a topic:
Samoyed State
of Heart
Tricuspid Valve Dysplasia and Subaortic Stenosis
OFA Congenital Cardiac Registry

The purposes of the cardiac registry are:

  • to gather data regarding congenital heart diseases in dogs;
  • to identify which dogs are phenotypically normal prior to use in a breeding program [TOP]
What is considered a phenotypically normal dog?
For the purposes of the OFA cardiac registry, a phenotypically normal dog is currently defined to be:
  • one without a cardiac murmur;
  • or one with an innocent heart murmur that is found to be otherwise normal by virtue of an echocardiographic examination which includes Doppler studies. [TOP]
Examination and Classification
Each dog is to be examined and classified by a veterinarian with expertise in the recognition of canine congenital heart disease in accordance with OFA procedures outlined in the Application and General Instructions.


A certificate and breed registry number will be issued for any dog found to be non-nal at 12 months of age or older. The OFA fee is $ 15.00 and no charge will be made for recertification at a later age. The breed registry number will indicate the age at evaluation and type of examine
(C-Cardiologist, S-Specialist, P-Practitioner).

Provisional Certification
Evaluation of dogs under 12 months of age is possible if requested by the owner. OFA will enter the information in a data bank at a fee of $10.00 for those found to be normal. Full certification, however, requires subsequent examination at 12 months of age or older. The most opportune time to gather this data is at 6-8 weeks of age prior to the puppy's release to the new owner. If an entire (3 or more) litter is registered at the same time there is a $30.00 fee and subsequent registration from a new owner would be $ 1 0. 00. Such provisional certification may be of value to breeders prior to the sale of any dog or for assessment of the breeding potential of a dog. [TOP]

Submit all evaluations
Dogs with congenital heart disease - The veterinarian and owner are encouraged to submit all evaluations, whether normal or abnormal, for the purpose of completeness of data collection and to assist in the analysis of inheritance of important canine congenital heart defects. There is no OFA fee for entering an abnormal evaluation of the heart into the data bank. [TOP]

GENERAL INSTRUCTIONS~ Methods of Examination

Clinical Examination
The clinical cardiac examination should be conducted in a systematic manner. The arterial and venous pulses, mucous membranes, and precordium should be evaluated. Heart rate should be obtained. The clinical examination should be performed by an individual with advanced training in cardiac diagnosis. Board certification by the American College of Veterinary Internal Medicine, Specialty of Cardiology is considered by the American Veterinary Medical Association as the benchmark of clinical proficiency for veterinarians in clinical cardiology, and examination by a Diplomate of this specialty board is recommended. Other veterinarians may be able to perform these examinations, provided they have received advanced training in the subspecialty of congenital heart disease. [TOP]

Cardiac Auscultation -
should be performed in a quiet, distraction-free environment. The animal should be standing and restrained, but sedative drugs should be avoided. Panting must be controlled, and if necessary, the dog should be given time to rest and acclimate to the environment. The clinician should be able to identify the cardiac valve areas for auscultation. The examiner should gradually move the stethoscope across all valve areas and also should auscultate over the subaortic area, ascending aorta, pulmonary artery, and the left craniodorsal cardiac base. Following examination of the left precordium, the right precordium should be examined. [TOP]
  • The mitral valve area is located over and immediately dorsal to the palpable left apical impulse and is identified by palpation with the tips of the fingers. The stethoscope is then placed over the mitral area and the heart sounds identified.
  • The aortic valve area is dorsal and I or 2 intercostal spaces cranial to the left apical impulse. The second heart sound will be become most intense when the stethoscope is centered over the aortic valve area. Murmurs originating from or radiating to the subaortic area of auscultation are evident immediately candoventral to the aortic valve area. Murmurs originating from or radiating into the ascending aorta will be evident craniodorsal to the aortic valve and may also project to the right cranial thorax and to the carotid arteries in the neck.
  • The pulmonic valve area is ventral and one intercostal space cranial to the aortic valve area. Murmurs originating from or radiating into the main pulmonary artery will be evident dorsal to the pulmonic valve over the left hemithorax.
  • The tricuspid valve area is a relatively large area located on the right hemithorax, opposite and slightly cranial to the mitral valve area.
  • The clinician should also auscultate along the ventral right precordium (right sternal border) and over the right craniodorsal cardiac border.
  • Any cardiac murmurs or abnormal sounds should be noted. Murmurs should be described as indicated below. [TOP]
Description of Cardiac Murmurs -
A full description of the cardiac murmur should be made and recorded in the medical record.
  • Murmurs should be designated as systolic, diastolic, or continuous.
  • The point of maximal murmur intensity should be indicated as described above. When a precordial thrill is palpable, the murmur will generally be most intense over this vibration.
  • Murmurs that are only detected intermittently or are variable should be so indicated.
  • The radiation of the murmur should be indicated.[TOP]

