The standardized cardiac examination of the dog with … · S. Schlieter, C. Schmidt, I. Schneider,...

Tierärztliche Praxis Kleintiere 4/2012; 40(K): 283–289

1 © Schattauer 2012Recommendations

The standardized cardiac examination of the dog with centralized entry and collection of data of the Collegium Cardiologicum (CC) (registered association) M. Deinert; M. Janthur; J. G. Kresken; M. Schneider; R. Tobias; R. Wendt* Collegium Cardiologicum (CC) e. V.

Correspondence to Dr. M. Deinert Tierklinik Am Sandpfad, Dr. Walla & Partner Ludwig-Wagner-Straße 31 69168 Wiesloch Germany Email: [email protected]

Standardisierter kardiologischer Untersuchungsgang beim Hund mit zentraler Datenerfassung des Collegium Cardiologicum (CC) e. V. (English version of) Tierärztl Prax 2012; 40 (K): 283–289 Received: July 2, 2012 Accepted: July 2, 2012

Introduction

Due to the increased incidence of heart disease in purebred dogs (i.e. [12]), cardiac examination has been recommended for breed-ing dogs and their offspring since the early 1980s (e.g. decision of the „Boxer Club Munich e.V.“ regarding cardiological suitability for breeding). However, this practice of screening for heart disease has highlighted a number of important questions, such as what are the most appropriate cardiac examination techniques, at what age should cardiac screening start, what should the interval between examinations be, what is the prospective significance of the screen-ing results, what is the genetic influence, what are the consequences for breeders and their breeding programmes, and which individu-als of the veterinary profession are best qualified to perform these examinations.

The ongoing debate as to which institution would evaluate and certify the qualifications in small animal cardiology and approve breeding suitability of dogs for the numerous breed clubs, was re-solved with the establishment of the Collegium Cardiologicum (CC) in 2003 (www.collegium-cardiologicum.de). The CC was modelled on the Association of Veterinary Ophthalmologists in the DOK (Association for Diagnosis of ophthalmologic diseases with genetic origin, registered association) (5). The „CC e.V.“ has more than 35 certified specialist members, and organizes Mem -bers‘ Meetings once a year according to guidelines of the Asso -ciation as well as an additional annual Meeting.

Therefore, the „CC e.V.“ has the following functions: 1. Examination and quality assurance of the cardiological qualifi-

cations of members 2. Development of a standardized cardiac examination method,

especially with reference to hereditary heart disease in purebred dogs and cats

3. Standardization and central registration of recorded data 4. Providing advice to breed associations, in collaboration with

geneticists, based on the data gathered and recorded

Cardiological examination profile

Conditions such as hip dysplasia are screened for using the cen -tralized expert assessment of standard radiographs. However, this method of centralized expert assessment is not used for cardiac screening, meaning that the veterinary surgeon performing the cardiac examination must also assume the function of an expert witness. Therefore it is vitally important that the data recording and interpretation by each examiner should be standardized for quality assurance. In addition to the clinical cardiac examination, echocardiography (9) is the most important diagnostic tool to de-tect structural and functional heart disease. Short and long-term ECG monitoring is an important additional diagnostic tool for evaluation of arrhythmias in the patient (3, 14).

The quality of echocardiographic examination depends on the experience and expertise of the examiner, which naturally leads to certain discrepancies. Also, a minimal reproducible variation may occur within echocardiographic measurements of the same exa -miner and patient (measuring tolerance). Another consideration is that echocardiographically measurable parameters of the heart, which is a complex, mobile, fluid-filled organ, are influenced and constantly changed by factors such as heart rate, filling pressures, haemodynamic status, as well as pharmacologic agents. Further -more, there are several studies with different methodology re -garding echocardiographic characteristics such as ventricular size and function, flow rate, etc. This results in variations of examiner preferences (6).

