Cause of heart murmurs in 57 apparently healthy cats

Heart murmurs are caused by turbulent blood flow or by vibration of cardiac structures. Turbulent blood flow may originate from structural heart disease or from physiological phenomena. The aims of this study were to establish the cause of heart murmurs in apparently healthy adult cats and to determine whether a heart murmur is a reliable indicator of heart disease. In this retrospective study, we reviewed the medical records of cats in which a heart murmur was detected during physical examination by one of the authors in the period January 2008 to December 2009. Cats younger than 6 months and those with systemic disease were excluded. Timing, grade, and point of maximum intensity of the murmur were determined by one observer (MD) before 2D-, M-mode and Doppler echocardiography. Fifty-seven cats (median age 76 months, range 6-194) were included, 30 neutered females and 27 neutered males. All murmurs were systolic and varied in intensity from 2/6 to 5/6. The point of maximum intensity was the left or right parasternal region in 34/57 (61%) of murmurs. Murmurs were caused by dynamic left ventricular outflow tract obstruction in 25/57 (44%) cats, dynamic right ventricular outflow tract obstruction in 9/57 (16%) cats, and combined dynamic left and right outflow tract obstruction in 11/57 (19%) cats. In 5 (9%) cats the cause of the murmur could not be identified. Heart disease was present in 50 (88%) cats, namely, left ventricular hypertrophy in 44 (77%) and congenital defects in 6 (11%) cats. In conclusion, most heart murmurs in apparently healthy cats are detected in the left or right parasternal region and are caused by dynamic left and right ventricular outflow tract obstruction. Because most cats (88%) with a heart murmur had heart disease in this study, if a heart murmur is detected in an apparently healthy cat, echocardiography is recommended to determine the cause of the heart murmur and the presence of heart disease.     

Estimated prevalence of polysaccharide storage myopathy among overtly healthy Quarter Horses in the United States

OBJECTIVE: To estimate the prevalence of polysaccharide storage myopathy (PSSM) among Quarter Horses in the United States and evaluate possible relationships between muscle glycogen concentration, turnout time, and exercise level. DESIGN: Cross-sectional study. ANIMALS: 164 overtly healthy Quarter Horses > 2 years old from 5 states. PROCEDURES: Horses with a history of exertional rhabdomyolysis or any other muscular disease were excluded. Muscle biopsy specimens were examined histologically for evidence of PSSM and were submitted for determination of muscle glycogen concentration. A diagnosis of PSSM was made if amylase-resistant inclusions that stained with periodic acid-Schiff stain were detected. RESULTS: Prevalences of PSSM on the 2 farms with a history of PSSM were 20% (1/5) and 40.7% (11/27); mean prevalence for the other 4 farms was 6.1% (8/132). Sex was not significantly associated with a diagnosis of PSSM, and age was not significantly different between horses with and without PSSM. Total histologic score, serum creatine kinase activity, and muscle glycogen concentration were significantly higher in horses with PSSM than in horses without. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the prevalence of PSSM among overtly healthy Quarter Horses in the United States is likely to be between 6% and 12%.     

Echocardiographic ratio indices in overtly healthy Boxer dogs screened for heart disease

BACKGROUND: Boxer dogs are routinely screened by echocardiography to exclude congenital and acquired heart disease. Individuals of a given breed may span a large range of body sizes, potentially invalidating linear regression of M-mode measurements against body weight. Echocardiographic ratio indices (ERIs) provide a novel method of characterizing echocardiographic differences between Boxers and other dog breeds. HYPOTHESIS: ERIs obtained from overtly healthy Boxer dogs presented for cardiac screening will be different from ERIs established for normal non-Boxer dogs, and those differences will be unrelated to aortic velocity or systolic blood pressure. ANIMALS: Eighty-one Boxers with no outward clinical signs of heart disease were studied. METHODS: All dogs were examined by 2-dimensional, M-mode, and Doppler echocardiography. M-mode measurements were used to perform ERI calculations, and the indices in Boxers were compared between Boxers with varying severity of arrhythmia and those of normal non-Boxer dogs. RESULTS: Differences in weight-based ERIs, which reflect increased thickness of the left ventricular free wall (LVW) and interventricular septum (IVS) and smaller aortic size, were found in overtly healthy Boxer dogs compared with normal non-Boxer dogs. ERIs of left atrial and LV cavity size in overtly healthy Boxers were not significantly different from those of non-Boxer dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: Boxer dogs may have an increased relative thickness of the LVW and IVS that is independent of aortic size, aortic velocity, or arterial blood pressure, and this morphology should be taken into consideration when screening Boxers by echocardiography.     

