Isolated discrete upper septal thickening in a non-referral cat population of senior and young cats

INTRODUCTION/OBJECTIVES

Discrete upper septal thickening (DUST) is a phenotype of elderly people. The cardiac phenotype in senior cats has been incompletely described. We aimed to characterize the echocardiographic phenotype of senior cats, specifically to determine prevalence of DUST and hypertrophic cardiomyopathy (HCM).

ANIMALS

One hundred and forty-nine healthy, normotensive cats.

MATERIALS AND METHODS

Prospective cross-sectional study. Senior (≥9 years) and young (<6 years) cats were recruited from non-referral population. We defined DUST as an isolated basilar septal bulge, and HCM as left ventricular wall thickness ≥6 mm. An interventricular septum ratio (basal-to-mid septal thickness ratio) was calculated. We assessed for associations between clinical and echocardiographic variables and DUST. Data are presented as mean (±SD), median (range), or frequency (percentage).

RESULTS

One-hundred and two senior and 47 young cats were enrolled. Aortoseptal angle (AoSA) was steeper in senior cats (137° (±14.5) vs. 145° (±12.3) in young cats, P=0.002). Eighteen cats had DUST (18/149, 12%), fourteen senior, and four young cats (P=0.4). Cats with DUST had steeper AoSA (125° (±8.3) vs. 142° (±13.7), P<0.0001) and higher interventricular septum ratio (1.4 (1.2-2.0) vs. 1.0 (0.7-1.8)). Univariable analysis showed decreased odds of DUST with greater AoSA (OR 0.9, P<0.0001), age was not associated with DUST. Twenty-nine senior cats had HCM (28.4%).

DISCUSSION/CONCLUSIONS

Prevalence of DUST was 12%. There was no association between age and DUST. Smaller/steeper AoSA was the main factor associated with DUST. There was a high prevalence of HCM in this senior population.

Thin and hypokinetic myocardial segments in cats with cardiomyopathy

INTRODUCTION/OBJECTIVES

Thin and hypokinetic myocardial segments (THyMS) represent adverse ventricular (LV) remodeling in human hypertrophic cardiomyopathy. We describe the echocardiographic features and outcome in cats with THyMS, and in a subpopulation, the echocardiographic phenotype before LV wall thinning was detected (pre-THyMS).

ANIMALS

Eighty client-owned cats.

MATERIALS AND METHODS

Retrospective multicenter study. Clinical records were searched for cats with THyMS, defined as LV segment(s) with end-diastolic wall thickness (LVWT) <3 mm and hypokinesis in the presence of ≥one LV segment(s) with LVWT >4 mm and normal wall motion. When available, echocardiograms pre-THyMS were assessed. Survival time was defined as time from first presentation with THyMS to death.

RESULTS

Mean thickest LV wall segment (MaxLVWT) was 6.1 mm (95% CI 5.8-6.4 mm) and thinnest (MinLVWT) was 1.7 mm (95% CI 1.6-1.9 mm). The LV free wall was affected in 74%, apex in 13% and septum in 5%. Most cats (85%) presented with heart failure and/or arterial thromboembolism. Median circulating troponin I concentration was 1.4 ng/mL ([range 0.07-180 ng/mL]). Prior echocardiography results were available for 13/80 cats, a mean of 2.5 years pre-THyMS. In segments subsequently undergoing thinning, initial MaxLVWT measured 6.7 mm (95% CI 5.8-7.7 mm) vs. 1.9 mm (95% CI 1.5-2.4 mm) at last echocardiogram (P<0.0001). Survival data were available for 56/80 cats, median survival time after diagnosing THyMS was 153 days (95% CI 83-223 days). Cardiac histopathology in one cat revealed that THyMS was associated with severe transmural scarring.

CONCLUSIONS

Cats with THyMS had advanced cardiomyopathy and a poor prognosis.

Anterior mitral valve leaflet length in cats with hypertrophic cardiomyopathy

INTRODUCTION

Anterior mitral valve leaflet (AMVL) elongation is a recognised feature of hypertrophic cardiomyopathy (HCM). However, whether AMVL elongation precedes left ventricular hypertrophy in cats is currently unknown. The aim of this study was to explore the risk of developing an HCM phenotype in cats with an elongated AMVL.

ANIMALS

FIFTY-FIVE APPARENTLY HEALTHY CATS WITH A NORMAL BASELINE ECHOCARDIOGRAM AND A FOLLOW-UP ECHOCARDIOGRAM AT >ONE YEAR.

MATERIALS AND METHODS

This was a retrospective longitudinal study. Cats at the baseline were grouped based on whether or not they developed an HCM phenotype at follow-up. AMVL length and left atrial and left ventricular dimensions were measured from two-dimensional images.

RESULTS

The median follow-up period of the study population was 5.4 years (25th and 75th quartile, 2.7-6.7 years). During this time, 17 cats (30.9%) developed an HCM phenotype. At the baseline, cats that subsequently developed an HCM phenotype had greater AMVL length (9.4 mm [25th and 75th quartile, 9.0-10.6 mm] vs. 8.5 mm [25th and 75th quartile, 7.6-9.1 mm], P < 0.0001) and maximal left ventricular wall thickness (4.5 mm [25th and 75th quartile, 4.1-4.7 mm] vs. 4.0 mm [25th and 75th quartile, 3.7-4.6 mm], P = 0.007) than those that did not. Multiple logistic regression analysis confirmed that both baseline variables were independent predictors for development of an HCM phenotype.

CONCLUSIONS

The AMVL length was greater in cats that subsequently developed left ventricular hypertrophy. Further studies investigating the clinical application of AMVL in the natural history of feline HCM are warranted.

Paroxysmal high-grade second-degree and persistent third-degree atrioventricular block in cats

INTRODUCTION

Both paroxysmal high-grade second-degree and persistent third-degree atrioventricular block (AVB) are recognised in cats. Our aim was to document the presentation, echocardiographic data, comorbidities and outcome in affected cats from a single referral hospital, including those that underwent epicardial pacemaker implantation (EPI).

ANIMALS, MATERIALS AND METHODS

This retrospective study included 64 cats diagnosed with persistent third-degree or paroxysmal high-grade AVB, for which detailed patient history was available. Non-parametric testing, Kaplan-Meier curves and Cox proportional hazard testing were performed.

RESULTS

Atrioventricular block was persistent in 43 cats (67%) and paroxysmal in 21 (33%). Forty-seven cats (74%) were referred for cardiac complaints (e.g. collapse, arrhythmia, tachypnea), 6 (9%) had non-specific complaints and AVB was an incidental finding in 11 cats (17%). Median duration of clinical signs prior to presentation was 21 days (1-1138 days). Thirty-nine (63%) cats had echocardiographic abnormalities; 13 (20%) presented with congestive heart failure. Forty-five (70%) cats had one or more comorbidities. Fifteen cats underwent EPI with immediate resolution of signs in 12 cats. Following EPI, two and four cats experienced major and minor complications, respectively. Forty-seven cats died; median survival time was 799 days (all-cause mortality). Cardiac-related death occurred in 17 cats (36%); median survival in these cats was 132 days. Heart failure on presentation was the only independent risk factor for cardiac death (p=0.002).

