (38%) pattern, multifocal (84.5%) and symmetrical (75%) distribution with prevalent ventrocaudal (65.6% of cats) and ventrocranial (60.9% of cats) locations were most frequently observed. No difference was found for any of these radiographic features between cats with HCM and RCM.

CONCLUSIONS AND RELEVANCE

Moderate-to-severe cardiomegaly and LAE, caudal pulmonary artery and vein dilation, as well as a ventral, multifocal and symmetrical interstitial pulmonary pattern, were the main radiographic features of CPE in evaluated cats. Underlying cardiac disease did not influence the aforementioned radiographic features.

A Questionnaire Survey on Long-Term Outcomes in Cats Breed-Screened for Feline Cardiomyopathy

Feline cardiomyopathy (FCM) is an important contributor to feline morbidity and mortality. This explorative follow-up questionnaire study was aimed at investigating the long-term outcome in cats breed-screened for FCM (BS-FCM) in three Nordic countries. Records of cats with ≥1 BS-FCM between 2004−2015 were included. Of the 1113 included cats, 104/1113 (9.3%) had developed FCM at some time-point. Fifty-nine of the 104 (56.7%) FCM cats were diagnosed within the screening program (ScreenFCM), and 33/59 (55.9%) of these were diagnosed at the first BS-FCM. ScreenFCM cats or with an owner-reported FCM diagnosis at a later time-point had a higher risk of cardiac-related death compared to cats that never developed FCM. A shorter lifespan was found in ScreenFCM cats compared to those with normal screen results (p < 0.001). Times to all-cause mortality were shorter (p < 0.001) in cats that developed FCM at any time-point compared to those that did not. Non-cardiac morbidities were similar in all screen classification groups. The large proportion of cats that developed FCM at a later time-point underscores the need for repeated screenings later in life. Cats that developed FCM at any time-point had a shorter lifespan, with a similar proportion and in line with the nature of non-cardiac morbidities, compared to those without FCM.

Right atrioventricular valve dysplasia in a meerkat

A 7-y-old, captive, intact female meerkat (Suricata suricatta) was presented with lethargy, decreased appetite, dyspnea, and distended abdomen. At autopsy, the right atrium was markedly dilated, and the right atrioventricular valve (RAV) was dysplastic with shortened or absent chordae tendineae and direct attachment of the valve to the papillary muscles, which, in turn, were fused and abnormally positioned. The right ventricle was considered to be hypertrophied. Also present were hydrothorax, ascites, atelectasis, and hepatic congestion. A diagnosis of RAV dysplasia was made. Histologic findings included hypertrophy of cardiomyocytes and marked centrilobular hepatic congestion and hemorrhage, which were consistent with right-sided heart failure.

Effect of cilobradine in cats with a first episode of congestive heart failure due to primary cardiomyopathy

INTRODUCTION

Heart rate (HR) is often elevated in cats with cardiomyopathies (CMPs). Pharmacologic modulation of HR may reduce cardiac morbidity and mortality.

OBJECTIVES

To investigate the effects of cilobradine vs. placebo, regarding time to cardiac mortality or morbidity in cats with first episode of congestive heart failure (CHF) due to primary CMP.

ANIMALS

Three hundred and sixty-seven client-owned cats with primary CMP that had presented with a first episode of CHF at 50 centers in Europe. Per-protocol population comprised 193 cats (n = 89 cilobradine, n = 104 placebo). An interim analysis for futility was planned.

METHODS

Prospective, randomized, placebo-controlled, double-blinded, multicenter clinical trial. Primary outcome variable was the time to a composite of cardiac mortality or cardiac morbidity.

RESULTS

Median time to primary outcome was 84 days (95% confidence interval [CI]: 63-219 days) in the cilobradine group (CG) and 203 days in the placebo group (95% CI: 145-377 days) with observed hazard ratio of 1.44, indicating a higher hazard for the CG (P = 0.057). Mean HR was 28 beats per minute (bpm) lower at Day 7 (P < 0.0001) and remained 29 bpm lower at Day 360 (P = 0.026) in the CG than that in the placebo group. Although the number of adverse events did not differ, there were more serious adverse events in the CG.

CONCLUSIONS

Heart rate reduction by cilobradine in cats with a first episode of CHF due to primary CMP did not reduce cardiac mortality and morbidity.