Prevalence of echocardiographic evidence of cardiac disease in apparently healthy cats with murmurs

The objective of this prospective study was to determine the prevalence of echocardiographic evidence of heart disease in apparently healthy cats with heart murmurs. Thirty-two privately owned domestic cats were examined. All cats were considered healthy on the basis of history and physical examination, except for the finding of a heart murmur on auscultation. Cats on any medications (besides regular flea, tick and heartworm preventative) or that were pregnant or lactating were excluded from this study. The prevalence of echocardiographic evidence of heart disease in this population of cats was 53%. Therefore, identification of a heart murmur on routine physical examination in apparently healthy cats warrants further investigation.     

Feline respiratory viruses—their prevalence in clinically healthy cats

The prevalence of feline calicivirus (FGV) and feline viral rhinotracheitis (FVR) virus was assessed in three different groups of clinically healthy domestic cats. The 1500 cats were sampled using single oro-pharyngeal swabs. The rate of isolation for FCV and FVR virus respectively was 8% and 1% in the household pet sample, 24·02% and 1·75% in the cat-show sample and 41·5% and 0·4% in colonies A and B. The differences are discussed in relation to the different carrier states of these viruses and the social habits of the cats in each group. A computer analysis of the cat-show group with regard to age, sex and breed demonstrated a statistically significant, lower infection rate of FCV in (1) neutered animals as compared with entires, (2) older cats compared with 0–1 year old animals and (3) certain age groups in both the Longhaired and Burmese cats as compared with other breeds. Résumé. On a évalué la fréquence de virus calice félin et de virus rhinotrachéite viral félin dans les différents groupes de chats domestiques cliniquement en bonne santé. On a essayé un seul prélèvement oropharyngien dans 1500 chats. Le pourcentage d'isolation pour le virus FCV et le virus FVR était respectivement de 8% te de 1% dans l'échantillon de prélèvement du chat domestique, 24,02% et 1,75% dans l'échantillon du chat d'exposition et de 41,5% et de 0,4% dans les colonies A et B. On discute des différences en relation avec les différents états des porteurs de ces virus et des habitudes sociales des chats dans chaque groupe. Une analyse par machine à calculer électronique du chat d'exposition concernant l'âge, le sexe et la race a démontré un pourcentage statistiquement significatif plus faible d'infection de FCV chez (1) des animaux châtrés comparés â des animaux non-châtrés, (2) des chats plus âgés comparés à des animaux de 0 à 1 an et (3) des groupes d'une certaine classe chez des chats à poils longs et des chats de Birmanie en comparaison avec d'autres races. Zusammenfassung. Das Vorherrschen von Katzen-Kalizivirus (FCV) und Katzen-virusalen Rhinotracheitis (FVR) Virus wurden in den verschiedenen Gruppen von klinisch gesunden Hauskatzen geschächtzt. Die 1500 Katzen wurden geprüft indem man einem einzigen Mundrach-enabstrich machte. Das Verhàltnis von Isolierung für FCV und FVR Virus war jeweilig 8% und 1% in der Hauskatzenprobe, 24,02% und 1,75% in der Katzenschauprobe und 41,5% und 0,4% in den Kolonien A und B. Die Unterschiede werden diskutiert in bezug auf den verschiedenen Übertragungszustand von diesen Viren und den geselligen Angewohnheiten dieser Katzen in jeder Gruppe. Eine Komputeranalyse der Katzenschaugruppe in bezug auf Alter, Geschlecht und Rasse bewies eine statistisch bedeutsame, niederere Infektionsrate an FCV in (1) kastrierten Tieren als der verglichen mit Nichtkastrierten, (2) ältere Katzen verglichen mit 0–1 jährig alten Tieren und (3) gewisse Altersgruppen bei den langhaarig- und Burmesischen Katzen verglichen mit anderen Rassen.     