CONCLUSIONS

Outcome in cats with AVB was variable, although most had good medium- to long-term survival. Cardiac death occurred in a minority of cats. Pacemaker implantation was effective in relieving clinical signs.

Supraventricular tachycardia in 23 cats; comparison with 21 cats with atrial fibrillation (2004-2014)

INTRODUCTION

Supraventricular tachycardia (SVT) has not been well described in cats. The aim of this study was to describe the signalment, clinical findings, and outcome for cats with SVT versus cats with atrial fibrillation (AF).

ANIMALS

Forty-four client owned cats are included in the study. 23 cats with SVT and 21 with AF.

METHODS

This is a retrospective study. Clinical characteristics were compared between groups using a two-sample t-test or Mann-Whitney U test. Kaplan-Meier survival curves were generated to assess for impact of rhythm diagnosis, presence of ventricular arrhythmia, left atrial diameter, heart rate and congestive heart failure (CHF) status on cardiac death. Differences in survival between groups were compared using Mantel-Cox logrank comparison of Kaplan-Meier survival curves.

RESULTS

Cats with supraventricular arrhythmias most commonly presented with respiratory distress (10 of 44 cats). Cats with AF had a slower median heart rate (220 [range: 180-260 beats per minute (bpm)] compared with cats with SVT (300 [range: 150-380] bpm, p < 0.001). All cats with AF had structural heart disease, whereas 4 cats with SVT had no structural abnormalities. Left atrial diameter was significantly larger in cats with AF (23.7 (16.2-40.1) mm compared with 19.1 (12.8-31.4) mm in SVT cats; p = 0.02). Median survival was 58 days (1-780) in cats with AF and 259 days (2-2295) in cats with SVT (p = 0.1). Cats with signs of CHF had a shorter survival time (p = 0.001).

CONCLUSIONS

Most cats with AF or SVT have advanced structural heart disease. Some cats with SVT had structurally normal hearts, suggesting that SVT in cats is not always a consequence of atrial enlargement.

Surgical valvulotomy for tricuspid valve stenosis in a dog

A 2-year, 4-month-old neutered female Labrador retriever was brought for evaluation of right-sided congestive heart failure. Echocardiographic examination revealed tricuspid valve dysplasia with only two small orifices in the valve resulting in severe tricuspid stenosis. The dog underwent a right fifth lateral intercostal thoracotomy and surgical tricuspid valvulotomy, under cardiopulmonary bypass. The stenosis was relieved by dividing the valve leaflets between the two orifices with continuation to the commissures, creating a 'bileaflet' valve. The dog made a good recovery initially, with echocardiography at 48 h after surgery showing a reduction in tricuspid valve E and A wave velocities and pressure half-time (from 230 ms to 65 ms). She was discharged five days after surgery, and spironolactone, benazepril, pimobendan, and clopidogrel were prescribed. The dog was re-presented two days later having collapsed, with pyrexia, facial swelling, and pitting edema on the ventral neck and intermandibular region. Investigations did not reveal an underlying cause, and the clinical signs resolved with supportive therapy. Two years after surgery, the dog was free of clinical signs with normal exercise tolerance and only mild tricuspid regurgitation on echocardiography, with discontinuation of all medications.

Phenotypic description of cardiac findings in a population of Dogue de Bordeaux with an emphasis on atrial fibrillation

The aim of this study was to describe the clinical phenotype of Dogue de Bordeaux (DdB) referred for cardiac investigation, with particular reference to the prevalence of atrial fibrillation and associated features. Review of canine medical records of two United Kingdom veterinary referral hospitals identified 64 DdB with available echocardiographic and electrocardiographic (ECG)/Holter data. Atrial fibrillation was documented in 25 (39%) dogs and supraventricular tachycardia was recorded in five (7.8%) dogs. In a subset of 34 dogs, excluding congenital heart disease (n=17), presence of a cardiac mass (n=7) and non-cardiac neoplasia (n=6), 19 (56%) dogs had atrial fibrillation, with a median heart rate of 200 beats per min (bpm) on presentation. Atrial fibrillation was inconsistently associated with cardiac chamber remodelling, but was frequently associated with systolic dysfunction (13/19, 68.4%) and right sided atrial or ventricular dilatation (14/19, 73.7%) in dogs with atrial fibrillation in this subset. No dogs in this subset had right sided atrial or ventricular dilatation in the absence of supraventricular arrhythmia or systolic dysfunction. The absence of structural heart disease in some dogs with supraventricular arrhythmias suggests that an underlying primary arrhythmic process might be responsible for initiating remodelling, although a primary cardiomyopathy cannot be ruled out.

Transient Myocardial Thickening in Cats Associated with Heart Failure

Background

Cats with hypertrophic cardiomyopathy (HCM) and congestive heart failure (CHF) can have resolution of both left ventricular hypertrophy and CHF.

Objectives

To describe the clinical characteristics of cats with transient myocardial thickening (TMT) and CHF compared with a control population of cats without resolution of HCM.

Animals

A total of 21 cats with TMT, 21 cats with HCM.

Methods

Retrospective study. Clinical records at 4 veterinary centers were searched for TMT cases and a control group of cats with HCM and CHF. TMT was defined as initial maximal left ventricular wall thickness (LVWT) ≥6 mm with left‐sided CHF, with subsequent resolution of CHF, reduction in left atrium/aorta (LA/Ao), and LVWT<5.5 mm. HCM was defined as persistent LVWT ≥6 mm.

Results

Cats with TMT were younger (2 [0.4–11.4] years) than cats with HCM (8 [1.6–14] years) (P < 0.0001), and antecedent events were more common (15/21 versus 6/21, respectively) (P = 0.01). In cats with TMT, LVWT normalized from 6.8 [6.0–9.7] mm to 4.8 [2.8–5.3] mm and LA/Ao decreased from 1.8 [1.6–2.3] to 1.45 [1.2–1.7] after a mean interval of 3.3 (95% CI: 1.8–4.7) months. CHF recurred in 1 of 21 TMT and 15 of 21 cats with HCM. Cardiac treatment was discontinued in 20 of 21 cats with TMT and 0 of 21 HCM cats. All cats with TMT survived, whereas 8 of 19 cats with HCM died during the study period.

Conclusions and Clinical Importance

TMT occurs in younger cats, and antecedent events are common. The prognosis is better in cats with CHF associated with TMT than HCM.

Prevalence and diagnostic characteristics of non-clinical mitral regurgitation murmurs in North American Whippets

OBJECTIVES

To assess the prevalence of functional ejection murmurs and murmurs of mitral regurgitation (MR) due to myxomatous mitral valve disease in healthy whippets; to assess the diagnostic value of auscultation to detect MR; and investigate the relationship between age and presence of echocardiographically documented MR (MR_echo).