[Reversible left ventricular hypertrophy and congestive heart failure due to suspected myocarditis in a cat in the course of FLUTD]

A 2.5-year-old castrated male domestic shorthair cat with a past pertinent history of FLUTD treatment 8 days earlier was presented during the night due to apathy and anorexia. Radiographs, ECG, blood pressure measurement and echocardiography revealed left-sided congestive heart failure, left ventricular concentric hypertrophy, left atrial dilation, severe diastolic dysfunction, hypotension, and vagotonus-associated sinus bradycardia with a first degree AV-block as well as a right bundle brunch block. NT-ProBNP and troponin I concentrations were elevated (NT-ProBNP > 1500 pmol/l, Troponin I 32.87 ng/ml). Presumptive diagnosis was acute myocarditis. Bartonella henselae PCR and Toxoplasma gondii IgM titer were negative. Initial IgG titer amounted to 1:32 (reference range: < 1:32) and on later testing this was negative. FeLV and FIV tests exhibited negative results. Coronavirus testing was not performed because the cat was vaccinated accordingly. A metastatic infection with Proteus mirabilis, which had been isolated from the urine, appeared possible. Alternatively, a hypersensivity reaction to drugs or a stress-induced myocarditis was taken into consideration. The hospitalized cat was treated with furosemide (initialy and in the course of further treatment), theophyllin (initially), continuous infusion with lactated Ringer's solution, pimobendan, and the addition of enrofloxacin to the ongoing amoxicillin/clavulanic acid administration. After 4 days, the cat's general condition improved satisfactorily and blood pressure returned to normal range. Left ventricular hypertrophy resolved, however, diastolic dysfunction as well as left atrial dilation persisted. Within the next 8 weeks, echocardiographic findings and cardiac biomarkers returned to near normal values. All medication was tapered and finally discontinued. During the last recheck examination 7 months following initial presentation, no cardiac changes were apparent.

Estimation of vertebral heart size and cardiothoracic ratio in Persian cats

The study aimed to determine the reference values related to vertebral heart size (VHS) and cardiothoracic ratio (CTR), which are effective in the evaluation of the thorax diseases and especially cardiomegaly of the brachycephalic cats using the morphometric data of thorax and heart obtained from the radiographic images of the thoracic region of the Persian cats. It was determined that lying position during radiography did not affect VHS and CTR values. Also, the sex factor did not have a significance on these values. The fact that the VHS value of 8.16 thoracic vertebrae averagely found in the Persian cats is higher than 7.5 thoracic vertebrae value averagely stated in the studies conducted with the cats of different breeds is considered since the breed is brachycephalic.

Left atrial size and volume in cats with primary cardiomyopathy with and without congestive heart failure

INTRODUCTION/OBJECTIVES

Myocardial diseases are the most common acquired cardiac diseases in cats and may result in left atrial enlargement and congestive heart failure (CHF). Volume calculations have replaced linear measurements for chamber quantification in humans but are not commonly measured in cats. The aims of this retrospective study were to compare the left atrial (LA) size by two-dimensional linear measurements to two-dimensional LA volumes (LAV).

ANIMALS

One hundred sixty-two client-owned cats were included.

MATERIALS AND METHODS

Cats with complete echocardiographic examinations were included and categorized into one of the three groups: healthy, cardiomyopathy (CM), and CHF. Seven measurements of the LA size were performed including minimal and maximal LA-to-aortic ratio (LA:Ao) and LAV and also maximal left atrial diameter (LAD).

RESULTS

Cats were classified as healthy (n = 56), CM (n = 62), and CHF (n = 44). The minimal LA:Ao (LA:Ao_min) and minimal LAV from the left apical view (LAV_min-LAP) best differentiated the CM and CHF groups. The LA:Ao_min value with the optimal sensitivity and specificity to distinguish CM and CHF cats was 1.64 (sensitivity 84% and specificity 75%).

CONCLUSIONS

Left atrial volumes were not superior to linear measurements of LA size in distinguishing CM and CHF cats in this study. Minimal LA size and volumes resulted in a larger area under the curve than each corresponding maximal value. Minimum LA size may be a better prognostic factor of CHF in cats with CM.

