Healthy Doberman Pinschers Research Articles

Two-dimensional speckle tracking-derived global longitudinal strain in healthy Doberman Pinschers: method evaluation, variability, and reference values

IntroductionEvaluation of two-dimensional speckle tracking (2D-ST)-derived global longitudinal strain (GLS) in healthy Doberman Pinschers (DP) is essential before it can be used in diseased DP to assess systolic function. To determine feasibility and observer related measurement variability of 2D-ST-derived GLS by use of AutoSTRAIN (AUTO) and 2D Cardiac Performance Analysis (TomTec Imaging Systems GmbH, Unterschleissheim, Germany). Animals, materials, and methodsThis prospective study included 120 healthy, client-owned DP presented for screening evaluation. Global longitudinal strain of the apical four- (GLSA4C), two-, and three-chamber view as well as the average GLS of all three views combined (GLSAV) were determined, compared, and reference values established. Measurement variability was assessed by using intra- and inter-observer coefficient of variation. ResultsA small difference existed for GLSAV (mean + 0.23%; P=0.022) between the two software programs although the determined strain values were similar and positively correlated (r = 0.84; P<0.001). No difference could be found between GLSAV and GLSA4C for AUTO (mean + 0.16%; P=0.228), whereas a difference existed for Cardiac Performance Analysis (mean −0.89% (end-systolic strain) and −0.56% (peak strain), P<0.0001). Software specific reference values were established for GLSAV and GLSA4C. Intra- and inter-observer coefficient of variation revealed very low to low measurement variability, with better results for AUTO. Discussion and conclusionsTwo-dimensional speckle tracking (2D-ST) derived GLS is a feasible technique to assess systolic function with low measurement variability. Whenever possible, GLSAV should be determined, although GLSA4C might be a potential alternative.

Influence of sex on renin-angiotensin-aldosterone system metabolites and enzymes in Doberman Pinschers.

Estrogen modulates the renin-angiotensin-aldosterone system (RAAS) in women, but sex differences have not been fully explored in dogs. We hypothesized that the RAAS profile of intact female (IF) Doberman Pinschers (DP) would differ from spayed female (SF) and intact male (IM) DP. Eighteen healthy DP (6 IF, 6 SF, 6 IM). Absolute and indexed RAAS metabolites, angiotensin-converting enzyme (ACE) and ACE2 activities, and genotypes (pyruvate kinase dehydrogenase 4, titin, and ACE variants) were compared among sex groups using Kruskal-Wallis or chi-square tests, and linear regression controlling for age. Data are expressed as median (minimum, maximum) and P < .05 was considered significant. The ACE activity was higher in IF DP (656 pmol/L; 436, 784) compared to SF DP (411 pmol/L; 287, 451; P=.01) and IM DP (365 pmol/L; 276, 1200; P=.04) after controlling for age. Angiotensin II, angiotensin I, and plasma renin activity marker (PRA-S) were higher in IF DP compared to SF DP, but not significantly (P ≤ .25). After controlling for age, angiotensin 1-7/angiotensin I was lower in IF DP compared to SF DP (P=.01). Genotypes did not differ among groups. Most DP (94%) were ACE variant positive. Sex and reproductive status influenced the RAAS of DP, with IF DP showing genotype-independent higher ACE activity. These findings hold implications for sterilization practices in female dogs, and support sex and reproductive status as a source of variability in RAAS studies. Additionally, the frequency of the ACE gene variant was very high in this group of DP.

Effect of type of diet on blood and plasma taurine concentrations, cardiac biomarkers, and echocardiograms in 4 dog breeds.