ANIMALS

A total of 200 healthy client-owned Whippets, recruited at national shows between 2005 and 2009 were involved in this study.

METHODS

Cross-sectional study. Dogs were examined by auscultation by one examiner and Doppler echocardiography by another, and results were compared. Prevalence of types of murmurs and MR_echo were calculated and correlated to age. Accuracy of auscultation to predict MR_echo was calculated.

RESULTS

Left-sided systolic heart murmurs were detected in 185/200 (93%) of dogs. Left apical systolic murmurs (L_apex) were detected in 57/200 (29%) and left basilar systolic murmurs (L_base) in 128/200 of the dogs (64%). MR_echo was present in 76/200 (38%) dogs. Prevalence MR_echo was correlated with age (r = 0.96, p=0.0028). Mitral regurgitation detected by echocardiography was present in 12/78 (15%) of the dogs ≤ 2 years of age and in 59% of the dogs at 7-8 years old. Detection of L_apex predicted MR_echo with sensitivity 65%, specificity 94%, positive predictive value 86%, and negative predictive value 81%; and accuracy improved when only dogs with more intense L_apex (grade ≥ 3/6) were considered.

CONCLUSIONS

Systolic murmurs are common in North American Whippets and this breed exhibits a high prevalence of MR_echo, which may be documented at a relatively early age. Whippets with non-clinical MR_echo may not be identifiable by auscultation alone; echocardiographic examination may be required to exclude a diagnosis of MR. Louder heart murmurs allow more accurate localization in this population.

Mitral Annular Plane Systolic Excursion and Tricuspid Annular Plane Systolic Excursion in Cats with Hypertrophic Cardiomyopathy

Background

Left ventricular (LV) systolic dysfunction is associated with increased risk of death in cats with hypertrophic cardiomyopathy (HCM). Mitral and tricuspid annular plane systolic excursion (MAPSE and TAPSE, respectively) are measures of longitudinal systolic function and are reduced in human patients with HCM.

Hypotheses

Cats with HCM have lower MAPSE and TAPSE compared to control cats; lower MAPSE and TAPSE are associated with the presence of congestive heart failure (CHF) and reduced survival time.

Animals

64 cats with HCM and 27 healthy cats. Forty‐five cats with HCM were not showing clinical signs, and 19 had CHF.

Methods

Retrospective study. Anatomic M‐mode from the left apical 4‐chamber view was used to record MAPSE from the free wall (MAPSE FW) and septum (MAPSE IVS) and TAPSE.

Results

Compared to controls, cats with HCM had lower MAPSE IVS (controls 5.2 [4.6–5.6] mm, asymptomatic HCM 4.7 [4.1–5.2] mm, HCM with CHF 2.6 [2.5–3.2] mm, P < .001), MAPSE FW (controls 5.9 [5.3–6.2] mm, asymptomatic HCM 4.7 [4.1–5.1] mm, HCM with CHF 2.8 [2.4–3.2] mm) and TAPSE (controls 8.6 [7.4–10.2] mm, asymptomatic HCM 7.2 [6.3–8.2] mm, HCM with CHF 4.6 [4.1–5.4] mm), with the lowest in the CHF group. Univariate survival analysis showed a shorter survival in cats displaying lower MAPSE IVS, MAPSE FW, and TAPSE.

Conclusions and Clinical Importance

MAPSE and TAPSE were lower in cats with HCM than in control cats and were lowest in CHF, suggesting that systolic longitudinal dysfunction is present in cats with HCM. MAPSE and TAPSE have potential prognostic significance.

Blood Pressure Measurements in 780 Apparently Healthy Cats

Background

Mean systolic blood pressure in apparently healthy cats has been reported as approximately 125 mmHg using direct assessment, but there is greater variability in reported values using indirect assessment. Increasing age and the white‐coat effect are associated with increased systolic blood pressure.

Hypothesis/Objectives

To report Doppler‐derived blood pressure measurements from a large population of apparently healthy cats and to assess epidemiologic factors associated with recorded blood pressures.

Animals

A total of 780 cats in rehoming centers enrolled in a screening program for heart murmurs and cardiac disease.

Methods

Cats were considered healthy based on history and physical examination. Cats with known hypertension, hyperthyroidism, or clinical signs of systemic disease and pregnant or nursing queens were excluded. After an acclimatization period, systolic blood pressure was measured using the Doppler sphygmomanometry method following the recommendations of the ACVIM Consensus Statement. General linear model analysis was performed to identify factors associated with variation in systolic blood pressure.

Results

Median (interquartile range, IQR) systolic blood pressure for the group was 120.6 (110.4–132.4) mmHg. Factors significantly associated with higher systolic blood pressure in a general linear model were increased age, increased nervousness, male sex, neutering, or history of being a stray. The model explained 29.2% of the variation in systolic blood pressure.

Conclusions and Clinical Importance

The age, demeanor, sex, neuter status and history of being a stray should be taken into account when assessing systolic blood pressure in apparently healthy cats.

Risk factors associated with sudden death vs. congestive heart failure or arterial thromboembolism in cats with hypertrophic cardiomyopathy

OBJECTIVES

To evaluate risk factors associated with different types of cardiac death in cats with hypertrophic cardiomyopathy (HCM).

ANIMALS

Two hundred fifty-five cats with HCM referred to a veterinary teaching hospital.

METHODS

This is a retrospective study. Cats with HCM were identified that had either died within 2 years of diagnosis or were known to be alive 2 years after initial examination. Signalment, physical exam, electrocardiographic and echocardiographic data were analyzed separately for association with death due to congestive heart failure (CHF) vs. aortic thromboembolism (ATE) vs. sudden death.

RESULTS

Within 2 years of follow-up, 23/255 (9.0%) cats had died with ATE, 44/255 (17.3%) cats had died with CHF and 12/255 (4.7%) cats had experienced a sudden death, with 141/255 (55.3%) cats still alive at the end of 2 years. Presence of CHF at presentation and reduced left ventricular fractional shortening (FS%) were independently associated with a CHF death within 2 years of diagnosis. Presence of ATE and reduced left atrial fractional shortening (LA-FS%) were independently associated with dying with ATE within 2 years. No multivariable models were generated for risks of dying a sudden death owing to the low event rate, but syncope at presentation and arrhythmias on auscultation were associated with sudden death on univariable analysis.

CONCLUSIONS

Asymptomatic cats have a reduced risk of all three types of death. Reduced FS% and a history of CHF independently predict CHF death, and reduced LA-FS% and history of ATE independently predict ATE death. Sudden death is less commonly reported but is associated with syncope.