* Additional authors: all members of the CC e. V. (in alphabetical order): G. Eichhorn, R. J. Gerritsen, O. Godfroy, E. Grußendorf, E. Henrich, N. Hil-debrandt, R. Höpfner, A. Hörauf, A. Huettig, P. Kattinger, L. Keller, M. Kil -lich, A. Kirsch, U. Klein, E. Lohss-Baumgärtner, I. März, M. Markovic, A. Mischke, P. Modler, C. Poulsen Nautrup, S. Riesen, J. Schiele, S. Schiller, S. Schlieter, C. Schmidt, I. Schneider, R. Schramm, M. Skrodzki, A. Vollmar, M. Wehner, G. Wess.

M. Deinert et al.: The standardized cardiac examination of the dog 2

Tierärztliche Praxis Kleintiere 4/2012; 40(K): 283–289 © Schattauer 2012

Subsequent analyses are based on data recorded by examiners of the „CC e.V.“, therefore defining a uniform and obligatory examin-ation profile is a necessity. The aim of this article is to present the standardized cardiac examination for the dog, as currently recom-mended by the „CC e.V.“

History of the examination profile

Since the Cardiology Group was first founded in 1988 within the „DGK-DVG“ (German Society for Small Animal Veterinary Me -dicine), the cardiac examination method has been a point of dis-cussion. This was initiated by the examination series to further define stenoses in the outflow tract of Boxers in Germany, arranged by the „Boxer Club Munich“. The basic concept applied was taken from the examination method recommended by the Justus Liebig University in Giessen for the examination series mentioned pre-viously. Furthermore, an examination profile for the Irish Wolf-hound with reference values already existed (13).

Within the context of the first practical exam of the „CC e.V.“ in the year 2004 in Bielefeld, the executive committee recorded the examination profiles of colleagues (C. Poulsen-Nautrup, M. Schneider, M. Skrodzki, R. Tobias, A. Vollmar) who would later form the examination board. This was the first outline for a general profile.

During an annual meeting of the „CC e.V.“ in Bad Nauheim (2008), all CC-Members participated in a ballot to decide on the standardized cardiac examination method. Since this ballot, the resulting method, as well as the reported findings (�Fig. 1), are binding within the „CC e.V.“ for the pre-breeding cardiac examin-ation of the dog.

Examination request, basic data, signalment and identification of dogs

Similar to the pre-purchase examination, the cardiac pre-breeding examination has an important medical and forensic purpose. Therefore, specific requirements for documentation of the request and patient indentification data, as well as findings are needed.

Standard information about the breeding dog are recorded such as name and address of owner, kennel name of dog, breed, coat colour (in certain breeds), name of breed association, regis-tration number, age, sex, weight, microchip and/or tattoo number and whether it is an initial examination or a re-examination.

Once the examiner has confirmed the identity of the dog pres-ented for pre-breeding cardiac screening, the owner must give his signed consent for the examination to take place, for transmission of results to the CC data base, the breed association and for data publication.

Each examination is assigned a unique number. Each examiner is also assigned a specific identification number. To date, the CC

has a data base comprising over 5500 cardiac examinations from various breeds of dogs.

Details of the examination profile

Clinical findings

Only asymptomatic dogs should undergo a cardiac pre-breeding examination. The owner must sign the form to confirm that the dog is not receiving any cardiovascular medications. Any addi-tional information is included in the request form under the point Comments and based on this information, further examinations may be deemed necessary. The reason being that cardiac findings of dogs with internal disease may be questioned retrospectively, in relation to their pre-breeding significance. Sedation is not per-mitted for the pre-breeding examination, and is not recommended for other cardiac examinations.

The clinical examination consists of a general as well as a car -diac examination. The pulse rate as well as auscultatory findings must be documented. Heart murmurs should be graded on a scale of 1 to 6 and classified as systolic, diastolic or continuous.

Echocardiographic measurements and findings

A medical ultrasound machine with echocardiographic capabil-ities should be used. The ultrasound machine must have the fol-lowing features: continuous wave, pulsed wave and colour flow Doppler, simultaneous EKG, ability to record and play-back both single frames and loops, cardiac probes with a frequency range be-tween 2.0 and 7.5 MHz. To display the aorta subcostally in large breed dogs, a low frequency probe is needed.

