Evaluation of shock waveform configuration on the defibrillation capacity of implantable cardioverter defibrillators in dogs

BackgroundImplantable cardioverter defibrillators (ICD) are programmed to detect ventricular arrhythmias and terminate them by delivering an electrical shock. A defibrillation threshold (DFT) at least 10 J below the maximum device output is recommended for successful therapy. Shock waveform configuration is a programmable parameter used to achieve a low DFT. It is hypothesized that a fixed-pulse configuration results in lower defibrillation energy requirements than a fixed-tilt configuration.Animals10 mongrel dogs.Materials and methodsICD generator and transvenous lead were surgically implanted. Defibrillation threshold was determined using a protocol guided by the upper limit of vulnerability. Fixed-pulse and fixed-tilt (50%/50%) waveform configurations were tested in a random order. Plasma cardiac troponin I (cTnI) was measured for signs of myocardial injury.ResultsThe experiment was completed in 9 dogs. Overall mean DFT value was 424 ± 88 V (9.2 ± 3.9 J). Mean differences among voltage, energy and impedance at the DFT for fixed-pulse (422 ± 97 V, 9.1 ± 4.2 J, 62.6 ± 13.8 Ω) and fixed-tilt (426 ± 83 V, 9.3 ± 3.8 J, 62.8 ± 18.5 Ω) configurations were not statistically significant (All P > 0.21). Cardiac TnI concentration changed from 0.03 ng/mL (95% CI: 0.02–0.04) at baseline to 0.11 ng/mL (95 CI: 0.08–0.16) after DFT was obtained with the first waveform configuration and 0.19 ng/mL (95% CI: 0.13–0.28) at the end of the study period. There were no significant changes in heart rate, end-tidal CO2 and blood pressure over time (all P > 0.09).ConclusionThe tested ICD device and lead placement reliably produced acceptable DFT values, based on a 10-J safety margin below the maximum device output. A benefit of fixed-pulse configuration could not be demonstrated over the standard fixed-tilt waveform. Signs of acute myocardial damage from repeated high-voltage shocks and episodes of ventricular fibrillation seemed of limited clinical significance.     

Sudden cardiac death in a dog during Holter recording—R on T phenomenon

A 6-year-old castrated male Golden Retriever was diagnosed with severe subaortic stenosis with severe left atrial enlargement and high heart rate due to atrial fibrillation. Treatment with digoxin and diltiazem to control ventricular response rate was initiated. Ambulatory electrocardiographic monitoring (Holter monitoring) was performed at the beginning of treatment and was repeated to evaluate the patient's response to drug therapy. Drug dose adjustments were made based on response to therapy as assessed by Holter monitoring. The dog experienced sudden death at home 19 days after beginning treatment while wearing the Holter monitor. Analysis of the Holter recording revealed marked increase in number and complexity of ventricular arrhythmias. A ventricular premature complex occurring on a T wave (R on T) was noted preceding the polymorphic ventricular tachycardia. This arrhythmia immediately degenerated into ventricular fibrillation followed by asystole. This case report describes the arrhythmia that preceded cardiac arrest and reviews the risk factors that could have potentiated the fatal arrhythmia in this dog.     