BackgroundAssociations of diet with dilated cardiomyopathy are under investigation.ObjectivesThat cardiac assessment would show abnormalities in healthy dogs eating grain‐free (GF) diets or diets with Food and Drug Administration (FDA)‐listed ingredients of concern (peas, lentils, or potatoes) as top 10 ingredients (FDA‐PLP), but not in dogs eating grain‐inclusive (GI) diets or diets without FDA‐listed ingredients of concern (PLP) in the top 10 ingredients (NoFDA‐PLP).AnimalsOne hundred eighty‐eight healthy Doberman Pinschers, Golden Retrievers, Miniature Schnauzers, and Whippets.MethodsThis study was an observational cross‐sectional study. Echocardiograms, cardiac biomarkers, and blood and plasma taurine concentrations were compared between dogs eating GF (n = 26) and GI (n = 162) diets, and between FDA‐PLP (n = 39) and NoFDA‐PLP (n = 149) diets, controlling for age and breed. Demographic characteristics, murmurs, genetic status, and ventricular premature complexes (VPCs) during examination were compared between dogs eating different diet types.ResultsNo differences in echocardiographic variables, N‐terminal pro‐B‐type natriuretic peptide or whole blood taurine were noted between dogs eating different diet types. Dogs eating GF diets had higher median high‐sensitivity cardiac troponin I (hs‐cTnI) (GF 0.076 ng/mL [Interquartile range (IQR), 0.028‐0.156] vs. GI 0.048 [IQR, 0.0026‐0.080]; P < .001) and higher median plasma taurine (GF 125 nmol/mL [IQR, 101‐148] vs GI 104 [IQR, 86‐123]; P = .02) than dogs eating GI diets. Dogs eating FDA‐PLP diets had higher median hs‐cTnI (0.059 ng/mL [IQR, 0.028‐0.122]) than dogs eating NoFDA‐PLP diets (0.048 [IQR, 0.025‐0.085]; P = .006). A greater proportion of dogs eating FDA‐PLP diets (10%) had VPCs than dogs eating NoFDA‐PLP diets (2%; P = .04).Conclusions and Clinical ImportanceHigher hs‐cTnI in healthy dogs eating GF and FDA‐PLP diets might indicate low‐level cardiomyocyte injury.

The prevalence of atrial premature complexes in healthy Doberman Pinschers and their role in the diagnosis of occult dilated cardiomyopathy

The importance of atrial premature complexes (APCs) as a possible marker of occult dilated cardiomyopathy (DCM) in Doberman Pinschers (DP) is unknown. The aim of this study was to identify APC in healthy DP and to investigate their role as early markers of occult DCM. Holter-ECG results from 561 examinations of 153 DP at different time points were retrospectively evaluated, with special emphasis on APCs. Holter results from 110 healthy control DPs were compared to the last normal Holter and echocardiographic examinations in 43 DP that subsequently developed DCM within 15 months (DCM group), and to the first examination in the DCM group that contained ventricular premature complexes (VPC).There were no significant differences in the number of APCs or the coupling interval between the control group and the last normal examination in the DCM group (P > 0.05). The number of APCs increased slightly at the first abnormal examination in the DCM group. Healthy male DP had more APCs than females (P = 0.009) and older dogs had APCs more frequently than younger dogs (P < 0.001). About 85% of healthy DP with at least one APC/24 h had <20 APCs/24 h. Extracardiac diseases, especially gastrointestinal diseases influenced the occurrence of APCs (P = 0.037 and P = 0.006, respectively). APCs were present without obvious cardiac disease and were not a marker for the development of DCM, as they were not identified until after VPCs were present.

Left shift of the ventricular mean electrical axis in healthy Doberman Pinschers.

In canine electrocardiography, the reference interval of the ventricular mean electrical axis (MEA) is between +40° and +100°. MEA values in dogs can be influenced by the patient position as well as by the shape of the thorax. The aim of this study was to evaluate the MEA in healthy Doberman Pinschers, hypothesizing that some present a left shift of the MEA. In this retrospective study, 41 healthy, client-owned Doberman Pinschers were included. Echocardiography and standard six-lead ECG examination were performed in all dogs. The MEA was calculated using the isoelectric method. The morphology of the QRS complex and the Q/R ratio in lead II were also evaluated. The median MEA was +45° and ranged from −45° to +90°. MEA was deviated in 16/41 dogs (39%), all presenting a left axis deviation (range, −45° to + 30°). Age was significantly associated with the MEA (P=0.008), showing a negative linear correlation. A deep Q wave in lead II was present in 26/41 (63%) dogs. The Q/R ratio was higher in dogs presenting left shift of the MEA (0.66; range, 0.28–1.35) in comparison to dogs with a MEA within reference range (0.44; range, 0.04–0.73; P<0.001). In conclusion, a significant number of healthy Doberman Pinschers present a left shift of the MEA compare to the reference range, and dogs with MEA deviation show a higher Q/R ratio in lead II. This data should be considered when electrocardiographic evaluation is performed in Doberman Pinschers.