Evaluation of a sensitive cardiac troponin I assay as a screening test for the diagnosis of hypertrophic cardiomyopathy in cats

Background

Hypertrophic cardiomyopathy (HCM) is the most common cardiac disease in cats. However, most cats are not diagnosed until they develop congestive heart failure, arterial thromboembolism (ATE), or sudden cardiac death. Thus, an affordable screening test for early detection of HCM is desirable.

Hypothesis/Objectives

Evaluation of a sensitive cardiac troponin I (cTnI) assay as a screening test for HCM in cats and determination of a cutoff for its early detection.

Animals

One hundred sixty‐six client‐owned cats (male, n = 97) of various breeds were evaluated and classified using echocardiography as being healthy (n = 87), equivocal (n = 15), or having HCM (mild, n = 16; moderate, n = 10; severe, n = 34) or ATE (n = 4).

Methods

All cats were prospectively evaluated by echocardiography, and serum cTnI concentration was determined using the currently most sensitive assay (Siemens ADVIA Centaur TnI‐Ultra).

Results

The median cTnI concentration was significantly different between study groups (P < .000001). A cutoff of 0.06 ng/mL provided good discrimination between healthy cats and cats with HCM (sensitivity, 91.7%; specificity, 95.4%; area under the curve [AUC], 0.95; 95% confidence interval [CI], 0.899‐0.978). Even for asymptomatic cats with HCM, sensitivity and specificity for a cutoff of >0.06 ng/mL remained high at 87.8% and 95.4%, respectively (AUC, 0.93; 95% CI, 0.864‐0.964).

Conclusions and clinical importance

Cardiac troponin I can be used as a sensitive and specific screening test for the diagnosis of HCM in otherwise healthy cats (cutoff, >0.06 ng/mL). However, echocardiography is needed to confirm the diagnosis.

Feline Hypertrophic Cardiomyopathy: The Consequence of Cardiomyocyte-Initiated and Macrophage-Driven Remodeling Processes?

vHypertrophic cardiomyopathy (HCM) is the most commonly diagnosed cardiac disease in cats. The complex pathophysiology of HCM is still far from clear, but myocardial remodeling is a key process, and cardiomyocyte disarray, interstitial fibrosis, leukocyte infiltration, and vascular dysplasia are described histopathologic features. The present study systematically investigated the pathological processes in HCM, with the aim to shed more light on its pathogenesis. Hearts from 18 HCM cases and 18 cats without cardiac disease (controls) were examined, using light and transmission electron microscopy, immunohistochemistry, and morphometric approaches to identify and quantify the morphological changes. Reverse transcription-quantitative polymerase chain reaction was applied to provide additional mechanistic data on remodeling processes. In HCM, the left and right ventricular free wall and septal myocardium exhibited a significantly reduced overall cellularity, accompanied by a significant increase in interstitial Iba1-positive cells with macrophage morphology. In addition, the myocardium of almost half of the diseased hearts exhibited areas where cardiomyocytes were replaced by cell-rich fibrous tissue with abundant small and medium-sized vessels. HCM hearts also showed significantly higher transcription levels for several inflammatory and profibrotic mediators. Our findings suggest that HCM is the consequence of cardiac remodeling processes that are the result of cardiomyocyte damage and to which macrophages contribute by maintaining an inflammatory and profibrotic environment.

Thoracic radiography in the cat: Identification of cardiomegaly and congestive heart failure

Thoracic radiography is one of the most commonly employed diagnostic tools for the clinical evaluation of cats with suspected heart disease and is the standard diagnostic method in the confirmation of cardiogenic pulmonary edema. In the past, interpretation of feline radiographs focused on a description of the qualitative radiographic features of feline heart disease or the measurement of the cardiac silhouette in healthy cats and cats with different cardiovascular disorders. More recently, studies have begun to critically address the issue of the diagnostic accuracy of thoracic radiography in the diagnostic work-up of cats with heart disease. In these studies, qualitative and quantitative radiographic parameters were compared to echocardiographic findings to evaluate the usefulness of thoracic radiography for the identification of cardiac enlargement and pulmonary edema in the cat. Thoracic radiography is reasonably specific but has a low sensitivity when identifying cardiomegaly in cats with mild structural heart disease. Feline cardiogenic pulmonary edema has a variable radiographic presentation and several specific radiographic findings (i.e., enlargement of the left atrium and the pulmonary veins) can be absent or non-recognizable in affected cats.