肉鸡腹水症发病机理研究Ⅳ.肉鸡和蛋仔鸡左右心室功能的比较研究

试验选用快速生长的艾维茵肉鸡和海兰蛋仔鸡 ,各试验组用右心导管法和左心导管法测定肺动脉压(PAP)、右心室收缩压 (RVSP)、左心室收缩压 (LVSP)、左右心室内压最大变化速率 (+dp/dt)的动态变化。并且比较了相同体重健康蛋仔鸡、肉鸡的左右心室功能变化特点。结果表明 :相同日龄肉鸡肺动脉压显著高于蛋仔鸡 ;2 8、35日龄肉鸡右心收缩压显著高于蛋仔鸡 (P <0 0 5) ,2 8、35、42和 49日龄肉鸡左心室收缩压低于蛋仔鸡 ,且差异极显著 (P <0 0 1 )。肉鸡左心室内压最大变化速率 (LV +dp/dt)从 2 1日龄测定起呈现显著性低于同日龄的蛋仔鸡。相同体重的肉鸡和蛋鸡相比 ,肉鸡肺动脉压 (PAP)显著高于蛋仔鸡 ,但肉鸡右心室内压最大变化速率 (RV +dp/dt)、左心室收缩压 (LVSP)、左心室内压最大变化速率 (LV +dp/dt)显著低于蛋仔鸡。这提示肉鸡先天存在着肺动脉压较高、左心室病理性功能低下 ,这可能是肉鸡容易发生腹水症的原因之一     

Ventricular Arrhythmias in Dogs With Splenic Masses

The records of 73 dogs with splenic masses were evaluated retrospectively to determine whether ventricular arrhythmias, in the absence of clinically apparent underlying heart disease, were a common clinical finding. Associated clinical, laboratory, and pathologic findings were evaluated to search for clinical predictors of ventricular arrhythmias. Age, breed, weight, sex, coagulation abnormalities, electrolyte abnormalities, and hemoabdomen were unrelated to the development of arrhythmias (p > 0.05). Anemia was associated with the presence of arrhythmias (p = 0.005). Myocardial necrosis (10/18) and metastatic hemangiosarcoma (3/18) were common myocardial histopathologic findings. Proposed causes for arrhythmias in dogs with splenic masses include myocardial metastases, tissue hypoxia secondary to anemia or hypovolemia, and local or systemic catecholamine release.     

Evaluation of NT-pro BNP and CT-ANP as markers of concentric hypertrophy in dogs with a model of compensated aortic stenosis

Background: Serum C-terminal atrial natriuretic peptide (CT-ANP) and N-terminal pro B-type natriuretic peptide (NT-pro BNP) concentrations have not been measured serially in dogs with chronic pressure overload of the heart.
Hypothesis: We investigated whether serial evaluation of CT-ANP and NT-pro BNP concentrations is a useful guide to the risk of cardiac remodeling in dogs with a model of aortic stenosis.
Animals: Six male Beagles.
Methods: After anesthesia, the aorta was constricted with a polyester band and mean left ventricular systolic pressure (LVPs) was 50 mmHg above baseline. Echocardiographic and intracardiac catheter examinations and blood sampling were performed before surgery and 3 and 6 months after surgery.
Results: LVP and left ventricular end-diastolic pressure (LVEDP) were significantly higher at 6 months. Compared with baseline, end-diastolic intraventricular septum thickness (IVSd), left ventricular posterior wall thickness (LVPWd), and relative wall thickness (RWT) were significantly increased 3 and 6 months after aortic constriction. Serum CT-ANP concentrations were increased significantly at 3 months and serum NT-pro BNP concentrations were significantly higher 3 and 6 months after aortic constriction. Serum NT-pro BNP concentration was significantly correlated with LVEDP and IVSd whereas serum CT-ANP concentration was not correlated with any measurement. Stepwise regression analysis showed that LVEDP, IVSd, and RWT could predict serum NT-pro BNP.
Conclusions and Clinical Importance: This study indicated the differential regulation of NT-pro BNP and CT-ANP concentrations during pressure overload. NT-pro BNP assay may be used as an additional screening method to stratify early-stage ventricular remodeling because of aortic constriction.     