The specific order of acquiring the echocardiographic mea -surements is left up to the individual examiner. However, the echo -cardiographc examination typically begins parasternally on the left side with the four-chamber view. A concurrent EKG is a pre-requisite for the correct timing of measurements as well as systolic time intervals. All measurements should be documented in milli-meters (mm), time intervals in milliseconds (ms) and flow rates in meters per second (m/s).

The examination is documented by recording still frames and videos. In the process, a video sequence of relevant sectional planes and pathological changes should be made from 2D frames as well as colour-Doppler frames. This documentation not only stands for pathological changes, but also as proof of physiologic conditions.

2D- and M-mode-measurements from the right parasternal view

The measurement of the left atrial diameter from the right para-sternal long axis four-chamber view is documented un der 2D (B-Mode) longitudinal axis LAs in the report form. The measure-

3 M. Deinert et al.: The standardized cardiac examination of the dog

© Schattauer 2012 Tierärztliche Praxis Kleintiere 4/2012; 40(K): 283–289

Fig. 1 Current version of the cardiovascular examination report of the CC e.V. for the dog.

Abb. 1 Befundbogen des CC e. V. für den kardiologischen Untersuchungsgang des Hundes, wie er zum Zeitpunkt der Drucklegung des Artikels online für die Datenbank vorlag



ment should be made using the inner edge method, in end-dias -tole at the time point of maximal atrial filling, and parallel to the mitral annular ring, across the widest part of the left atrium (�Fig. 2).

The measurement of the left atrium and aorta from the right parasternal long axis five-chamber view is documented as a M-mode measurement under LAs and AOd. It should be made so that the M-mode cursor cuts through the longitudinal axis of the aorta at the level of the midpoint echo of the aortic valve (2). For this particular measurement, the leading edge method is used (�Fig. 3).

From this M-mode view the systolic time intervals of the pree-jection period (PEP) and left ventricular ejection time (LVET) are determined. This requires good visualization of aortic valve mo-tion as well as a clear EKG trace. For this step it is recommended that the sweep speed of the M-mode is adjusted for the heart rate, as this will increase the accuracy. Measurement of PEP starts with the QRS-complex and ends with the opening of the aortic valve. The LVET begins with the end of the PEP interval and ends with the closing of the aortic valve. Measurements are documented in milliseconds under M-Mode. PEP/LVET is without dimension (1) (�Fig. 3).

The third measurement of the left atrium is obtained from the short axis (4). The aorta is cut vertically at the level of the aortic valve, so that each cusp of the semilunar valve is visible. The measurement is taken at the beginning of diastole, using the first frame with a closed aortic valve. The measurement is made from the midpoint of the convex curvature of the right coronary cusp to the valve commissure situated directly opposite. The cursor should be positioned as close as possible to the blood-tissue border (inner edge). To complete this measurement, within the same time frame, the left atrial diameter is measured by extension of this line to the opposite left atrial parietal wall. Again, the inner edge method is used. This is how the LA : Ao ratio is calculated. The results are documented under 2D (B-Mode) SA (short axis), (�Fig. 4).

The M-mode measurements of the left ventricle, i.e. the thick-ness of myocardium and the internal left ventricular chamber dia meter in systole and diastole, are also documented under M-Mode. It is optional whether the measurement is recorded from the short-axis view (at the level of the tips of the papillary muscles) or the long-axis view (using the four-chamber view, and measur-ing between the tips of the papillary muscles and the mitral valve). The view used to make the measurement must however be docu-mented on the examination sheet. The diastolic measurements are made at the beginning of the QRS complex, and the systolic measurements are made at the point where there is the shortest distance between septum and the left ventricular free wall. The leading edge method should be used. The average value of three consecutive measurements should be recorded. With this infor -mation, the ultrasound machine software should be able to calcu-late the FS (fractional shortening %) and EF (ejection fraction %), as well as EDVI and ESVI (in ml/m2). Currently, the calculation of the left ventricular volume uses the Teichholz's M-mode formula. However, this me thod may be altered in the future depending on results of clinical studies in this area. The purpose of obtaining the left ventricular volume is for additional information only, and is not used as the basis for the final interpretation (�Fig. 5).