Heart rate turbulence after ventricular premature beats in healthy Doberman pinschers and those with dilated cardiomyopathy

ObjectivesTo describe the measurement of heart rate turbulence (HRT) after ventricular premature beats and compare HRT in healthy Doberman pinschers and those with dilated cardiomyopathy (DCM), with and without congestive heart failure (CHF). AnimalsSixty-five client-owned Dobermans: 20 healthy (NORMAL), 31 with preclinical DCM and 14 with DCM and CHF (DCM + CHF). MethodsA retrospective study of data retrieved from clinical records and ambulatory ECG (Holter) archives, including data collected previously for a large-scale prospective study of Dobermans with preclinical DCM. Holter data were reanalysed quantitatively, including conventional time-domain heart rate variability and the HRT parameters turbulence onset and turbulence slope. ResultsHeart rate turbulence could be measured in 58/65 dogs. Six Holter recordings had inadequate ventricular premature contractions (VPCs) and one exhibited VPCs too similar to sinus morphology. Heart rate turbulence parameter, turbulence onset, was significantly reduced in DCM dogs, whereas conventional heart rate variability measures were not. Heart rate variability and HRT markers were reduced in DCM + CHF dogs as expected. ConclusionsHeart rate turbulence can be measured from the majority of good quality standard canine 24-hour Holter recordings with >5 VPCs. Turbulence onset is significantly reduced in Dobermans with preclinical DCM which indicates vagal withdrawal early in the course of disease. Heart rate turbulence is a powerful prognostic indicator in human cardiac disease which can be measured from standard 24-hour ambulatory ECG (Holter) recordings using appropriate computer software. Further studies are warranted to assess whether HRT may be of prognostic value in dogs with preclinical DCM and in other canine cardiac disease.

Assessment of mechanical ventricular synchrony in Doberman Pinschers with dilated cardiomyopathy

Objectives Loss of temporal synchrony of myocardial contraction has been shown to reduce systolic function and be responsible for disease progression in people. The objective of this study is the assessment of inter- and intra ventricular synchrony in healthy Doberman Pinschers and those with dilated cardiomyopathy (DCM) by use of conventional Doppler and tissue velocity imaging. Animals A total of 60 scans from 35 client-owned Doberman Pinschers presented for cardiac evaluation were analysed. Methods Retrospective analysis of data. Using the European Society of Veterinary Cardiology DCM taskforce scoring system, Doberman Pinschers were classified into 4 groups: Control (Group 1; n = 12), depressed systolic function other than DCM (Group 2; n = 9), preclinical DCM (Group 3; n = 8) and symptomatic DCM (Group 4; n = 6). The time intervals between the beginning of the QRS complex and the peak velocity of pulmonic flow (Q-P) and the peak aortic flow (Q-Ao) were used to assess global synchrony between both ventricles. The time intervals between the beginning of the QRS complex and the peak myocardial systolic velocity (Q-peak S) and the onset of myocardial systolic velocity (Q-start S) were measured at the base of the right and left ventricular free wall (RVFW and LVFW) and interventricular septum (IVS), and used to determine segmental longitudinal inter- and intra ventricular synchrony. Results No significant loss of global or segmental longitudinal inter- or intra ventricular synchrony was identified between the groups. Conclusion Impairment of longitudinal fibre synchrony does not appear to be significantly associated with clinical status of DCM in Doberman Pinschers, although it was identified in certain individuals.