肉鸡和蛋鸡心肌易颤性的比较研究

以常规饲养的肉鸡和蛋鸡作为试验动物,通过电刺激诱颤阈和输钾诱颤阈的测定以及进行冷加压试验,对同体重肉鸡和蛋鸡的心肌易颤性进行了比较研究。结果表明:(1)同体重肉鸡和蛋鸡相比,电刺激诱颤阈和输钾诱颤阈肉鸡均极显著低于蛋鸡(P<0.01);(2)在电刺激诱发室颤的过程中,开胸时室颤的发生率肉鸡(14%)显著高于蛋鸡(0%)(P<0.05);(3)冷加压试验:冷加压5min内,心率和PT波宽出现了显著的变化,而且变化幅度肉鸡均明显大于蛋鸡。上述试验结果从不同方面均表明肉鸡心肌易颤性高于蛋鸡。     

Twenty-Four-Hour Ambulatory Electrocardiography in Normal Cats

Twenty-four-hour ambulatory electrocardiograms were recorded in two age groups of 10 normal cats each: group 1 (1 to 4 years) and group 2 (8 to 14 years), with equal numbers of males and females in each group. Average heart rates over the 24-hour recording period ranged from 114 to 202 beats/minute (bpm). The mean 24-hour average rate did not differ between group 1 and group 2 (157.6 vs. 156.3+/-5.3 bpm, respectively); however, females (both groups combined) had higher average heart rates than males (166.8 vs. 147.1+/-5.3 bpm, respectively). Females also had a higher mean minimum heart rate than males (116.9 vs. 96.5+/-4.2 bpm, respectively); but there were no gender or age group differences in maximum heart rate. Results of hourly analyses of average, minimum, and maximum heart rates were similar. Mean heart rates rose from mid-afternoon to about 9:00 PM and were lowest just after midnight. Although regular sinus rhythm predominated, periods of sinus arrhythmia were evident in most cats, especially in early morning hours. Supraventricular extrasystoles were uncommon. Isolated ventricular extrasystoles occurred more frequently in group 2 cats; multiform configuration was observed in both groups. Repetitive ventricular extrasystoles, which usually consisted of occasional couplets, occurred more frequently in group 2 cats. One older cat had 2 short runs of ventricular tachycardia. Another older cat appeared to have a recurrent accelerated idioventricular rhythm.     

Effect of amlodipine on echocardiographic variables in cats with systemic hypertension

Left ventricular hypertrophy signals a poor prognosis in hypertensive humans. Cardiac disease is common in cats with systemic hypertension. The aims of this study were to characterize the echocardiographic findings of cats with systemic hypertension and to determine if reducing the degree of hypertension is associated with resolution of cardiac hypertrophy. Echocardiographic examinations were performed on 19 cats with naturally occurring systemic hypertension. Fourteen of these cats were subsequently studied after a minimum of 3 months of treatment with the antihypertensive agent amlodipine. Hypertensive cats had a significantly thicker interventricular septum in both systole and diastole, thicker left ventricular free wall in both systole and diastole, and larger left atrium compared to the published normal values and 74% (14/19) of the cats met criteria for left ventricular hypertrophy (diastolic septal or free-wall thickness > 0.60 cm). Systolic blood pressure was lower after treatment (217 +/- 25 mm Hg, range: 180-275 mm Hg; and 142 +/- 27 mm Hg, range: 90-200 mm Hg). No difference was found in any of the echocardiographic measurements between the untreated and treated cats, although more cats had ventricular hypertrophy before treatment (11/14) than after initiating amlodipine (6/14; P = .006). Ventricular hypertrophy is common in hypertensive cats and may resolve after the initiation of amlodipine.     

Acute cardiovascular effects of diltiazem in anesthetized dogs with induced atrial fibrillation