Cardiac pathology findings in 252 cats presented for necropsy; a comparison of cats with unexpected death versus other deaths

OBJECTIVES

To report necropsy and myocardial histopathology in cats with unexpected death and expected death/euthanasia, comparing findings in 4 groups of cats: unexpected death with noncardiac disease (UD-NC); unexpected death with cardiac disease (UD-C); expected death/euthanasia due to noncardiac disease with incidental cardiac disease (OD + HD); and expected death/euthanasia due to congestive heart failure (CHF).

ANIMALS

Two hundred fifty-two cats undergoing necropsy at a single centre.

METHODS

Signalment, history, body weight, heart weight and myocardial thickness were obtained from medical records. Cardiac histopathology slides were reviewed blindly by a single observer. Data were analysed using a Chi squared, Fisher's exact, Kruskal-Wallis tests or ANOVA as appropriate.

RESULTS

Death at a veterinary clinic and suspected poisoning were the most common reasons for necropsy in 158 cats with an unexpected death. No cause other than cardiac disease was found in 87/158 (55.1%), with hypertrophic cardiomyopathy identified in 68/87 (78%) of UD-C cats. Expected deaths or euthanasia occurred in 27 cats with CHF and 67 cats with concurrent heart disease (OD + HD). Myofiber disarray, interstitial fibrosis, subendocardial fibrosis and intramural arteriolosclerosis were more prevalent in UD-C cats than in UD-NC cats, and subendocardial fibrosis and arteriolosclerosis were more prevalent in UD-C cats than in CHF and OD + HD cats.

CONCLUSIONS

Cardiac disease, and hypertrophic cardiomyopathy in particular, was commonly present in cats that died unexpectedly in this study population. Subendocardial fibrosis and intramural arteriolosclerosis were more common in cats with unexpected death with cardiac disease than in other cats.

Cardiac biomarkers in cats

Cardiac biomarkers have been used in cats as part of the clinical assessment of heart disease for over a decade. They are widely available to practitioners through commercial reference laboratories. The evidence base for the use of cardiac biomarkers (primarily N-terminal pro-B type natriuretic peptide and cardiac troponin I) in cats is comprehensively reviewed in this article, focusing on each of six specific areas: distinguishing cardiac from non-cardiac causes of respiratory distress; measurement of cardiac biomarkers in urine and pleural fluid; identification of occult cardiomyopathy; effects of systemic disease on circulating concentrations of cardiac biomarkers; point-of-care biomarker testing, and the possible prognostic utility of cardiac biomarker measurement.

Association of tricuspid annular plane systolic excursion with survival time in Boxer dogs with ventricular arrhythmias

Background

Tricuspid annular plane systolic excursion (TAPSE) is a useful estimate of right ventricular function in humans. Reference intervals for dogs have been generated, but the value of measuring TAPSE in other diseases, or investigating the association between TAPSE and outcome, is unknown.

Hypothesis

TAPSE is lower in Boxer dogs with ≥50 VPCs/24 h on Holter than in dogs with fewer ventricular ectopics, and lower TAPSE is associated with a shorter survival time.

Animals

Fifty Boxer dogs that presented for investigation of syncope or suspected arrhythmogenic right ventricular cardiomyopathy (ARVC) at a veterinary teaching hospital (2004–2011).

Methods

Retrospective study. Clinical records, Holter, and echocardiographic data were reviewed. TAPSE was measured in a blinded manner on stored echocardiographic cine‐loops using anatomic M‐mode. Outcome information was obtained and death was classified as cardiac or noncardiac. Survival analysis was performed using Kaplan‐Meier curves and Cox proportional hazards models.

Results

TAPSE was lower in Boxers with ≥50 VPCs/24 h (13.9 ± 4.04 mm) than Boxers with <50 VPCs/24 h (16.8 ± 3.21 mm; P < .001). TAPSE <15.1 mm was associated with shorter cardiac survival time in all dogs (P = .004) and also in dogs without left ventricular dysfunction (P = .035). When controlling for other variables, including ventricular tachycardia on Holter and left ventricular systolic dysfunction, multivariable analysis showed that TAPSE remained an independent predictor of time to cardiac death (HR >4.09, 95%CI 1.15–16.9, P < .029).

Conclusions and Clinical Importance

TAPSE offers prognostic value for Boxer dogs, including those with apparently normal systolic function and ≥50 VPCs/24 h on Holter analysis.

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.

Retrospective evaluation of moderate-to-severe pulmonary hypertension in dogs naturally infected with Angiostrongylus vasorum

OBJECTIVES

The outcome in dogs with pulmonary hypertension associated with natural Angiostrongylus vasorum infection is unclear. This study aimed to report long-term outcome of dogs with A. vasorum and pulmonary hypertension, and to evaluate factors associated with pulmonary hypertension development. It was hypothesised that dogs with pulmonary hypertension had a shorter survival time than dogs without pulmonary hypertension.

METHODS

Retrospective review of clinical records of dogs diagnosed with A. vasorum. Dogs were classified as having or not having pulmonary hypertension based on clinical signs and imaging findings. Signalment, signs and outcome were recorded. DNA obtained from banked samples was genotyped for the PDE5a:E90K polymorphism, a possible factor in development of pulmonary hypertension.

RESULTS

The proportion of dogs with moderate-to-severe pulmonary hypertension and A. vasorum infection in the study population was 14 · 6%. No difference in the population characteristics or PDE5a genotype was detected between dogs with and without pulmonary hypertension. Dogs with pulmonary hypertension had a significantly shorter survival time (P = 0 · 006) and a greater risk of death within 6 months of diagnosis (odds ratio 12 · 5, 95% confidence interval 2 · 1 to 74 · 9; P = 0 · 0053).

CLINICAL SIGNIFICANCE

A. vasorum-associated pulmonary hypertension is an important problem in naturally infected dogs and has a negative effect upon survival.

Plasma cardiac troponin I concentration and cardiac death in cats with hypertrophic cardiomyopathy

BACKGROUND

The use of cardiac biomarkers to assist in the diagnosis of occult and symptomatic hypertrophic cardiomyopathy (HCM) in cats has been established. There is limited data describing their prognostic utility in cats with HCM.

HYPOTHESIS

Circulating concentrations of N-terminal B-type natriuretic peptide (NTproBNP) and cardiac troponin I (cTnI) predict cardiac death in cats with HCM.

ANIMALS

Forty-one cats diagnosed with HCM at a veterinary teaching hospital, between February 2010 and May 2011.

METHODS

Prospective investigational study. Plasma samples were collected from cats diagnosed with HCM and concentrations of NTproBNP and cTnI were analyzed at a commercial laboratory. Echocardiographic measurements from the day of blood sampling were recorded. Long-term outcome data were obtained. Associations with time to cardiac death were analyzed using Cox proportional hazards models.

RESULTS

When controlling for the presence/absence of heart failure and echocardiographic measures of left atrial size and function, cTnI > 0.7 ng/mL was independently associated with time to cardiac death. In univariable analysis, NTproBNP > 250 pmol/L was associated with cardiac death (P = .023), but this did not remain significant (P = .951) when controlling for the effect of clinical signs or left atrial size/function.