Screening for hypertrophic cardiomyopathy in cats

Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats, and it can lead to increased morbidity and mortality. Cats are often screened for HCM because of the presence of a heart murmur, but screening for breeding purposes has also become common. These cats are usually purebred cats of breeding age, and generally do not present with severe disease or with any clinical signs. This type of screening is particularly challenging because mild disease may be difficult to differentiate from a normal phenotype, and the margin for error is small, with potentially major consequences for the breeder. This article reviews HCM screening methods, with particular emphasis on echocardiography.

Sequential segmental classification of feline congenital heart disease

Feline congenital heart disease is less commonly encountered in veterinary medicine than acquired feline heart diseases such as cardiomyopathy. Understanding the wide spectrum of congenital cardiovascular disease demands a familiarity with a variety of lesions, occurring both in isolation and in combination, along with an appreciation of complex nomenclature and variable classification schemes. This review begins with an overview of congenital heart disease in the cat, including proposed etiologies and prevalence, examination approaches, and principles of therapy. Specific congenital defects are presented and organized by a sequential segmental classification with respect to their morphologic lesions. Highlights of diagnosis, treatment options, and prognosis are offered. It is hoped that this review will provide a framework for approaching congenital heart disease in the cat, and more broadly in other animal species based on the sequential segmental approach, which represents an adaptation of the common methodology used in children and adults with congenital heart disease.

Hypovolemia induced systolic anterior motion of the mitral valve in two dogs

Systolic anterior (septal) motion of the mitral valve (SAM) is a common secondary phenomenon in hypertrophic cardiomyopathy (HCM) in people and cats. In humans, it is increasingly recognized that SAM may be found in other cardiac and non-cardiac disease states. In small animal cardiology, SAM unassociated with HCM has been described in dogs with mitral valve dysplasia and right ventricular pressure overload. In this report, we describe two cases of dogs where transient SAM was caused by hypovolemia. When SAM was present both dogs showed pseudohypertrophy and tachycardia. Important factors in the genesis of SAM in this scenario are probably hypovolemia induced changes in left ventricular geometry affecting the orientation of the mitral valve apparatus combined with elevated catecholamine levels. SAM associated with increased wall thickness is not pathognomonic of HCM; this observation is of particular clinical importance when extrapolated to species where HCM is highly prevalent, e.g., cats. An echocardiographic diagnosis should always be evaluated together with full clinical assessment of history and physical examination.

Biologic variability of N-terminal pro-brain natriuretic peptide in adult healthy cats

Objectives The biologic variability of N-terminal pro-brain natriuretic peptide (NT-proBNP) and its impact on diagnostic utility is unknown in healthy cats and those with cardiac disease. The purpose of this study was to determine the biologic variation of NT-proBNP within-day and week-to-week in healthy adult cats. Methods Adult cats were prospectively evaluated by complete blood count (CBC), biochemistry, total thyroxine, echocardiography, electrocardiography and blood pressure, to exclude underlying systemic or cardiac disease. Adult healthy cats were enrolled and blood samples were obtained at 11 time points over a 6 week period (0, 2 h, 4 h, 6 h, 8 h, 10 h and at weeks 2, 3, 4, 5 and 6). The intra-individual (coefficient of variation [CV_I]) biologic variation along with index of individuality and reference change values (RCVs) were calculated. Univariate models were analyzed and included comparison of the six different time points for both daily and weekly samples. This was followed by a Tukey's post-hoc adjustment, with a P value of <0.05 being significant. Results The median daily and weekly CV_I for the population were 13.1% (range 0-28.7%) and 21.2% (range 3.9-68.1%), respectively. The index of individuality was 0.99 and 1 for daily and weekly samples, respectively. The median daily and weekly RCVs for the population were 39.8% (range 17.0-80.5%) and 60.5% (range 20.1-187.8%), respectively. Conclusions and relevance This study demonstrates high individual variability for NT-proBNP concentrations in a population of adult healthy cats. Further research is warranted to evaluate NT-proBNP variability, particularly how serial measurements of NT-proBNP may be used in the diagnosis and management of cats with cardiac disease.