Atrial fibrillation (AF) is one of the most important arrhythmias of dogs. In a previous study, we determined the dosage of intravenously administered diltiazem necessary to reduce ventricular response (VR), cardiac output (CO), and mean systemic arterial pressure (P(Ao)) to values similar to those observed during sinus rhythm (SR) before induction of AF. The present study was conducted to establish an acute, effective dosage of diltiazem given PO. AF was produced by rapid atrial pacing in healthy, anesthetized Beagle Hounds. Dogs were instrumented to record hemodynamic and electrophysiological parameters. Four dogs were given 2.5 mg/kg diltiazem, and another 4 dogs were given 5 mg/kg diltiazem by stomach tube, whereas 4 other dogs received vehicle in equivalent volumes. Plasma concentrations of diltiazem were measured at various intervals after dosing. A dosage of 5 mg/kg diltiazem produced plasma concentrations of 32-100 ng/mL 3 hours after administration, concentrations within the published effective range for dogs with naturally occurring AF. Between 2 and 3 hours after this dosage, the rate pressure product (RPP) and an index of left ventricular efficiency returned to values similar to those observed during SR. Thus, we believe that diltiazem at anorally administered dosages of 5 mg/kg should be considered to produce therapeutic blood concentrations and favorable hemodynamic effects in dogs with naturally occurring AF. These data must be extrapolated with caution to dogs with long-standing AF produced by natural causes.     

Phenytoin sodium as a treatment for ventricular dysrhythmia in horses

Five adult horses with ventricular extra systoles (VES) and 2 with ventricular tachycardia (VT) refractory to treatment with rest, anti-inflammatory drugs, lidocaine, or procainamide were treated with phenytoin sodium p.o. q12h. The starting dosage of phenytoin was 20 or 22 mg/kg body weight (BW) q12h, and the maintenance dosage varied from 8 to 17 mg/kg BW q12h. The mean +/- standard deviation therapeutic blood concentration of total phenytoin was 8.8 +/- 2.1 mg/L, and the mean concentration of free phenytoin of 2.5 +/- 0.5 mg/L was relatively constant at a range of 24 to 29% of the total phenytoin concentration. In all horses, both VES and VT were abolished after treatment with phenytoin. On the basis of the results of this clinical study, the authors propose an initial dose of 20 mg/kg BW q12h for the first 3 or 4 dosages, followed by a maintenance dose of 10 to 15 mg/kg BW q12h. Phenytoin plasma concentrations should be monitored during therapy. High plasma concentrations were associated with adverse effects such as recumbency and excitement. In this study, which included a limited number of diverse patients, phenytoin sodium appeared to be an inexpensive and effective treatment for persistent VES or VT in cases where conventional treatment had failed.     

Heart rate and arrhythmia frequency of normal cats compared to cats with asymptomatic hypertrophic cardiomyopathy

ObjectivesTo compare heart rate and arrhythmia frequency and complexity in a normal population of cats to a population of cats with hypertrophic cardiomyopathy (HCM).Animals17 cats with HCM and 15 cats with normal echocardiograms.MethodsResults for echocardiography, electrocardiography, Doppler blood pressure, and 24-h Holter monitoring were compared between groups.ResultsThere was no difference in heart rate between HCM cats and normal cats regardless of modality used. All (17/17) HCM cats had ventricular arrhythmias (geometric mean 124 complexes/24 h) with 82% (14/17) exhibiting complex arrhythmias (couplets, triplets, or ventricular tachycardia). Most (14/15) normal cats had ventricular arrhythmias (geometric mean 4 complexes/24 h), but only 20% (3/15) exhibited complexity. HCM cats had significantly more total ventricular complexes, ventricular premature complexes and accelerated idioventricular rhythm than normal cats (P < 0.0001, P < 0.0001, and P = 0.01, respectively). Eighty eight percent (15/17) of HCM cats had supraventricular arrhythmias (geometric mean 9 complexes/24 h) with 23% (4/17) exhibiting complexity. Sixty percent (9/15) of normal cats had supraventricular arrhythmias (geometric mean 1 complex/24 h) with 13% (2/15) exhibiting complexity. Cats with hypertrophic cardiomyopathy had significantly more supraventricular complexes than normal cats (P = 0.0148).ConclusionCats with asymptomatic HCM have more frequent and complex ventricular and supraventricular arrhythmias than normal cats but do not have different overall heart rates compared to normal cats. Further studies are needed to determine if these arrhythmias are associated with an increased risk of sudden cardiac death or influence long-term survival.     