CONCLUSIONS AND CLINICAL IMPORTANCE

Plasma concentration of cTnI (cutoff >0.7 ng/mL) is a predictor of cardiac death in cats with HCM that is independent of the presence of heart failure or left atrial dilatation.

Comparison of computed tomography pulmonary angiography and point-of-care tests for pulmonary thromboembolism diagnosis in dogs

OBJECTIVES

To evaluate the feasibility of CT pulmonary angiography for identification of naturally occurring pulmonary thromboembolism in dogs using predefined diagnostic criteria and to assess the ability of echocardiography, cardiac troponins, D-dimers and kaolin-activated thromboelastography to predict the presence of pulmonary thromboembolism in dogs.

METHODS

Twelve dogs with immune-mediated haemolytic anaemia and evidence of respiratory distress were prospectively evaluated. Dogs were sedated immediately before CT pulmonary angiography using intravenous butorphanol. Spiral CT pulmonary angiography was performed with a 16 detector-row CT scanner using a pressure injector to infuse contrast media through peripheral intravenous catheters. Pulmonary thromboembolism was diagnosed using predefined criteria. Contemporaneous tests included echocardiography, arterial blood gas analysis, kaolin-activated thromboelastography, D-dimers and cardiac troponins.

RESULTS

Based on predefined criteria, four dogs were classified as pulmonary thromboembolism positive, three dogs were suspected to have pulmonary thromboembolism and the remaining five dogs had negative scans. The four dogs identified with pulmonary thromboembolism all had discrete filling defects in main or lobar pulmonary arteries. None of the contemporaneous tests was discriminant for pulmonary thromboembolism diagnosis, although the small sample size was limiting.

CLINICAL SIGNIFICANCE

CT pulmonary angiography can be successfully performed in dogs under sedation, even in at-risk patients with respiratory distress and can both confirm and rule out pulmonary thromboembolism in dogs.

Arterial thromboembolism in 250 cats in general practice: 2004-2012

Background

Population characteristics and outcome of cats with arterial thromboembolism (ATE) managed in general practice (GP) have been poorly described.

Hypothesis

Cats with ATE presenting to GP are usually euthanized at presentation, but survival times >1 year are possible.

Animals

Cats with ATE managed by 3 GP clinics in the United Kingdom.

Methods

Records of cases presenting to GP over a 98‐month period (2004–2012) were reviewed. Cats with an antemortem diagnosis of limb ATE were included. Outcome information was obtained.

Results

Over 98 months, 250 cats were identified with ATE. Prevalence was approximately 0.3%. At presentation, 153 cats (61.2%) were euthanized, with 68/97 (70.1%) of the remaining cats (27.2% of the total population) surviving >24 hours after presentation. Of these, 30/68 (44.1%) survived for at least 7 days. Hypothermia (HR, 1.44; 95% CI, 1.002–2.07; P = .049) and management by Clinic 2 (HR, 5.53; 95% CI, 1.23–24.8; P = .026) were independent predictors of 24‐hour euthanasia or death. For cats surviving >24 hours, hypothermia (HR, 2.25; 95% CI, 1.12–4.48; P = .021) and failure to receive aspirin, clopidogrel, or both (HR, 8.26; 95% CI, 1.39–50; P = .001) were independent predictors of euthanasia or death within 7 days. For cats that survived ≥7 days, median survival time was 94 (95% CI, 42–164) days, with 6 cats alive 1 year after presentation.

Conclusions

Although 153/250 cats were euthanized at presentation, 6 cats survived >12 months. No factors were identified that predicted euthanasia on presentation.

Prognostic value of 24-hour ambulatory ECG (Holter) monitoring in Boxer dogs

BACKGROUND

Boxer dogs are reported to be predisposed to arrhythmogenic right ventricular cardiomyopathy (ARVC), but the natural history has not been well characterized and inconsistent diagnostic criteria have been applied to identify affected dogs. Echocardiographic examination findings are unremarkable in many affected Boxer dogs, and in these dogs, 24-hour ambulatory ECG (Holter) monitoring often is used for diagnostic and prognostic purposes, despite limited information available relating Holter findings to outcome.

HYPOTHESIS/OBJECTIVES

Boxers with complex ventricular arrhythmias at initial presentation will have shorter survival times. The objective was to investigate the prognostic value of Holter monitoring in Boxer dogs.

ANIMALS

One hundred and twenty-two Boxer dogs seen at 3 university referral hospitals.

METHODS

Retrospective study. Survival times were obtained for Boxer dogs evaluated by echocardiography and a 24-hour Holter ECG. Kaplan-Meier survival analysis was used to estimate the median survival time and Cox proportional hazards analysis was used to identify variables independently associated with cardiac mortality.

RESULTS

Outcome data were obtained for 122/163 dogs meeting the inclusion criteria. Of the 70 dogs that had died, 45 were considered to have suffered cardiac-related deaths. Median survival was significantly longer in dogs with a left ventricular systolic diameter (LVIDs) ≤ 35 mm compared with those with LVIDs > 35 mm (P < .001). Multivariable analysis in dogs with LVIDs ≤ 35 mm showed that the presence of ventricular tachycardia, age >4.5 years, and male sex were independent predictors of cardiac mortality.

CONCLUSIONS AND CLINICAL IMPORTANCE

Holter monitoring in Boxer dogs provides valuable prognostic information.

Circulating natriuretic peptide concentrations in hyperthyroid cats

OBJECTIVES

To assess the influence of thyroid function on natriuretic peptide concentration in hyperthyroid cats before and after treatment.

METHODS

Serum natriuretic peptide concentration was measured in 61 hyperthyroid cats recruited from first-opinion clinics before and after treatment.

RESULTS

Following successful treatment, total thyroxine, heart rate, systolic blood pressure and packed cell volume all decreased and bodyweight and creatinine concentrations increased. Furthermore, a significant (P < 0·001) decline in NT-proBNP concentration but not NT-proANP was identified.

CLINICAL SIGNIFICANCE

Thyroid function has a modest but significant effect on NT-proBNP concentration. Thyroid status should be taken into account when interpreting NT-proBNP concentrations in cats.

Population characteristics and survival in 127 referred cats with hypertrophic cardiomyopathy (1997 to 2005)

OBJECTIVES

To evaluate the characteristics and survival of a recent population of cats with hypertrophic cardiomyopathy.

METHODS

Records at the Royal Veterinary College Queen Mother Hospital for Animals were searched for cats diagnosed with hypertrophic cardiomyopathy between 1997 and 2005. Referring veterinarians and owners were contacted to determine survival times.