Table 1. Grading of heart murmurs

Grade I

a very soft murmur only detected after very careful auscultation

Grade 2

a soft murmur that is readily evident

Grade 3

a moderately intense murmur not associated with a palpable precordial thrill (vibration)

Grade 4

loud murmur; a palpable precordial thrill is not present or is intermittent

Grade 5

a loud cardiac murmur associated with a palpable precordial thrill; the murmur is not audible when the stethoscope is lifted from the thoracic wall

Grade 6

a loud cardiac murmur associated with a palpable precordial thrill and audible even when the stethoscope is lifted from the thoracic wall
  • Other descriptive terms may be indicated at the discretion of the examiner; these include such timing descriptors as: proto(early)-systolic, ejection or crescendo- decrescendo, holo-systolic or pan-systolic, decrescendo, and tele(late)-systolic and descriptions of subjective characteristics such as: musical, vibratory, harsh, and machinery. [TOP]

Table 2. Congenital Cardiac Disease Statistics - 445 Samoyeds [Dec. 2009]

% Normal

% Equivocal

% Affected





Effects of heart rate, heart rhythm, and exercise
  • Some heart murmurs become evident or louder with changes in autonomic activity, heart rate, or cardiac cycle length such changes may be induced by exercise or other stresses. The importance of evaluating heart murmurs after exercise is currently unresolved. It appears that some dogs with congenital subaortic stenosis or with dynamic outflow tract obstruction may have murmurs that only become evident with increased sympathetic activity or after prolonged cardiac filling periods during marked sinus arrhythmia. It also should be noted that some normal, innocent heart murmurs may increase in intensity after exercise. Furthermore, panting artifact may be a problem after exercise.
  • It is most likely that examining dogs after exercise will result in increased sensitivity to diagnosis of soft murmurs but probably decreased specificity as well. Auscultation of the heart following exercise is at the discretion of the examining veterinarian.
  • At this time the OFA does not require a post exercise examination in the assessment of heart murmurs in dogs; however, this practice may be modified should definitive information become available. [TOP]
Definitive diagnosis of CHD usually involves one or more of the following methods:
  1. Echocardiography with Doppler studies
  2. Cardiac catheterization with angiocardiography
  3. Post-mortem examination of the heart (necropsy).

Other methods of cardiac evaluation- including electrocardiography and thoracic radiography, are useful in evaluating individuals with CHD, but are not sufficiently sensitive nor specific to reliably identify or exclude the presence of CHD.