Effects of acute gastric distention and recovery on tendency for ventricular arrhythmia in dogs

The gastric distention-volvulus (GDV) syndrome occurs commonly in large-breed dogs and may prove fatal in 15-68% of cases. Approximately 43% of cases with gastric distention (GD) or volvulus develop cardiac arrhythmias that can contribute to mortality. Most of these arrhythmias are ventricular in origin and ventricular fibrillation (VF) may be the cause of death. This study used an iatrogenic model of acute GD to investigate the prevalence of ventricular arrhythmias during acute GD and its recovery, if programmed electrical stimulation (PES) may uncover tendency to VF, if the Q-T interval corrected for heart rate (Q-Tc) of the electrocardiogram (ECG) predicts tendency to VF, and if hemodynamic changes predate VF. Eleven beagles, anesthetized with morphine and alpha-chloralose, and instrumented so that vascular pressures, cardiac output, and PES could be recorded, were used. Five were unperturbed, whereas acute GD to a pressure of 30 mm Hg for 1.5 hours was produced in 6 others. The results were as follows. No dogs with GD developed spontaneously occurring arrhythmias. VF was produced in no dogs by conventional PES, but occurred in all dogs (P < .05) with GD and none of the controls, using accelerated ventricular pacing. The Q-Tc interval of the ECG prolonged minimally in dogs with GD, and shortened (P < .05) in controls. Some hemodynamic changes did predate VF. In conclusion, dogs with acute GD have a tendency for VF, which may be uncovered by accelerated PES. The mechanism for the vulnerability to arrhythmia with GD is unknown.     

Transcatheter closure of aneurysmal perimembranous ventricular septal defect with the canine duct occluder in two dogs

Congenital membranous ventricular septal aneurysm has been reported in dogs and can be associated with a perimembranous ventricular septal defect (VSD). The windsock-like ventricular septal aneurysm is formed by tissue of the membranous ventricular septum and portions of the septal leaflet of the tricuspid valve. We report two dogs that underwent transcatheter closure of perimembranous VSD associated with membranous ventricular septal aneurysm using a commercial device marketed for transcatheter closure of patent ductus arteriosus, the canine duct occluder. Partial closure was achieved in the first dog with reduction in left heart dimensions documented on echocardiography both at one day and nine months after procedure. In the second dog, three-dimensional transesophageal echocardiography, cardiac computed tomography, and a three-dimensionally printed whole heart model were used to evaluate feasibility for transcatheter device closure. Complete closure of the VSD was subsequently achieved. Both cases had good short- to medium-term outcomes, no perioperative complications were observed, and both dogs are apparently healthy and receiving no cardiac medications at 34 months and 17 months after procedure. Transcatheter attenuation of perimembranous VSD with membranous ventricular septal aneurysm is clinically feasible using the canine duct occluder, and multimodal cardiac imaging allows accurate assessment and planning prior to transcatheter intervention for structural heart disease in dogs.     