The EPSS value is documented under M-Mode. It measures the distance between the E-point of the septal mitral leaflet and the endocardial border of the interventricular septum in diastole. The measurement is made in the right parasternal long axis four-chamber view (�Fig. 6).

Fig. 2 Measurement of the maximal left atrial dimension (LA) from a right-parasternal four-chamber view.

Abb. 2 Messung des maximalen Durchmessers des linken Atriums (LA) im Vier-Kammer-Blick von rechts

Fig. 3 Measurement of left atrial and aortic dimensions in M-mode five-chamber view (long vertical lines) as well as of the systolic time intervals preejection-period (PEP) and left-ventricular ejection-time (LVET) (time inter-vals between the short vertical lines).

Abb. 3 Messung von linkem Atrium und Aorta im M-Mode im Fünf-Kammer-Blick (lange senkrechte Linien) und Messung der systolischen Zeit-intervalle Präejektionsperiode (PEP) und linksventrikuläre Ejektionszeit (LVET) (Zeitintervalle zwischen den kurzen senkrechten Linien)



Doppler-measurements

To exclude congenital defects and pathological flow profiles, a thorough examination in colour Doppler in all sectional planes should be documented. This is primarily to rule out intra- or ex tracardiac shunts, valvular insufficiencies, valvular stenoses (in-cluding sub- or supravalvular stenoses).

Quantitative Doppler-measurements The measurement of the maximal flow rate (Vmax) can be obtained from two positions so that four flow rates can be documented. The right ventricular outflow tract/pulmonic outflow is measured parasternally from the right parasternal short axis view and the left cranial view; the left ventricular outflow tract/aortic outflow is measured from the left apical five-chamber view. The alignment

for flow interrogation using CW Doppler should be parallel with the blood flow, as the use of angle correction is not permitted.

When interrogating the right ventricular outflow tract/pulmo -nic outflow, the Doppler location which gives the highest (Vmax) is definitive. Both flow rates are documented in the recorded frames, but the highest flow rate must be recorded in the report form. When interrogating the left ventricular outflow tract/aortic out-flow, the decisive measurement is made from the subcostal posi-tion. If this is not possible, the left apical measurement can be documented.

The flow profile (laminar or turbulent) is examined in three locations, subvalvular in the outflow tract, valvular at the level of the valve annulus and supravalvular (before the bifurcation of the pulmonary artery or ascending aorta. For this step, colour flow Doppler as well as PW-Doppler should be used in combination (i.e. the „flow mapping“ technique). All findings should be docu-mented as recorded frames.

Insufficiencies of the semilunar valves are recorded on the re-port form semi-quantitatively in three grades. The interpretation is based on expansion of the colour jet in relation to the valvular ring diameter to the longitudinal dimension of the ventricle and on the intensity of the CW signal in relation to the outflow signal (10). Mild pulmonic insufficiencies should be documented in re -corded frames but not on the report form because of the clinical insignificance of this finding in dogs. In contrast, mild aortic insuf-ficiencies should be recorded on the report form. Macroscopic changes in the region of both outflow tracts/semilunar valves are

Fig. 4 Measurement of left atrial and aortic dimensions in the short-axis view.

Abb. 4 Messung von linkem Atrium und Aorta in der kurzen Achse

Fig. 6 Measurement of the EPPS from a right-parasternal four-chamber view.

Abb. 6 Messung des EPSS-Werts im Vier-Kammer-Blick von rechts para-sternal

Fig. 5 Measurement of diastolic and systolic dimensions of the interven-tricular septum, left ventricle and left ventricular free wall in M-mode.

Abb. 5 Diastolische und systolische Messung des interventrikulären Sep-tums, des linksventrikulären Durchmessers und der freien Wand im M-Mode



subjectively interpreted and recorded as present or absent. A de-scription of the stenosis type (subvalvular, valvular) is recorded under the point Congenital Heart Diseases. Furthermore, under Comments , the changes can be described or a subvalvular stenosis can be mentioned. Stenoses are divided in four grades: 0: no ste -nosis, 1: transient finding, and 2–4: mild, moderate and severe stenoses. Transient findings should be defined as breed specific. 3.5–4.5 m/s are considered the reference velocity range for a mo -derate stenosis, provided that the ventricular function is regarded as normal.

