Heart Testing

Auscultation - examining with a stethoscope.


This is an essential part of examining the animals heart and circulation.
Any heart murmurs are identified, timed, localized and graded (0-6 no half measures!) A careful note of the heart rhythm is also made. Heart murmurs are a feature of most congenital heart defects CHD and mitral valve disease. Some common forms of congenital heart disease include aortic Stenosis (AS), patent ductus arteriousus (PDA), and pulmonic Stenosis (PS). Abnormal heart rhythms
may occur without murmurs in dilated Cardiomyopathy (DCM).

It may be difficult for a cardiologist to detect a quiet murmur in a noisy room or in a dog which fidgets. Some murmurs can increase or alter at different heart rates like after exercise or excitement. If a significant murmur is detected the cardiologist may advise the condition be further investigated. Although all veterinary surgeons will listen to your dogs heart, breed club schemes use veterinary cardiologists, vets who have received training, and have passed post-graduate exams and is able to grade heart murmurs in a way which is
consistent with other cardiologists.

Electrocardiograph (ECG)

This is always indicated when or if an abnormal heart rhythm is detected. It is most often used to screen for DCM (dilated Cardiomyopathy) though it is less sensitive at detecting CDH or MVD.

Echocardiogram (with doppler)

Two dimensional echocardiography allows visualization of a 'slice' through the heart in real time. It allows measurements to be taken and compared with normal values for the breed or size of the dog. Severe CHD, MVD, or DCM are usually evident using these techniques. How ever, Doppler is also required to confirm the diagnosis of the specific type of CHD, and to identify mildly affected animals. It will confirm whether or not there is a significant cause of the heart murmur, or whether it is 'innocent'. In some cases, it is difficult to be certain whether the dog has mild disease or an innocent murmur. Doppler will allow the cardiologist to give a prognosis about the severity of any disease. Veterinary cardiologists normally carry our Doppler examinations, as this is a very skilled technique which requires considerable expertise and experience.

 

UNDERSTANDING HEART SCORING

 

You will read and hear much about heart testing Boxers, the heart testing scheme has been in use for about thirteen years now, we have always tested our
breeding stock and adhered to breed council guidelines. However there can be confusion regarding the testing of Boxers so, to clarify things a little:

The current heart scoring system DOES NOT make allowances for half marks in heart scoring. You will not see a dog or bitch graded on the heart list as a 1.5, or 0.5, they are either 0,1, 2,etc. For example, if there is a shred of doubt when scoring a dog, then a one MUST be graded as a two, unless the animal is dopplered (a type of ultra sound scan carried out by a veterinary cardiologist) in this instance a more accurate figure can be given. Simplistically, the specific recommendations for breeding are: All breeding stock should be screened by designated cardiologist. Those animals which are free of heart murmurs (grade 0) may be considered free of aortic and pulmonic Stenosis, and are suitable for breeding purposes. Those animals which have a minor murmur (grade 1) may be accepted as normal and are suitable for breeding purposes. Bitches who are scored over a 1, therefore as a grade two, are
considered acceptable as brood bitches providing they are mated to a clear dog,
either a 0 or a 1. Dogs with murmurs of a grade two or louder, should not be used as stud dogs, except in exceptional circumstances, then only to a clear bitch.

 

One of the reasons for this is because a bitch is only able to have a limited number of puppies in her lifetime, where a dog is potentially able to sire thousands of puppies. Therefore this is self-limiting. Genetics is not an exact science (if only it were that simple), we all know of a 0 being mated to a 0, yet some of the pups may be graded as 2’s, but, the heart testing scheme is beginning to reduce the problems of heart disease among our dogs, and by following breed guidelines we as breeders are now beginning to see the rewards of heart testing our breeding stock before they are bred from.

Ref: Boxer Breed Council.

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