RESULTS

Cats with hypertrophic cardiomyopathy were evaluated for population characteristics (n=127) and survival times (n=109). Overall median survival from date of hypertrophic cardiomyopathy diagnosis at the Queen Mother Hospital for Animals was 1276 days. Cats with hypertrophic cardiomyopathy were younger (P=0·009), and more likely to be male (P<0·001) compared to a hospital control group (n=1473), and Ragdolls were over-represented (P<0·05). Characteristics associated with increased survival in univariate analysis included younger age (P=0·007), asymptomatic status (P<0·001), normal left atrial size (P<0·001) and presence of systolic anterior motion of the mitral valve (P=0·003). Systolic anterior motion was associated with asymptomatic status, and did not influence survival in asymptomatic cats or those in congestive heart failure. Age, left atrial size and breed were significantly associated with survival time in a multivariate analysis.

CLINICAL SIGNIFICANCE

Cats with hypertrophic cardiomyopathy and left atrial enlargement have a poorer prognosis. The positive influence of systolic anterior motion on survival is likely to be linked to its association with asymptomatic status.

N-terminal pro B-type natriuretic peptide and left ventricular diameter independently predict mortality in dogs with mitral valve disease

OBJECTIVES

To determine whether natriuretic peptide concentrations would predict all cause mortality in dogs with degenerative mitral valve disease.

METHODS

One hundred dogs with naturally occurring degenerative mitral valve disease were prospectively recruited for this longitudinal study. Analysis of outcome was undertaken for 73 dogs for which the outcome was known. Dogs underwent physical examination, electrocardiography and echocardiography. Natriuretic peptide concentrations were measured by Enzyme-linked immunosorbent assay. The ability of natriuretic peptide concentrations, clinical, electrocardiographic and echocardiographic data, to predict all cause mortality was determined using univariable and multivariable Cox proportional hazards analyses.

RESULTS

Thirty dogs died during the period of follow-up. Two variables were independently predictive of all cause mortality; these were the normalised left ventricular end-diastolic diameter and the N-terminal pro B-type natriuretic peptide concentration. An increase of the left ventricular end-diastolic diameter by 0.1 increased the hazard of all cause mortality by 20% (95% confidence interval: 4 to 37%, P=0.01) and a 100 pmol/l increase in N-terminal pro B-type natriuretic peptide increased the hazard by 7% (95 confidence interval: 2 to 11%, P=0.003).

CLINICAL SIGNIFICANCE

N-terminal pro B-type natriuretic peptide concentration and left ventricular end-diastolic diameter are significantly and independently predictive of all cause mortality in dogs with degenerative mitral valve disease.

Circulating natriuretic peptides in cats with heart disease

BACKGROUND

Circulating natriuretic peptide concentrations are increased in cats with myocardial dysfunction.

HYPOTHESIS

Serum N-terminal fragment of proatrial natriuretic peptide (NT-proANP) and NT-probrain natriuretic peptide (proBNP) concentrations may predict the presence of heart disease (HD) and congestive heart failure (CHF). A positive relationship is also predicted among natriuretic peptide (NP) concentrations, a noninvasive estimate of left ventricular filling pressure (E/E(a)), and an echocardiographic measure of left atrial (LA) size (LA/aortic diameter [Ao]).

METHODS

Serum NP concentrations were measured in 28 healthy control and 50 study cats using sandwich enzyme immunoassays. The study group comprised cats, with HD but no CHF (HD - CHF, n = 17) and cats with CHF (HD + CHF, n = 33). The relationship among NP concentrations, LA size, and E/E(a) was examined. The ability of NP to distinguish control from study cats, and HD - CHF from HD + CHF cats, was explored using receiver operator curve analysis.

RESULTS

NP concentrations were significantly lower in control than in study cats (P= .0001). The NT-proBNP concentrations were positively correlated with LA/Ao ratio (rho= 0.34; P= .02) and with E/E(a) ratio (rho= 0.68; P < .05). An NT-proBNP concentration of 49 fmol/mL gave a sensitivity and specificity of 100 and 89.3%, respectively, for correctly distinguishing 96.2% of control from study cats. Pairwise comparisons of the areas under the curve identified a statistically significant difference (P= .011) between NT-proANP and NT-proBNP to distinguish control from study cats. NT-proANP and NT-proBNP concentrations were significantly higher in HD + CHF cats than in HD - CHF cats (P= .0023 and .0001, respectively).

CONCLUSIONS

Serum concentrations of NT-proANP and particularly NT-proBNP were different in healthy control cats, asymptomatic cats with HD, and cats with CHF, suggesting that measurement of NP concentrations may prove clinically useful as an initial screening test for cats with suspected cardiac disease.

Pulsus alternans in English cocker spaniels with dilated cardiomyopathy

OBJECTIVES

To report the clinical findings associated with pulsus alternans in English cocker spaniels with dilated cardiomyopathy and to review the phenomenon of mechanical alternans, usually found in patients with severe left ventricular systolic dysfunction.

METHODS

The case records of 10 English cocker spaniels with dilated cardiomyopathy and pulsus alternans were reviewed. All dogs had been referred in moderate to severe congestive heart failure. Pulsus alternans was clinically recognised by palpation of a regular alternation of femoral pulse amplitude and confirmed by echocardiography in all cases. Pulsus alternans was an intermittent finding in all 10 dogs.

RESULTS

Phonocardiographic recordings were obtained in three dogs to document variation in the intensity of the heart sounds, with one case exhibiting absence of the second heart sound in alternate beats. M-mode echocardiography performed in all dogs showed alternation of the pattern of mitral valve diastolic motion. Doppler echocardiography showed marked alternation in stroke volume in the aortic outflow in all cases. It also showed alternation in mitral regurgitation and in the velocity of early ventricular filling.

CLINICAL SIGNIFICANCE

Pulsus alternans may be more prevalent in English cocker spaniels than in other breeds, and because of its intermittent nature, its incidence may be higher than that previously reported. It has diagnostic relevance as it usually indicates severe myocardial depression. Echocardiography allows non-invasive detection of mechanical alternans and provides further insights into its pathophysiology and clinical significance.

Double chambered right ventricle in 9 cats

BACKGROUND

Double-chambered right ventricle (DCRV) is a frequently recognized cardiac congenital abnormality in humans. It has been described in dogs and in 1 cat. However systemic description of clinical and echocardiographic features of the disease in cats is currently lacking from the veterinary literature.

ANIMALS

Nine cats with DCRV are described.

RESULTS

The cats ranged from 4 months to 10 years of age. Eight cats at presentation were asymptomatic and 1 cat had chylothorax. In all cases echocardiography revealed abnormal fibromuscular bundles obstructing the mid-right ventricle, dividing the chamber into 2 compartments. The proximal right ventricular compartment was markedly hypertrophied, and right atrial dilation was usually present. The mean pressure gradient measured across the stenotic area was 130 +/- 50 mm Hg. Concurrent abnormalities included a ventricular septal defect (n = 2); aortic malalignment, aortic insufficiency (n = 1); and congenital peritoneal-pericardial diaphragmatic hernia (n = 1). Two cats had systolic anterior motion of the mitral valve, one of which had concurrent left ventricular hypertrophy. Five cats have remained asymptomatic for a median period of 3.6 years (range, 3.3-5 years) and 3 cats have developed clinical signs associated with congestive heart failure (at 2, 3.3, and 9 years). One cat showed progressive lethargy and exercise intolerance and underwent partial ventriculectomy at the age of 2 years. This cat died during the operation with electromechanical dissociation.