Radiographic measurement of vertebral heart size in healthy stray cats

The aims of this study were to determine vertebral heart size (VHS) in stray cats and to compare different radiographic views. This study was performed on 50 adult stray cats. All cats were short-haired and non-obese and were considered to be healthy based on physical examination and electrocardiography. Left and right lateral, dorsoventral and ventrodorsal radiographs were taken. The long and short axes of the heart were measured in millimetres. The thoracic vertebral length spanned by each dimension was measured caudally from the fourth thoracic vertebra. Mean+/-SD and the correlation coefficient between the measurements were calculated with standard statistical software. The sum of the long and short axes of the heart expressed as VHS was 7.3+/-0.49 vertebrae in right lateral, 7.3+/-0.55 vertebrae in left lateral, 7.5+/-0.68 vertebrae in dorsoventral and 7.5+/-0.53 vertebrae in ventrodorsal. The differences between right and left lateral as well as dorsoventral and ventrodorsal views were not significant (P>0.05). Absolute measurements and vertebral heart scale values were slightly smaller than those reported in the literature for mixed population of cats. It is, therefore, important to take the breed in to account.     

Evaluation of plasma C-terminal atrial natriuretic peptide in healthy cats and cats with heart disease

BACKGROUND: The clinical implications of evaluating C-terminal atrial natriuretic peptide (ANP) concentration in cats are still controversial. HYPOTHESIS: The objective of this study was to investigate the relationship between plasma C-terminal ANP concentration and left atrial pressure (LAP) in healthy cats with volume overload (study 1), and to compare plasma C-terminal ANP in normal cats and cats with cardiomyopathy (study 2). ANIMALS: Five healthy adult cats were used in study 1, and clinically healthy cats (n=8) and cats with cardiomyopathy (n=14) were used in study 2. METHODS: In study 1, cats were anesthetized and given acetated Ringer's solution (100 mL/kg/h for 60 minute) via the cephalic vein. Hemodynamic measurements and blood samples, collected from the jugular vein, were performed at 10-min intervals. In study 2, blood samples from normal cats and cats with cardiomyopathy were collected from the cephalic vein. The plasma C-terminal ANP concentration was determined by radioimmunoassay for human alpha-ANP. RESULTS: In study 1, volume overload significantly increased the C-terminal ANP concentration and LAP from baseline. The C-terminal ANP concentration was strongly correlated with the mean LAP. In study 2, age, E wave velocity, and the ratios of the left atrium to aorta were significantly higher in the cats with cardiomyopathy compared with the normal cats. The C-terminal ANP concentration was significantly higher in the cats with cardiomyopathy compared with the normal cats. CONCLUSIONS AND CLINICAL IMPORTANCE: Our results suggest that the measurement of plasma C-terminal ANP in cats may provide additional information for the diagnosis of heart disease.     

Results of ambulatory electrocardiography in overtly healthy Doberman Pinschers with echocardiographic abnormalities

OBJECTIVE: To identify, by means of 24-hour ambulatory electrocardiography, electrocardiographic abnormalities in overtly healthy Doberman Pinschers in which results of echocardiography were abnormal. DESIGN: Clinical case series. ANIMALS: 56 (35 male, 21 female) overtly healthy Doberman Pinschers with echocardiographic evidence of cardiomyopathy on initial examination that subsequently died of cardiomyopathy. PROCEDURE: Twenty-four-hour ambulatory electrocardiographic (Holter) recordings obtained at the time of initial examination were reviewed. For all dogs, scan quality was > 90%. RESULTS: Initial Holter recordings of all 56 dogs contained ventricular premature contractions (VPC). Thirty-six (65%) dogs had > 1,000 VPC/24 h, 17 (31%) had > 5,000 VPC/24 h, and 11 (19%) had > 10,000 VPC/24 h. Fifty-four (96%) dogs had couplets of VPC, 37 (66%) had triplets of VPC, and 36 (64%) had episodes of nonsustained (< 30 seconds) ventricular tachycardia. Number of VPC/24 h during the initial Holter recordings was positively correlated with numbers of couplets and triplets of VPC and number of ventricular escape beats and negatively correlated with left ventricular fractional shortening. Twenty-eight dogs died suddenly prior to the putative onset of congestive heart failure. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that along with echocardiography, 24-hour ambulatory electrocardiography can be used to help identify overtly healthy Doberman Pinschers with cardiomyopathy.     