Evaluation of N-terminal pro-B-type natriuretic peptide as a diagnostic marker of various stages of cardiomyopathy in Doberman Pinschers

To evaluate the diagnostic value of plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations in Doberman Pinschers in various stages of dilated cardiomyopathy (DCM). 328 Doberman Pinschers. Staging of DCM was determined via analysis of results of physical examinations, 24-hour ambulatory ECG (Holter) recordings, and echocardiographic evaluations. Plasma samples for NT-proBNP assays were obtained at each examination. Concentrations of NT-proBNP were measured in 337 samples obtained from 196 healthy Doberman Pinschers (control dogs) and in 195 samples obtained from 132 Doberman Pinschers in various stages of DCM. These included dogs that had ventricular premature contractions (VPCs; 79 samples), echocardiographic changes (23 samples), or both (51 samples); 16 samples were from dogs with overt DCM, and 26 were from dogs that were considered normal during initial examination but developed DCM within 1.5 years after this assessment. Receiver operating characteristic curves were analyzed to determine sensitivity and specificity of NT-proBNP concentrations for detection of DCM. NT-proBNP concentrations in dogs that had or developed DCM were significantly higher than those of control dogs. Sensitivity and specificity of NT-proBNP concentrations (cutoff value, > 400 pmol/L) to detect all stages of DCM were 81.1 % and 75.0%, respectively; sensitivity was 90.0% and specificity was 75.0% to predict echocardiographic changes. Specificity to detect echocardiographic changes was 90.4% at a cutoff value of 550 pmol/L. Plasma concentrations of NT-proBNP were increased in dogs with DCM and in apparently healthy dogs that developed DCM within 1.5 years after samples were obtained, compared with concentrations in control dogs.

Color-coded longitudinal interventricular septal tissue velocity imaging, strain and strain rate in healthy Doberman Pinschers

Objective To determine reference values for septal longitudinal tissue Doppler imaging (TDI) in Doberman Pinschers. Background TDI includes several new techniques, such as tissue velocity imaging (TVI), strain, and strain rate that might be used to detect early myocardial dysfunction. However, before these techniques can be used, breed specific reference ranges need to be established. Animals, materials and methods One-hundred healthy Doberman Pinschers ≥ 4 years of age were prospectively evaluated using electrocardiography, Holter recording, and echocardiography. Systolic, early and late diastolic parameters of septal longitudinal color-coded TVI, strain, and strain rate were analyzed in three myocardial segments (basal, middle, and apical). Results TDI was feasible in all Doberman Pinschers. Reference values were established for every myocardial segment. There was a significant velocity gradient from the basal to the apical segment for all TVI parameters. No differences between the three segments were found for systolic strain and strain rate. Several diastolic strain rate values were significantly different between myocardial segments. Influence of age, weight, and gender was not clinically relevant. Conclusions This study provides reference values for TVI, strain, and strain rate in Doberman Pinschers. The parameters established here can be used for a supportive diagnostic approach.

Use of Simpson's Method of Disc to Detect Early Echocardiographic Changes in Doberman Pinschers with Dilated Cardiomyopathy

M-mode is the echocardiographic gold standard to diagnose dilated cardiomyopathy (DCM) in dogs, whereas Simpson's method of discs (SMOD) is the preferred method to detect echocardiographic evidence of disease in humans. To establish reference values for SMOD and to compare those with M-mode measurements. Nine hundred and sixty-nine examinations of 471 Doberman Pinschers. Using a prospective longitudinal study design. Reference values for SMOD were established using 75 healthy Doberman Pinschers >8 years old with <50 ventricular premature contractions (VPCs) in 24 hours. The ability of the new SMOD cut-off values, normalized to body surface area (BSA), for left ventricular end-diastolic volume (LVEDV/BSA >95mL/m(2) ) and end-systolic volume (LVESV/BSA > 55mL/m(2) ) to detect echocardiographic changes in Doberman Pinschers with DCM was compared with currently recommended M-mode values. Dogs with elevated SMOD values but normal M-mode measurements were followed-up using a prospective longitudinal study design. At the final examination 175 dogs were diagnosed with DCM according to both methods (M-mode and SMOD). At previous examinations, M-mode values were abnormal in 142 examinations only, whereas all 175 SMOD already had detected changes. Additionally, 19 of 154 dogs with >100 VPCs/24 hours and normal M-mode values had abnormal SMOD measurement. Six dogs with increased SMOD measurements remained healthy at several follow-up examinations (classified as false positive); in 24 dogs with increased SMOD measurements, no follow-up examinations were available (classified as unclear). SMOD measurements are superior to M-mode to detect early echocardiographic changes in Dobermans with occult DCM.