Semiquantification of AV-valve insufficiencies The semiquantitative classification of AV-valve insufficiencies into three degrees is made by expansion of the colour flow Doppler jet in relation to the area of the left atrium. Quantity, direction and ex-pansion of the jet as well as valve morphology must be recorded under Other. Systolic anterior motion of the mitral valve (SAM) should be recorded. For the measurement of the mitral valve pro-lapse in millimeters, there is a defined methodology and separate recording box on the report form (7). For tricuspid regurgitation, the Vmax of regurgitation should be obtained by CW-Doppler. The echocardiographic position for this measurement is not defined, the examiner must search for the optimal measurement point par-allel to the main direction of the jet.

2D-measurements from the left side

These measurements must take place in the left apical four-chamber view which is optimised for the right heart. The right ventricle at the time point of maximal filling (late diastole) is measured parallel to the tricuspid annular ring at its maximum

diameter in the basal third according to the inner edge method. Similarly, the right atrium at the time point of maximal filling (sys-tolic) is measured parallel to the tricuspid annular ring and vertical to the intra-atrial septum, respectively (8) (�Figs. 7, 8).

Conversely, in the Irish Wolfhound, the reference values (11) were obtained from the right parasternal four-chamber view. This method was included in the report form of the „CC e.V.“ as breed-specific. The right ventricle is measured at maximal diastole below the tricuspid valve annulus. The maximal diameter of the right atrium is measured parallel to the tricuspid annular ring in systole. Both are inner edge measurements (�Figs. 9, 10). The findings are recorded under the point 2D (B-Mode) LA (longitudinal axis).

ECG on the report form

The mean heart rate obtained througout the entire examination period is recorded under the section Sono-ECG. The presence of a sinus rhythm or any arrhythmias should also be recorded, as well as whether the ECG is classified as physiological or pathological. The heart rate to the time point of M-mode measurements of the left ventricle is seperately verified under the point M-mode.

If any abnormality in the sono-ECG is detected, a conventio -nal ECG should be recorded for a minumum of 3 minutes, so that arrhythmias can be recorded. Ventricular and supraventricu lar extrasystoles should be recorded according to frequency (per 3 mi -nutes). Presence of couplets, triplets, or runs of ventricular tachy -cardia (VT) should also be noted. Additionally there is a box on the report form for documentation of atrial fibrillation and bundle branch blocks (LBBB, RBBB) as well as a box for other observa-tions. A 24-hour ECG is recommended if there is any abnormality

Fig. 7 Measurement of the right atrial dimension from a left apical four-chamber view, focused on the right heart.

Abb. 7 Messung des rechten Atriums von einem links apikalen Vier-Kammer-Blick, der für das rechte Herz optimiert ist

Fig. 8 Measurement of the right ventricular dimension from a left apical view (see Fig. 7).

Abb. 8 Messung des rechtsventrikulären Durchmessers von links apikal (vgl. Abb. 7)



in the sono- or normal ECG that is suggestive of an arrythmogenic cardiomyopathy.

Final evaluation

Four severity grades are determined for the final evaluation of car-diovascular abnormalities: Grade 0 = no or minimal, grade 1 = mild, 2 = moderate and 3 = severe cardiovascular abnormalities. In borderline cases, the decision as to which classification grade to choose is left up to the examiner and a recommendation for a re-examination should be made. Re-examination should also be re -commended for breeding animals without detectable cardiovas -cular abnormalities, for at least every 24 months.

Current cardiovascular examination This document depicts the current examination profile and report form. Future changes will be announced on the Homepage of the „CC e.V.“ (www.collegium-cardiologicum.de).

Fig. 9 Measurement of the right atrial dimension in an Irish Wolfhound from a right parasternal view.

Abb. 9 Messung des rechten Atriums bei einem Irischen Wolfshund von rechts parasternal

Fig. 10 Measurement of the right ventricular dimension in an Irish Wolf-hound from a right parasternal view.

Abb. 10 Messung des rechtsventrikulären Durchmessers bei einem Iri -schen Wolfshund von rechts parasternal

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