Abnormal heart sounds and murmurs of the dog

Abstract— —In addition to physiological murmurs as found in association with fever and anemia, a number of organic murmurs resulting from cardiac lesions frequently occur in dogs. These include the pansystolic regurgitant murmur of mitral and tricuspid insufficiency and interventricular septal defect, the ejection systolic murmur of aortic and pulmonic stenosis and the continuous murmur of patent ductus arteriosus. The arterial diastolic murmur of aortic insufficiency occurs less frequently; that of pulmonic insufficiency is even less often encountered. The passive atrioventricular diastolic murmurs and atriosystolic murmurs of relative or absolute mitral or tricuspid stenosis are extremely rare. The most frequently heard abnormal transients in the dog are the ventricular diastolic gallop, the systolic click, and the presystolic atrial gallop. Splitting of the second heart sound is a fairly common finding in areas where heartworm heart disease is prevalent. Paradoxical splitting of S₂ is only occasionally observed. Résumé— —En surcoit des souffles physiologiques comme constatés en association à la fiévre et l'anémie, de nombreux souffles organiques résultant de lésions cardiaquessurvenant fréquemment chez le chien. Ceux-ci comprennent le souffle pansystolique régurgitant d'insuffisance mitrale et tricuspide et de défaut de la cloison interventriculaire, le souffle d'éjection systolique de retricissement aortique et pulmonaire et le souffle continuel patent du canal arteriosus. Le souffle arteriel diastolique de l'insuffisance aortique se présente moins fréquemment; celui de l'insuffisance pulmonaire survient encour moins souvent. Les souffles passifs atrioventriculaires diastoliques et les souffles atriosystoliques de retrecissement relatifs ou obsolus mitral ou tricuspide sont extrêmement rares. Les transitions anormalies les plus souvent survenues chez le chien sont le galop ventriculaire diastolique, le clic systolique, et le galop artériel presystolique. La séparation du son du second coeur et assez commune dans les régions ou les maladies cardiaques prévalent. La séparation paradoxale de S est occasionnellement observée. Zusammenfassung— —Ausser physiologischen Geraeuschen in Verbindung mit Fieber und Anaemic treten eine Anzahl von organischen Geraeuschen als Resultat von Herzstoerungen haeufig bei Hunden auf. Diese umfassen das pansystolische rueckfliessende Geraeusch der mitralen und trik-uspidalen Insuffizienz und des interventrikularen Septum-Defekts, das Ejektions-systolische Geraeusch der Aorten- und Pulmonal-Stenose und das Dauer-Geraeusch des offenen Duktus arteriosus. Das arterielle diastolische Geraeusch der Aorten-Insuffizienz tritt weniger haeufig auf, das der Pulmonal-Insuffizienz noch seltener. Die passiven atrioventrikulaeren diastolischen Geraeusche und atrio-systolischen Geraeusche der relativen oder absoluten mitralen oder trikuspidalen Stenose sind ausserordentlich selten. Die am haeufigsten gehoerten anormalen vorueber-gehenden Geraeusche beim Hund sind der ventrikulaere diastolische Galopp-Rhythmus, das systolische Einschnappen und der praesystolische atriale Galopp-Rhythmus. Spaltung des zweiten Herztones ist eine ziemlich haeufiger Befund in Gegenden, wo die Herzwurm-Krankheit haeufig ist. Paradoxe Spaltung des zweiten Tones wird nur gelegentlich beobachtet.     

Prevalence and clinical importance of heart murmurs in racehorses

OBJECTIVE: To determine the prevalence of various types of heart murmurs in Thoroughbred racehorses and assess their association with performance by echocardiography and review of the horses' race records for the preceding 2 years. DESIGN: Clinical and retrospective study. ANIMALS: 846 Thoroughbred racehorses. PROCEDURE: Cardiac auscultations were performed by 3 individuals; for 30 horses, Doppler echocardiographic examinations were also performed. Statistical analyses of race records for 753 horses were performed to assess association of heart murmurs with performance. RESULTS: Heart murmurs were detected by cardiac auscultation in 686 of 846 (81.1%) horses. Systolic murmurs over the heart base were most common; 365 (43.1%) horses had systolic murmurs that were loudest over the pulmonary valve area, and 232 (27.4%) horses had systolic murmurs that were loudest over the aortic valve area. Systolic murmurs over the tricuspid valve area were detected in 241 (28.5%) horses, whereas systolic murmurs over the mitral valve area were detected in only 32 (3.8%) horses. Diastolic murmurs were much less common than systolic murmurs. Review of race records did not reveal a significant association between murmurs and performance. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that heart murmurs are a common finding in racehorses; most of these heart murmurs do not appear to be clinically important.     

Renal ultrasonography in healthy cats

Serial ultrasonographic examinations were performed on the kidneys of 10 healthy cats during normal hydration and after administration of contrast medium. Differences in the appearance of anatomic structures or in the echo intensity were not detected between kidneys during normal hydration and after contrast medium administration. The appearance of scanning images was influenced by mode, frequency, and focal range of the transducer, topography and mobility of the kidneys, and adequate sound conduction.     