Influence of antiarrhythmia therapy on survival times of 19 clinically healthy Doberman pinschers with dilated cardiomyopathy that experienced syncope, ventricular tachycardia, and sudden death (1985-1998).

Overtly healthy Doberman pinschers, having moderate to severe myocardial failure secondary to dilated cardiomyopathy, which experienced ventricular tachycardia, syncope or collapse, and sudden death were studied to determine the effect of antiarrhythmic medication on their clinical outcome. Antiarrhythmia drug therapy may have retarded sudden death in 13 treated dogs compared to the six dogs not administered antiarrhythmia drugs.

Evaluation of stability over time for measures of heart-rate variability in overtly healthy Doberman Pinschers

To determine whether results of analysis of heart-rate variability (HRV) in overtly healthy Doberman Pinschers remain stable over time. 24 overtly healthy client-owned Doberman Pinschers. The HRV was analyzed in time- and frequency-domains from 24-hour ambulatory electrocardiographic (Holter) monitor recordings. Activity during paired tests (tests 1 and 2) was similar (17 dogs) or nearly identical (7). Holter recordings and HRV analyses of those 17 dogs were repeated at a mean +/- SD of 65 +/- 50 weeks (median, 51 weeks; range, 10 to 177 weeks), whereas it was repeated for the other 7 dogs at 3 to 9 weeks (mean, 73 +/- 2.1 weeks). Differences between test 1 and test 2 were not significantly different, except for 24-hour means of the normal beat-to-normal beat (NN) intervals in all 5-minute segments. Strongest correlations were for SD of all NN intervals and root mean square successive difference between adjacent NN intervals of the time-domain analyses and total power, very-low frequency power, and high-frequency power of the frequency-domain analyses. When activity during tests 1 and 2 in 7 dogs was stringently controlled, the differences were not significantly different, and correlation factors for the 24-hour HRV analyses exceeded 0.83. Variables from sequential HRV analyses in overtly healthy Doberman Pinschers with normal echocardiograms are moderately stable when physical activity is not stringently controlled and extremely stable for at least 3 to 9 weeks when physical activity is stringently controlled.

Correlations among time and frequency measures of heart rate variability recorded by use of a Holter monitor in overtly healthy Doberman pinschers with and without echocardiographic evidence of dilated cardiomyopathy.

To determine correlations between time-domain and frequency-domain variables of heart rate variability (HRV) derived from 24-hour recordings obtained by use of an ambulatory electrocardiographic recorder (Holter monitor). 59 overtly healthy Doberman Pinschers (41 without echocardiographic evidence of cardiomyopathy and 18 with precongestive heart failure attributable to cardiomyopathy). The HRV was analyzed from 24-hour recordings. Variables were calculated from the entire 24-hour recording as well as 4 user-selected time epochs. Comparisons were made for total power to SD of normal beat-to-normal-beat (NN) intervals (SDNN), ultra-low frequency power to SD of the means of NN intervals, low-frequency power and very-low-frequency power to mean of the SD of NN intervals, and high-frequency (HF) power to the root mean square successive difference of NN intervals (RMSSD) and percentage of NN intervals that varied from the previous NN interval by > 50 milliseconds (PNN50). 58 of 66 (88%) comparisons revealed significant values, indicating that relationships between variables were not random (r > 0.7 in 41 of 66 [62%)) comparisons). Strong correlations (r > 0.8) were found between the square root of total power and SDNN and between HF power and RMSSD. Time-domain surrogates for variables of frequency-domain analysis variables that correlated in the dogs reported here are the same ones that reportedly correlate in humans. When 24-hour recordings obtained by use of a Holter monitor are used to calculate HRV, SDNN and total power as well as RMSSD and HF power are interchangeable.