[Restrictive ventricular septal defect in a dwarf rabbit]

A 9-week-old intact female dwarf rabbit was presented for evaluation of a heart murmur. Physical examination revealed a grade IV/VI systolic heart murmur with the maximal intensity over the right heart base. Evidence for a left-sided cardiomegaly was present on lateral and dorsoventral radiographs. An electrocardiogram was recorded in right lateral recumbency, which revealed a sinus tachycardia with a heart rate of 360 beats/minute. Echocardiography showed normal dimensions for the atria and ventricles. Two-dimensional echocardiography confirmed the presence of a perimembranous ventricular septal defect (VSD) with a diameter of 0.8 mm. Identification of the VSD was possible from a right (long and short axes) and a left parasternal window. Peak flow velocity of the systolic left to right shunt was 5.2 m/s. Additionally, a relative pulmonic stenosis (peak flow in the pulmonary artery of 1.02 m/s, pulsed-wave Doppler) was present. According to these findings, the VSD was classified as restrictive. At this time point, medical treatment was unnecessary. The re-examination after 7 weeks revealed unchanged morphological and haemodynamic findings. The VSD in this dwarf rabbit displayed both in the physical and echocardiographic examinations typical features as seen in dogs and cats as well as in one New Zealand white rabbit.

Cardiovascular-renal axis disorders in the domestic dog and cat: a veterinary consensus statement

OBJECTIVES

There is a growing understanding of the complexity of interplay between renal and cardiovascular systems in both health and disease. The medical profession has adopted the term "cardiorenal syndrome" (CRS) to describe the pathophysiological relationship between the kidney and heart in disease. CRS has yet to be formally defined and described by the veterinary profession and its existence and importance in dogs and cats warrant investigation. The CRS Consensus Group, comprising nine veterinary cardiologists and seven nephrologists from Europe and North America, sought to achieve consensus around the definition, pathophysiology, diagnosis and management of dogs and cats with "cardiovascular-renal disorders" (CvRD). To this end, the Delphi formal methodology for defining/building consensus and defining guidelines was utilised.

METHODS

Following a literature review, 13 candidate statements regarding CvRD in dogs and cats were tested for consensus, using a modified Delphi method. As a new area of interest, well-designed studies, specific to CRS/CvRD, are lacking, particularly in dogs and cats. Hence, while scientific justification of all the recommendations was sought and used when available, recommendations were largely reliant on theory, expert opinion, small clinical studies and extrapolation from data derived from other species.

RESULTS

Of the 13 statements, 11 achieved consensus and 2 did not. The modified Delphi approach worked well to achieve consensus in an objective manner and to develop initial guidelines for CvRD.

DISCUSSION

The resultant manuscript describes consensus statements for the definition, classification, diagnosis and management strategies for veterinary patients with CvRD, with an emphasis on the pathological interplay between the two organ systems. By formulating consensus statements regarding CvRD in veterinary medicine, the authors hope to stimulate interest in and advancement of the understanding and management of CvRD in dogs and cats. The use of a formalised method for consensus and guideline development should be considered for other topics in veterinary medicine.

Anatomopathological staging of feline hypertrophic cardiomyopathy through quantitative evaluation based on morphometric and histopathological data

Diagnosis of feline hypertrophic cardiomyopathy (HCM) is both clinical and anatomopathological. Since standardized echocardiographic parameters have previously been established for its diagnosis and classification, the aim of the present study is to provide an original, complete and repeatable quantitative anatomopathological evaluation of this myocardial disease. Since ES-HCM is a clearly defined clinicopathological entity of feline HCM, the present study also aims to investigate its temporal evolution. The hearts of 21 cats with previous diagnosis or suspicion of HCM and 6 control animals were submitted for morphometric and histopathological investigations. The proposed quantitative assessment of gross and histopathological features of HCM appears to be original and repeatable. Correlations between morphometric data allow to establish that the progression to the end-stage phenotypes, primarily characterized by increase in left ventricular fibrous tissue deposition, is accompanied by dilation of left ventricular lumen (P=0.0004) and left atrium (P=0.0017) and increase in intramural coronary arteriosclerosis (P=0.0293).