Heart rate and heart rate variability of healthy cats in home and hospital environments

To investigate heart rate and its variability, a telemetry device was affixed to 16 healthy, young cats. Prior to inclusion in the study, cats were subject to echocardiographic examination. The heart rate (HR) when cats were restrained for echocardiography (HR(r)) was calculated from 4-5 consecutive RR intervals obtained from a simultaneously recorded electrocardiogram. Electrocardiographic data were then acquired by telemetry in a quiet room in the veterinary hospital (VTH) and later, in the owner's home (home). The ambulatory data were digitally sampled and the RR interval tachogram from a 4 min epoch subject to Fast Fourier Transform to yield measures of heart rate variability (HRV). Sinus arrhythmia was often observed in resting cats. Heart rates (bpm) expressed as mean (+/-SD) were: HRr: 187 (+/-25), HRVTH: 150 (+/-23), HR(home): 132 (+/-19); each of these rates was significantly different from the others. Significant differences in profiles of HRV suggested that sympathetic tone was higher (and parasympathetic tone lower) when cats were in the hospital.     

Pharmacokinetics of cetirizine in healthy cats

OBJECTIVE: To develop a high-performance liquid chromatography (HPLC) assay for cetirizine in feline plasma and determine the pharmacokinetics of cetirizine in healthy cats after oral administration of a single dose (5 mg) of cetirizine dihydrochloride. ANIMALS: 9 healthy cats. PROCEDURES: Heparinized blood samples were collected prior to and 0.5, 1, 2, 4, 6, 8, 10, and 24 hours after oral administration of 5 mg of cetirizine dihydrochloride to each cat (dosage range, 0.6 to 1.4 mg/kg). Plasma was harvested and analyzed by reverse-phase HPLC. Plasma concentrations of cetirizine were analyzed with a compartmental pharmacokinetic model. Protein binding was measured by ultrafiltration with a microcentrifugation system. RESULTS: No adverse effects were detected after drug administration in the cats. Mean +/- SD terminal half-life was 10.06 +/- 4.05 hours, and mean peak plasma concentration was 3.30 +/- 1.55 microg/mL. Mean volume of distribution and clearance (per fraction absorbed) were 0.24 +/- 0.09 L/kg and 0.30 +/- 0.09 mL/kg/min, respectively. Mean plasma concentrations were approximately 2.0 microg/mL or higher for 10 hours and were maintained at > 0.72 microg/mL for 24 hours. Protein binding was approximately 88%. CONCLUSIONS AND CLINICAL RELEVANCE: A single dose of cetirizine dihydrochloride (approx 1 mg/kg, which corresponded to approximately 0.87 mg of cetirizine base/kg) was administered orally to cats. It was tolerated well and maintained plasma concentrations higher than those considered effective in humans for 24 hours after dosing. The half-life of cetirizine in cats is compatible with once-daily dosing, and the extent of protein binding is high.     

Pharmacokinetics of ibafloxacin in healthy cats

The pharmacokinetics of ibafloxacin following single and repeated administration of an oral gel formulation and the effect of food intake were investigated in cats. Ibafloxacin is a chiral fluoroquinolone available for clinical use as a racemic mixture of the R- and S-enantiomers. Plasma concentrations of ibafloxacin and its metabolites were determined using microbiological, LC-MS-MS and enantioselective capillary zone electrophoresis assays. Ibafloxacin was absorbed rapidly [time of maximum concentration (tmax) 2-3 h], reaching a mean maximum concentration (Cmax) of approximately 2.1 and 1.6 microg/mL for R- and S-ibafloxacin, respectively, following a single oral administration of the racemate at 15 mg/kg. Once absorbed, ibafloxacin was metabolized to 7-hydroxy-ibafloxacin and mainly to 8-hydroxy-ibafloxacin. Following repeated oral administration, significant increases in Cmax and AUC of ibafloxacin and its less active metabolites (racemic or enantiomers) were observed between the first and the tenth day of treatment. This twofold exposure increase in concentrations of ibafloxacin and its metabolites may contribute additionally to the efficacy of this drug in the treatment of feline bacterial infections. Single and repeated doses of ibafloxacin were well tolerated by cats. Food promoted the absorption of ibafloxacin, doubling Cmax and increasing AUC and slightly delaying tmax. High concentrations of the metabolites, mainly 8-hydroxy- and 7-hydroxy-ibafloxacin were excreted in urine, either unchanged or as glucurono-conjugates.