Carvedilol in dogs with dilated cardiomyopathy

BACKGROUND: Dilated cardiomyopathy (DCM) is characterized by reduced systolic function, heightened sympathetic tone, and high morbidity and mortality. Little is known regarding the safety and efficacy of beta-blocker treatment in dogs with DCM. HYPOTHESIS: Carvedilol improves echocardiographic and neurohormonal variables in dogs with DCM over a 4-month treatment period. METHODS: Prospective, placebo-controlled, double-blinded randomized study. Dogs with DCM underwent echocardiography, ECG, thoracic radiographs, and neurohormonal profiling, followed by titration onto carvedilol (0.3 mg/kg q12h) or placebo over a 4-week period and subsequently received 3 months of therapy. Primary study endpoints included left ventricular volume and function. RESULTS: Sixteen dogs received carvedilol and 7 received placebo. At study end, 13 carvedilol dogs and 5 placebo dogs were alive. There was no difference in the mean percentage change in left ventricular volume at end-diastole (LVVd), left ventricular end-systolic volume (LVVs), and ejection fraction (EF) between treatment groups, suggesting that both groups experienced similar amounts of disease progression. Carvedilol treatment did not result in significant changes in neurohormonal activation, radiographic heart size, heart rate, or owner perceived quality-of-life. Baseline B-type natriuretic peptide (BNP) predicted dogs in the carvedilol-treated group that maintained or improved their EF over the study duration. CONCLUSIONS AND CLINICAL IMPORTANCE: Carvedilol administration did not improve echocardiographic or neurohormonal indicators of heart function. The lack of effect may be related to severity of disease, carvedilol dose, or brevity of follow-up time. Statistical power of the present study was adversely affected by a high fatality rate in study dogs and small sample size.     

Pacemaker malfunction due to mechanical failure of the lead–header interface

An 8 year old female spayed Boxer dog, diagnosed with concurrent vasovagal syncope and arrhythmogenic right ventricular cardiomyopathy, presented for routine evaluation approximately three months following epicardial pacemaker implantation. Routine device interrogation revealed intermittent loss of ventricular capture and intermittent failure to appropriately sense. Following evaluation of chronic impedance data, failure of the pacemaker lead–header interface or lead conductor fracture was suspected. Radiographic and pacemaker interrogator findings suggested incomplete lead insertion into the device header with intermittent loss of ventricular capture and variable pacemaker sensing. We hypothesize that either the presence of a loose or cross-threaded set screw or operator error at the time of device implantation may have caused this complication. This report details the diagnosis of mechanical failure of the lead–header interface, a complication not previously reported in a veterinary patient.     

Bartonella-associated inflammatory cardiomyopathy in a dog

A 6-year-old, male, mongrel dog was presented for acute onset of dyspnea and cough. At admission, the dog was cachectic and severely depressed. The electrocardiogram showed a sinus rhythm conducted with left bundle truncular branch block and interrupted by frequent multiform ventricular ectopic beats organized in allorhythmias. Thoracic radiographs revealed a marked cardiomegaly with perihilar edema, whereas transthoracic echocardiography revealed a dilated cardiomyopathy with segmental dyskinesis. Furosemide, enalapril, pimobendan, and mexiletine were prescribed, and a Holter was scheduled after resolution of congestive heart failure. Three days later, the dog died suddenly during sleep. Histopathology revealed diffuse myocyte hypertrophy with multifocal hemorrhages, alternating to areas of severe replacement fibrosis and lymphoplasmocytic infiltrates. Immunohystochemistry stains were strongly positive for T-lymphocyte infiltration (CD3) and weakly positive for B-lymphocytes (CD79). Polymerase chain reaction was positive for Bartonella spp. Based on these results, a post-mortem diagnosis of bacterial inflammatory cardiomyopathy was made.     

Natural history of hypertrophic cardiomyopathy and aortic thromboembolism in a family of domestic shorthair cats

A feline domestic shorthair queen and her 3 offspring were all diagnosed with asymptomatic hypertrophic cardiomyopathy (HCM). The family has been followed for 13 years, and 3 cats have died of aortic thromboembolism (ATE). This communication documents the long-term progression of HCM in these cats that presented with mild left ventricular hypertrophy and hyperdynamic systolic ventricular function, developed progressive left atrial enlargement, and eventually resulted in hypodynamic left ventricular systolic function with relative left ventricular chamber dilation at the time of ATE.     