CONCLUSIONS

DCRV is a congenital cardiac abnormality that may be more common than previously recognized.

Effects of age, body weight, and heart rate on transmitral and pulmonary venous flow in clinically normal dogs

OBJECTIVE

To determine the influence of age, body weight (BW), heart rate (HR), sex, and left ventricular shortening fraction (LVSF) on transmitral and pulmonary venous flow in clinically normal dogs.

ANIMALS

92 client-owned dogs 3 months to 19 years old.

PROCEDURE

Transthoracic Doppler echocardiography recordings of transmitral flow and pulmonary venous flow were obtained in conscious unsedated dogs. Influence of age, BW, HR, sex, and LVSF on diastolic variables was assessed, using statistical methods such as ANOVA on ranks and univariate and multivariate forward stepwise linear regression analyses.

RESULTS

Age significantly influenced isovolumic relaxation time (IVRT, r = 0.56), ratio between peak velocity of the early diastolic mitral flow wave-to-peak velocity of late diastolic mitral flow wave (E:A; r = -0.44), deceleration time of early diastolic mitral flow (DTE; r = 0.26), and peak velocity of atrial reversal pulmonary venous flow wave (AR-wave; r = 0.37). Significant changes of mitral inflow and pulmonary venous flow variables were evident only in dogs > 6 and > 10 years old, respectively. Body weight significantly influenced DTE (r = 0.63), late diastolic flow duration (r = 0.60), and AR duration (r = 0.47), whereas HR significantly affected DTE (r = -0.34), IVRT (r = -0.33), and peak velocity of AR (r = 0.24). Sex or LVSF (range 22 to 48%) did not influence any echocardiographic variables.

CONCLUSIONS AND CLINICAL RELEVANCE

Age, BW, and HR are important factors that affect filling of the left atrium and left ventricle in clinically normal dogs.

Sick sinus syndrome in nine West Highland white terriers

Sick sinus syndrome is a clinical term used to describe the clinical signs of sinus node dysfunction. This paper describes the clinical data from nine West Highland white terriers, eight females and one male, in which a diagnosis of sick sinus syndrome was made. The most common clinical signs were episodic weakness and presyncope. Electrocardiographic findings included sinus bradycardia, sinus arrest with or without escape complexes, disturbances of atrioventricular conduction, paroxysmal supraventricular tachycardia, or some combination of these dysrhythmias. The main radiographic changes were mild right-sided cardiomegaly in five cases, and a slight increase in bronchial and interstitial markings in four, but there was no evidence of congestive heart failure in any of the dogs. Echocardiography revealed mild to moderate mitral endocardiosis in three cases with no other significant abnormalities. The dogs' responses to parenteral atropine were variable and were not necessarily related to their response to oral anticholinergic agents. Five of the dogs were initially treated with propantheline bromide, but in only two of them were the clinical signs controlled in the long term. Six of the dogs were successfully treated by the implantation of a transvenous pacemaker.

Mitral annulus motion as determined by M-mode echocardiography in normal dogs and dogs with cardiac disease

M-mode echocardiography was used to assess apical mitral annulus motion (MAM) in 103 normal dogs and 101 dogs with cardiac disease, to obtain information on systolic left ventricular long axis function. In normal dogs, a close relationship was found between MAM and body weight (r = 0.80, P < 0.001). There was a weak correlation between MAM and heart rate (r = -0.25, P < 0.05), but no correlation between MAM and age or left ventricular shortening fraction (P > 0.05). Mean MAM (95% confidence intervals) were established for normal dogs of differing body weight, and were 0.70 cm (0.65 to 0.75) in dogs < 15 kg, 1.08 cm (1.03 to 1.13) in dogs weighing 15 to 40 kg, and 1.51 cm (1.21 to 1.81) in dogs > 40 kg. "Cut-off" values to define decreased MAM for normal dogs of differing body weight were 0.45 cm (dogs < 15 kg), 0.80 cm (dogs 15-40 kg), and 1.20 cm (dogs > 40 kg). In dogs with cardiac disease, median MAM was normal in mitral valve endocardiosis or aortic stenosis, but significantly decreased (P < 0.05) in dilated cardiomyopathy. All dogs with mitral valve endocardiosis (n = 54) or aortic stenosis (n = 26) had MAM above the above-mentioned "cut-off" values, suggesting normal or increased left ventricular longitudinal systolic shortening, whereas 81% (17/21) of dogs with dilated cardiomyopathy had MAM below the "cut-off" value, indicating decreased long axis systolic function. It is concluded that MAM may be used to evaluate systolic left ventricular long axis performance in dogs and may add useful information on global left ventricular contraction dynamics.

Progression of aortic stenosis in the boxer

Thirty-five boxers that had been referred to the Royal (Dick) School of Veterinary Studies between 1989 and 1994 with left heart base murmurs and aortic velocities greater than 1.5 m/second on Doppler echocardiography were recalled for clinical examination and Doppler echocardiography between 1995 and 1996. Five dogs (14 per cent) showed an increase in murmur grade on repeat visit. Six dogs (17 per cent) showed an increase in aortic velocity of greater than 20 per cent. Eight dogs (23 per cent) had developed aortic valvular or subvalvular two-dimensional echocardiographic changes that had not been present at the initial visit. Seven dogs (20 per cent) had developed aortic regurgitation, and three dogs (8 per cent) mitral regurgitation.

Chronic pulmonary disease in West Highland white terriers

This paper describes the clinical features, and diagnostic findings of a chronic respiratory condition in 29 West Highland white terriers. Typically, the dogs were coughing chronically, had dyspnoea and tachypnoea of varying severity, and had deteriorated progressively over months to years. The mean (sem) survival time in months from the clinical signs being first noted by the owners was 17.9 (2.3). Most cases had a combination of respiratory signs, but coughing was the predominant sign in 18 cases. Inspiratory crackles were audible on chest auscultation in 28 cases, 10 of which were also wheezing. Rhonchi were the predominant sound in the remaining case. The main radiographic changes were mild to severe increased Interstitial markings in all cases, with additional bronchial markings in 14 of the dogs. Right-sided cardiomegaly (cor pulmonale) was recorded in 15. Bronchoscopic findings in 17 of the dogs were either normal or involved a mild airway mucoid reaction in eight. Chronic mucosal changes were observed in eight, but in two this finding was equivocal. Dynamic changes to the lumen of the airway were present in seven cases. No significant haematological or biochemical changes could be detected in 20 cases, but four cases were hypercholestrolaemic. A histopathological assessment of four cases revealed alveolar septal fibrosis to be the predominant change. Prednisolone, with or without bronchodilators, was the most commonly used therapy, and the response was variable. The condition appears to be associated with significant pulmonary interstitial fibrosis of unknown aetiology and has clinical similarities to idiopathic pulmonary fibrosis (cryptogenic fibrosing alveolitis) in human beings.