Impaired cardiac mitochondrial oxidative phosphorylation and enhanced mitochondrial oxidative stress in feline hypertrophic cardiomyopathy

Mitochondrial dysfunction and oxidative stress are important players in the development of various cardiovascular diseases, but their roles in hypertrophic cardiomyopathy (HCM) remain unknown. We examined whether mitochondrial oxidative phosphorylation (OXPHOS) capacity was impaired with enhanced mitochondrial oxidative stress in HCM. Cardiac and skeletal muscles were obtained from 9 domestic cats with spontaneously occurring HCM with preserved left ventricular systolic function and from 15 age-matched control cats. Mitochondrial OXPHOS capacities with nonfatty acid and fatty acid substrates in permeabilized fibers and isolated mitochondria were assessed using high-resolution respirometry. ROS release originating from isolated mitochondria was assessed by spectrofluorometry. Thiobarbituric acid-reactive substances were also measured as a marker of oxidative damage. Mitochondrial ADP-stimulated state 3 respiration with complex I-linked nonfatty acid substrates and with fatty acid substrates, respectively, was significantly lower in the hearts of HCM cats compared with control cats. Mitochondrial ROS release during state 3 with complex I-linked substrates and thiobarbituric acid-reactive substances in the heart were significantly increased in cats with HCM. In contrast, there were no significant differences in mitochondrial OXPHOS capacity, mitochondrial ROS release, and oxidative damage in skeletal muscle between groups. Mitochondrial OXPHOS capacity with both nonfatty acid substrates and fatty acid substrates was impaired with increased mitochondrial ROS release in the feline HCM heart. These findings provide new insights into the pathophysiology of HCM and support the hypothesis that restoration of the redox state in the mitochondria is beneficial in the treatment of HCM.

Case-control study of the effects of pimobendan on survival time in cats with hypertrophic cardiomyopathy and congestive heart failure

OBJECTIVE

To assess survival time and adverse events related to the administration of pimobendan to cats with congestive heart failure (CHF) secondary to hypertrophic cardiomyopathy (HCM) or hypertrophic obstructive cardiomyopathy (HOCM).

DESIGN

Retrospective case-control study.

ANIMALS

27 cats receiving treatment with pimobendan and 27 cats receiving treatment without pimobendan.

PROCEDURES

Medical records between 2003 and 2013 were reviewed. All cats with HCM or HOCM treated with a regimen that included pimobendan (case cats) were identified. Control cats (cats with CHF treated during the same period with a regimen that did not include pimobendan) were selected by matching to case cats on the basis of age, sex, body weight, type of cardiomyopathy, and manifestation of CHF. Data collected included signalment, physical examination findings, echocardiographic data, serum biochemical values, and survival time from initial diagnosis of CHF. Kaplan-Meier survival curves were constructed and compared by means of a log rank test.

RESULTS

Cats receiving pimobendan had a significant benefit in survival time. Median survival time of case cats receiving pimobendan was 626 days, whereas median survival time for control cats not receiving pimobendan was 103 days. No significant differences were detected for any other variable.

CONCLUSIONS AND CLINICAL RELEVANCE

The addition of pimobendan to traditional treatment for CHF may provide a substantial clinical benefit in survival time for HCM-affected cats with CHF and possibly HOCM-affected cats with CHF.

Diagnostic accuracy of the vertebral heart score and other radiographic indices in the detection of cardiac enlargement in cats with different cardiac disorders

A retrospective search was conducted to evaluate the diagnostic accuracy of the vertebral heart score (VHS) and other related radiographic indices in the detection of cardiac enlargement associated with different cardiac disorders in the cat. One hundred and five cats with a complete echocardiographic examination and radiographic examination of the thorax with at least two orthogonal views were enrolled. Eighty-three cats had different cardiac disorders, 72 with left-sided cardiac disorders (LSCD) and 11 with right-sided cardiac disorders; 22 cats were free of cardiovascular abnormalities. Measurements of VHS and cardiac long and short axes on lateral (L) and dorsoventral or ventrodorsal radiographs were obtained. Receiver operating characteristic curves were calculated to evaluate the diagnostic accuracy of each radiographic index in differentiating between cats with cardiac disorders or cats with LSCD and cats without cardiac abnormalities and, among cats with LSCD, between those with no or mild left atrial enlargement (LAE) or those with moderate-to-severe LAE and healthy cats. The L-VHS at the cut-off of 7.9 had high diagnostic accuracy in distinguishing cats with LSCD and moderate-to-severe LAE from healthy cats, but all the other radiographic indices were moderately accurate in distinguishing between cats with overall cardiac disorders or LSCD, either with no or mild LAE and moderate-to-severe LAE, and healthy cats. The considered radiographic indices were also moderately accurate in predicting different degrees of LAE in cats with LSCD. Radiographic indices are reasonably specific, but less sensitive predictors of cardiac enlargement in cats with heart disorders.