Effect of severity of myocardial failure on heart rate variability in Doberman pinschers with and without echocardiographic evidence of dilated cardiomyopathy.

To determine whether heart rate variability (HRV) is reduced in Doberman Pinschers with dilated cardiomyopathy. Case series. 62 overtly healthy Doberman pinschers. Heart rate variability was analyzed in time and frequency domains from data obtained during 24-hour ambulatory electrocardiographic Holter recordings in 41 overtly healthy Doberman pinschers with normal echocardiograms and 21 overtly healthy Doberman pinschers with abnormal echocardiograms. Heart rate variability usually was greater during night versus day, and 2 dogs with the most severe myocardial failure had reduced HRV. Reduced HRV was detected only in Doberman Pinschers with the most severe myocardial failure. Thus, HRV in less severely affected dogs is not reduced, or the normal sinus arrhythmia of dogs renders HRV relatively insensitive. Analysis of HRV did not provide additional information relative to the severity of left ventricular dysfunction or risk of sudden death from that which could be derived from echocardiography, analysis of Holter recordings, and signal-averaged electrocardiography.

Results of ambulatory electrocardiography in overtly healthy Doberman Pinschers with equivocal echocardiographic evidence of dilated cardiomyopathy.

To determine results of ambulatory electrocardiography in and outcome of overtly healthy Doberman Pinschers with equivocal echocardiographic evidence of dilated cardiomyopathy. Case series. 44 overtly healthy (25 male, 19 female) Doberman Pinschers. 24-hour ambulatory electrocardiographic (Holter) recordings with > 90% scan quality obtained the same day that echocardiography was performed were reviewed. Holter recordings from 42 of 44 (95%) dogs contained ventricular premature complexes (VPC). Fifteen of 44 (34%) dogs had > 100 VPC, 9 (20%) had > 500 VPC, and 5 (11%) had > 1,000 VPC. Nonsustained (< 30 seconds) ventricular tachycardia was detected in 4 dogs. Eighteen of 27 (67%) dogs with > 100 VPC, any couplets or triplets of VPC, or ventricular tachycardia developed dilated cardiomyopathy within 1 year, compared with 8 of 17 (47%) dogs with < 100 VPC, no couplets or triplets of VPC, and no ventricular tachycardia. Of the 18 dogs that did not develop dilated cardiomyopathy within 1 year, 11 (61%) did so within 3 years. Results suggest that a high percentage of Doberman Pinschers with equivocal echocardiographic evidence of dilated cardiomyopathy will be found to have VPC during 24-hour ambulatory electrocardiography and that most will develop echocardiographic abnormalities indicative of cardiomyopathy.

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

To identify, by means of 24-hour ambulatory electrocardiography, electrocardiographic abnormalities in overtly healthy Doberman Pinschers in which results of echocardiography were abnormal. Clinical case series. 56 (35 male, 21 female) overtly healthy Doberman Pinschers with echocardiographic evidence of cardiomyopathy on initial examination that subsequently died of cardiomyopathy. Twenty-four-hour ambulatory electrocardiographic (Holter) recordings obtained at the time of initial examination were reviewed. For all dogs, scan quality was > 90%. 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. Results suggested that along with echocardiography, 24-hour ambulatory electrocardiography can be used to help identify overtly healthy Doberman Pinschers with cardiomyopathy.

Association between results of ambulatory electrocardiography and development of cardiomyopathy during long-term follow-up of Doberman pinschers.