Analysis of murmur intensity, duration and frequency components in dogs with aortic stenosis

A study was undertaken to investigate the relationship between murmur intensity, murmur duration, duration to peak intensity and frequency components with degree of aortic stenosis in boxers. Measurements were made from phonocardiograms obtained from 35 boxers with ejection-type murmurs, and values were compared with those obtained for aortic flow velocity measured by Doppler echocardiography. Murmur intensity graded by auscultation was significantly correlated with aortic flow velocity (P < 0.001), and murmur duration, expressed as a percentage of systole was significantly correlated with aortic flow velocity (P < 0.001), independent of heart rate. Dogs with early systolic murmurs not exceeding 50 per cent of systole had aortic flow velocities of less than 1.5 m/second and no echocardiographic abnormalities, in contrast with dogs with murmurs of longer duration. Dogs with only high frequency components had lower aortic velocities than those that also had components in the medium frequency range (P < 0.01).

[Doppler echocardiographic assessment of left ventricular diastolic function in dogs]

Pulmonary venous flow velocity pattern, transmitral flow pattern, isovolumic relaxation time, and left ventricular fractional wall thinning were analyzed in 72 dogs with heart disease by transthoracic Doppler and M-mode echocardiography and compared with other noninvasive variables of left ventricular and left atrial systolic performance. Abnormal diastolic blood flow was found in 49 (68%) dogs, predominantly flow patterns suggestive of relaxation abnormality and increased filling pressures. Diastolic flow abnormalities despite normal systolic performance were found in 23 (32%) dogs of which 14 (61%) revealed clinical signs of heart disease. The diagnostic sensitivity of pulmonary venous flow parameters for echocardiographically detectable diastolic disturbance was found to be higher compared with the other noninvasive parameters of diastolic heart function measured. Diastolic filling pattern appear to correlate closer with functional status in many dogs with heart disease than indices of systolic performance.

Pulmonary venous flow characteristics as assessed by transthoracic pulsed Doppler echocardiography in normal dogs

Transthoracic Doppler echocardiography was used to evaluate the technique of measuring and normal patterns of pulmonary venous flow in fourteen normal dogs. Polyphasic pulmonary venous flow profiles were obtained in all dogs, consisting of one (S) or two (SE and SL) systolic forward flow waves, one early diastolic forward flow wave (D), one reverse flow wave (R) related to atrial contraction, and one reverse flow wave (R2) observed after cessation of systolic flow. Pulmonary venous flow was laminar in 9 dogs (65%). Maximal flow velocity during systole (0.39 +/- 0.14 m/sec) was significantly lower (P < 0.01) than in early diastole (0.56 +/- 0.14 m/sec). During late diastole peak flow velocity was 0.20 +/- 0.08 m/sec and maximum R2 velocity was 0.17 +/- 0.05 m/sec. Duration of mitral A-wave was significantly greater (P < 0.05) than R-wave duration in all dogs (0.075 +/- 0.010 vs 0.058 +/- 0.012 sec). These results can be used for comparison with patterns found in disease states.

Persistent left cranial vena cava associated with multiple congenital anomalies in a six-week-old puppy

A six-week-old male puppy was presented with a distended abdomen, dypsnoea and cyanosis. Auscultation revealed a grade II/VI systolic murmur. Thoracic radiographs showed gross cardiomegaly. An electrocardiogram revealed a narrow-complex tachycardia, deep S waves in leads I, II, III and aVF, and negative P waves in lead III. Two-dimensional echocardiography showed a high ventricular septal defect and marked dilation of the right-sided chambers. There was also an echolucent structure lateral to the left atrium at a site corresponding to the coronary sinus. Contrast echocardiography revealed right-to-left shunting through the septal defect. Necropsy confirmed the existence of a septal defect in the membranous part of the septum and a persistent left cranial vena cava with dilation of the coronary sinus. In addition, a small patent ductus arteriosus and tricuspid dysplasia were present.

Measurement of cyclic variation in ultrasonic integrated backscatter in conscious, unsedated, clinically normal dogs

OBJECTIVE

To assess the feasibility and repeatability of measuring ultrasonic integrated backscatter in unsedated conscious dogs, using a protocol previously validated in pigs with open thorax.

ANIMALS

11 clinically normal conscious unsedated German Shorthair Pointers.

PROCEDURE

A modified commercially available echocardiography system was used to record long-axis views of the heart. The radiofrequency data from 15 consecutive frames were digitized and analyzed. Regions of interest were chosen within the myocardium, and the ultrasonic integrated backscatter within each region was calculated in the time domain for each frame.

RESULTS

Cyclic variation in integrated backscatter values was observed, with maximal values at end-diastole and minimal values at end-systole. Mean +/-SD amplitude of cyclic variation was 5.81 +/- 3.86 dB over all the regions chosen.

CONCLUSIONS

Results agreed with those obtained by other investigators working with dogs with open thorax and those with closed thorax while under general anesthesia. The analysis of the components of variance indicates that this is a consistent, reliable technique in conscious unsedated dogs.

CLINICAL RELEVANCE

Integrated ultrasonic backscatter measurement provides a noninvasive means of tissue characterization. Use of this protocol reliably yields cyclic variation in integrated backscatter and could be applied clinically to dogs with myocardial disease.

Feline asthma syndrome: a retrospective study of the clinical presentation in 29 cats

Feline asthma syndrome (FAS) is a clinical condition characterised by recurrent bouts of coughing, wheezing and, or, dyspnoea. While the aetiology is unproven, the condition is believed to involve a type I immediate hypersensitivity reaction to inhaled allergens. In this paper the clinical data from 29 cats, where a diagnosis of FAS was made, are assessed retrospectively. The most common clinical presentation was recurrent bouts of coughing (n = 26) and dyspnoea (n = 21). Radiographic changes were noted in 24 cats, which included increased bronchial (n = 5), interstitial (n = 7) and mixed (n = 12) (bronchial and interstitial) patterns. Right middle lung lobe collapse was noted in two cats. Abnormal bronchial cytology was present in 16 cats. A predominant eosinophilic sample was collected in only three cats. There were minimal changes in differential white cell counts, and mild eosinophilia was found in only five cats. Prednisolone alone was the most effective therapy, although avoidance of putative aeroallergens and antibacterial therapy was effective in some. On the basis of the data from these cases it would appear that the diagnosis of FAS depends largely on the clinical presentation and radiographic findings. The value of ancillary tests in the diagnosis of FAS appears to be limited.