  1. The noninvasive method of echocardiography with Doppler is the preferred method for establishing a definitive diagnosis in dogs when CHD is suspected from the clinical examination. Echocardiography is an inappropriate screening tool for the identification of congenital heart disease and should be performed only when the results of clinical examination suggest a definite or potential cardiovascular abnormality.
  2. Two-dimensional echocardiography provides an anatomic image of the heart and blood vessels. While moderate to severe cardiovascular malformations can generally be recognized by two-dimensional echocardiography, mild defects (which are often of great concern to breeders of dogs) may not be identifiable by this method alone.
  3. Doppler studies, including pulsed wave and continuous wave spectral Doppler, and two-dimensional color Doppler demonstrate the direction and velocity of blood flow in the heart and blood vessels. Abnormal patterns of blood flow are best recognized by Doppler studies. Results of Doppler studies can be combined with those of the two-dimensional echocardiogram in assessing the severity of CHD. Color Doppler echocardiography is used to evaluate relatively large areas of blood flow and is beneficial in the overall assessment of the dog with suspected CHD. Turbulence maps employed in color Doppler imaging are useful for identifying high velocity or disturbed blood flow but are not sufficiently specific (or uniform among manufacturers) to quantify blood velocity. It is emphasized that quantitation of suspected blood flow abnormalities is essential and can only be accomplished with pulsed or continuous wave Doppler studies. Pulsed wave and continuous wave Doppler examinations provide a display of blood velocity spectra in a graphical format and are the methods of choice for assessing blood flow patterns and blood velocity in discrete anatomic areas.
  4. Cardiac catheterization is an invasive method for identification of CHD that is considered very reliable for the diagnosis of CHD. Cardiac catheterization should be performed by a cardiologist, usually requires general anesthesia, carries a small but definite procedural risk, and is generally more costly than noninvasive studies. While cardiac catheterization with angiocardiography is considered one of the standards for the diagnosis of CHD, this method has been supplanted by echocardiography with Doppler for routine evaluation of suspected CHD.
  5. Necropsy examination of the heart should be done in any breeding dog that dies or is euthanized. The hearts of puppies and dogs known to have cardiac murmurs should always be examined following the death of the animal. A postmortem examination of the heart is best done by a cardiologist or pathologist with experience in evaluating CHD. While it is obvious that necropsy cannot be used as a screening method, the information provided by this examination can be useful in guiding breeders and in establishing the modes of inheritance of CHD. [TOP]

Each of the methods of evaluation indicated above may be associated with false positive and false negative diagnoses. It must be recognized that some cases of CHD fall below the threshold of diagnosis. hi other cases, a definitive diagnosis may not be possible with currently available technology and knowledge. These limitations can be minimized by considering the following general guidelines:

  1. The results of the examinations described above are most reliable when performed by an experienced individual with advanced training and experience in cardiovascular diagnosis. Echocardiography with Doppler, cardiac catheterization, and postmortem examination of the heart for CHD requires advanced training in cardiovascular diagnostic methods and the pathology and pathophysiology of CHD.
  2. Examinations performed in mature dogs are most likely to be definitive. This is especially true when considering mild congenital heart defects. Innocent heart murmurs are less common in mature animals than in puppies and are less likely to be a source of confusion. Furthermore, the murmurs associated with some mild congenital malformations become more obvious after a dog has reached maturity. While it is quite reasonable to perform preliminary evaluations and provide provisional certification to puppies and young dogs between 8 weeks and 1 year of age, final certification, prior to breeding, should be obtained in mature dogs at 12 months of age or older.
  3. Examination conditions must be appropriate for recognition of subtle cardiac malformations. The identification of soft cardiac murmurs is impeded by extraneous noise or by poorly restrained, anxious, or panting dogs.
  4. A standardized cardiac clinical examination must be performed according to a predetermined and clearly communicated protocol. Physical examination and cardiac auscultation should be used as the initial method of cardiac evaluation. If the clinical examination is normal, no further diagnostic studies are recommended. If the clinical examination is abnormal, a tentative diagnosis may be made, but the definitive diagnosis generally requires other diagnostic studies (as indicated above).
  5. Examiners who perform echocardiography with Doppler must use appropriate ultrasound equipment, transducers, and techniques. Such individuals should have advanced training in noninvasive cardiac diagnosis and should follow diagnostic standards established by their hospital and by the veterinary scientific community, including standards published by the American College of Veterinary Internal Medicine, specialty of Cardiology (J Vet Internal Med 1993; 7:247-252). [TOP]

Examination of dogs for CHD is aimed at the identification and classification of phenotypic abnormalities. Heritable aspects of CHD cannot be addressed unless suitable genetic studies have been conducted.


For more information visit OFA's official website.

Contact OFA directly for specific information on the OFA registries:
Orthopedic Foundation For Animals
2300 E. Nifong Blvd.
Columbia, MO 65201-3856
phone (573) 442-0418
fax (573) 875-5073

Dr. R.A. Weitkamp ~ President
Greg Keller, DVM, MS ~ Executive Director



I'd like to thank the Orthopedic Foundation For Animals for their permission to reproduce this information from the brochure on the Congenital Cardiac Registry. [TOP]

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Last updated: Saturday, February 06, 2010

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