Diagnostic value of morphometry in feline hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common form of feline heart disease. To date, reliable morphometric reference data for anatomical or histological changes are unavailable. The aim of this study was to identify diagnostically relevant morphometric criteria that clearly distinguish feline HCM from normal hearts. Hearts from 15 cats with HCM had increased weights (g per distance between the first and eighth vertebral bodies) when compared with hearts from 15 matched control cats. Several anatomically defined and digitally scanned areas of standardized cross sections were significantly increased in HCM when compared with controls, including the area across the entire heart half-way between the coronary sulcus and apex, the right and left ventricular walls and the ventricular septum. Differences were similar when the papillary muscles were included in the measurements of the right and left ventricular walls and the ventricular septum. Histological morphometric analyses failed to identify any significant differences, including the diameter and cross-sectional area of cardiomyocytes and the length, width or areas of cross-sectioned nuclei. In addition, morphometric analyses failed to identify any differences in the amount of cardiomyocyte fibre branching or myocardial fibrosis. Thus, only the relative weight and macroscopical analyses proved useful in distinguishing feline hearts with HCM from normal hearts. The results do not uphold the hypothesis that increased cardiomyocyte diameter is a principal change in feline HCM.

Hypertrophic cardiomyopathy in the Sphynx cat: a retrospective evaluation of clinical presentation and heritable etiology

Hypertrophic cardiomyopathy is an inherited disease in some feline breeds including the Maine Coon and Ragdoll. In these breeds, distinct causative genetic mutations have been identified. The two breeds appear to have slightly different clinical presentations, including age of diagnosis. The observation that these two breeds may have different clinical presentations, as well as different genetic mutations, suggests that hypertrophic cardiomyopathy is a diverse disease in the cat. Hypertrophic cardiomyopathy is poorly described in the Sphynx. The objective of this study was to phenotypically characterize Sphynx hypertrophic cardiomyopathy and to evaluate for a familial etiology. Records of 18 affected cats (11 female, seven male) were evaluated. Age of affected cats ranged from 0.5 to 7 years (median, 2 years). Four affected cats were from a single family and included an affected cat in each of four generations (three females, one male). Further studies are warranted to evaluate for a causative mutation and better classify the phenotypic expression.

Comparison of auscultatory and echocardiographic findings in healthy adult cats

OBJECTIVES

This pilot study was performed to investigate murmur prevalence and to explore the association between auscultatory and echocardiographic findings in apparently healthy cats in order to design a larger study.

ANIMALS, MATERIALS AND METHODS

Adult cats in 4 rehoming centres were screened by auscultation and echocardiography (echo) over 2 periods of 2 weeks each. In the first period, echo was attempted only in cats with murmurs. In the second period, all cats underwent auscultation by 2 observers and echo. LVH was defined in 5 ways: maximal diastolic left ventricular (LV) wall thickness ≥ 6 mm or ≥ 5.5 mm with 2D (LVH(6 2D), LVH(5.5 2D), respectively) or M-Mode echo (LVH(6 MM) or LVH(5.5 MM) respectively), or LV wall thickness ≥ 6 mm (2D) for >50% of a wall segment (LVH(50%)).

RESULTS

67/199 (34%) cats had a murmur. Interobserver agreement on murmur presence was moderate (κ 0.47). 61 cats with a murmur and 31 cats without underwent both auscultation and echo. Depending on the criteria, LVH was present in 31 (LVH(6 2D)), 21 (LVH(50%)) and 11 (LVH(6 MM)) scanned cats. 18-62% of cats with murmurs had LVH, depending on the echo criteria used. Agreement was best between observers in identifying LVH using LVH(6 2D) and LVH(50%) (κ = 1.0).

CONCLUSIONS

Heart murmurs are common in apparently healthy cats. The prevalence of LVH varies depending on the criteria used.