Echocardiographic and radiographic changes associated with systemic hypertension in cats

The purpose of this study was to assess the effects of systemic hypertension (SHT) on echocardiographic and radiographic cardiovascular variables in affected cats compared with healthy geriatric cats. Secondary objectives were to determine whether there were any relationships between these findings and age or systolic blood pressure (SBP). Fifteen healthy cats (>8 years of age with normal SBP) and 15 hypertensive cats (SBP > 180 mm Hg) were studied. Each cat was evaluated for standard echocardiographic parameters and 4 different aortic root dimensions. Seventeen variables were measured from right lateral and dorsoventral radiographic views. Left ventricle wall thickness was greater in the SHT group (5.1 +/- 0.9 mm) than in the healthy cats (4.2 +/- 0.5 mm). Left ventricular hypertrophy in the SHT cats often was not severe, and mean measures were considered normal. Some cats had asymmetrical septal hypertrophy (ASH) in the basilar portion of the septum as determined from the 2-dimensional view of the left ventricular outflow tract. ASH was greater in cats with SHT. Comparisons of the proximal ascending aorta indicated the presence of dilatation in the SHT cats, and comparison of the ascending aorta to the aortic annulus was helpful in differentiating between the 2 groups. The distal aortic root measurements and ratios evaluated by echocardiography were significantly different between the 2 groups of cats (P = .0001) and were significantly correlated with SBP (P = .0001) but not age (P > .3).     

Gerbode type defect and third degree atrioventricular block in association with bacterial endocarditis in a dog

Gerbode type defects are rare left ventricular outflow tract–right atrial communications in people that may be congenital or acquired; they have been reported only once previously in dogs. Acquired forms in humans have been reported secondary to bacterial endocarditis, trauma, and valve replacement surgery, among other causes. We report a case of left ventricular outflow tract to right atrium and right ventricle communications (Gerbode type defect) in association with aortic and tricuspid valve bacterial endocarditis in a geriatric dog. The dog also developed third degree atrioventricular block and had underlying subaortic stenosis. The authors hypothesize that the Gerbode type defect in this case was acquired secondary to invasion and destruction of the membranous interventricular septum due to bacterial endocarditis.     

Echocardiographic reference intervals in healthy UK deerhounds and prevalence of preclinical dilated cardiomyopathy: a prospective,longitudinal study

BackgroundSighthounds have high echocardiographic (ECHO) left ventricular volumes. Establishing robust breed-specific ECHO reference intervals (RI) for screening is important. End-diastolic volume index (EDVI), end-systolic volume index (ESVI) and ejection fraction (EF) reference ranges derived by Simpson's method of discs are not available for deerhounds. The influence of sex or body weight (BW) on left ventricular diameter during diastole (LVDd) and systole (LVDs) has never been reported.ObjectivesProspectively determine ECHO RI and assess prevalence of dilated cardiomyopathy (DCM) in healthy UK deerhounds.AnimalsNinety-nine deerhounds.MethodsDeerhounds scored on ECHO and ECG variables then classified as normal (NORM), equivocal (EQUIV) or affected (AFF) with DCM. Fifty-nine NORM deerhounds used to determine ECHO RI.ResultsPrevalence of DCM was 21.6%. There were significant differences in BW (P<0.001), LVDd (P<0.001) and LVDs (P<0.05) between female and male deerhounds. Cut-off values for EDVI (≥140.2 mL/m²: 79% sensitivity/97% specificity), ESVI (≥71.9 mL/m²: 94.7% sensitivity/94.2% specificity) and EF (≤42.1%: 84.2% sensitivity/92.8% specificity) were proposed to help diagnose DCM. The most reliable ECHO variables to identify AFF dogs were LVDs indexed to BW by allometric scaling and ESVI; one of the least reliable was sphericity index. Ventricular arrhythmias (VA) were identified in 13.6% of the population, with the highest prevalence in AFF deerhounds (42%).ConclusionsPreclinical DCM in deerhounds is common and VA may be associated with DCM. Healthy deerhounds have higher LVDd, LVDs and EDVI compared with other breeds. This study provides ECHO RIs for deerhounds; sex or BW RIs should be used when screening.