To characterize ambulatory electrocardiographic results of overtly healthy Doberman Pinschers and determine associations between those results and development of dilated cardiomyopathy. Cohort study. 114 (58 male, 56 female) overtly healthy Doberman Pinschers without echocardiographic evidence of cardiac disease on initial examination. Echocardiograms and 24-hour ambulatory electrocardiograms (Holter recordings) were obtained initially and at variable intervals. The status (live vs dead) of all dogs was known at least 2 years and as long as 10 years after initial examination (mean [+/- SD] follow-up time, 4.33 +/- 1.84 years). Associations between development of dilated cardiomyopathy and number of ventricular premature contractions (VPC), age, and sex were determined. 55 dogs (48%) did not have VPC on initial Holter recordings, and only 8 dogs had > 50 VPC/24 hours. The likelihood that a dog would have VPC was associated with increasing age and being male. At least 1 VPC/24 hours, and in particular, > 50 VPC/24 hours or > or = 1 couplet or triplet of VPC/24 hours, were predictive of subsequent development of dilated cardiomyopathy. Fifty-four dogs (47%) developed dilated cardiomyopathy; 12 were still alive at the end of the study, and 42 had died. Twenty-five of these 42 dogs died after the onset of congestive heart failure (CHF), 15 died suddenly before the onset of overt CHF, and 2 died of noncardiac causes. More males developed dilated cardiomyopathy than females, and dogs that died suddenly were approximately 1 year younger than those that developed CHF. Results of high-quality Holter recordings may be used to identify overtly healthy Doberman Pinschers that are at a high risk for dilated cardiomyopathy.

Resting and dobutamine stress echocardiographic factors associated with the development of occult dilated cardiomyopathy in healthy Doberman pinscher dogs.

In 29 healthy Doberman Pinschers, echocardiographic parameters evaluating systolic and diastolic function were examined prospectively at rest and during dobutamine constant rate infusion (5 micrograms/kg/minute) to determine if any parameters were associated with the development of occult dilated cardiomyopathy (DCM). A resting echocardiogram was repeated 1 year later to determine which dogs had met our criteria for occult DCM. Six dogs developed occult DCM during the follow-up period. Univariate logistic regression analysis showed that at rest, an increased left ventricular internal dimension in systole (LVID-S) (P = .02), preejection period (PEP) (P = .03), ratio of PEP to left ventricular ejection time (P = .02), and isovolumic relaxation time (P = .02) were significantly associated with the development of occult DCM. During dobutamine stress echocardiography (DSE), high LVID-S (P = .02) and systolic wall stress index (P = .04) and reduced fractional shortening (P = .02) and ratio of peak early to late diastolic mitral filling velocity (E/A) (P = .05) were associated with the development of occult DCM. Multiple logistic regression showed that LVID-S (P = .002) and E/A (P = .002) measured during dobutamine infusion also were associated with the development of occult DCM. Reclassification based on the DSE data was not significantly different than reclassification based on the resting echocardiographic data. Resting echocardiography and DSE have the potential to be clinically applicable screening tests for very early systolic and diastolic dysfunction in Doberman Pinschers, heralding the onset of occult DCM as it is currently defined.

Naturally occurring cardiomyopathy in the Doberman pinscher: A possible large animal model of human cardiomyopathy?

Currently there is no large animal model of dilated cardiomyopathy. The smaller animal models of cardiomyopathy, such as the Syrian hamster, cannot be studied with echocartography and cardiac catheterization, and the relevance of these models to human dilated cardiomyopathy is open to question. On the basis of some initial observations in Doberman pinschers, it was speculated that these dogs could have occult left ventricular dysfunction. Accordingly, studies were performed in 46 apparently healthy Doberman pinschers and in 41 mongrel dogs: two-dimensional echocardiography (30 dogs in each group), cardiac catheterization (16 Doberman pinschers and 12 mongrels) and coronary blood flow studies (13 Doberman pinschers and 6 mongrels). In the awake, unsedated dogs studied with echocardiography, left ventricular wall thickening was significantly less in the Dobermans than in the mongrels (28% versus 36%, p = 0.0003). In the anesthetized dogs undergoing cardiac catheterization, left ventricular ejection fraction was significantly lower in the Dobermans than in the mongrels (0.38 versus 0.63, p = 0.0001). Rest coronary blood flow and coronary blood flow reserve were similar in the two groups.It is concluded that apparently healthy Doberman pinschers have occult left ventricular dysfunction. These dogs may serve as a large animal model of dilated cardiomyopathy and should not be used experimentally to study normal cardiac physiology.