My name is Wendy Wallner. I am a veterinarian in the Atlanta, GA area and am the acting chair of the American Boxer Club's Health and Research Committee. I have recently instituted a screening protocol for American Boxer Club members to follow in an effort to attempt to identify dogs that have:
1) Congenital heart disease, specifically Aortic or Subaortic Stenosis, and/or
before these animals are used in a breeding program.
The screening protocol is as follows:
1 year- auscultation by board certified veterinary cardiologist (If arrythmia is present - Holter; If murmur present - Echo)
Rationale: One year is the accepted time for clearance of Aortic/Sub-aortic Stenosis. This auscultation screening could be performed at the national specialty and at individual breed club's specialty shows for a nominal fee. Any dogs with murmurs would be referred to a cardiologist in their area for further workup.
2 years - Holter monitor, auscultation (Echo if murmur present)
Rationale: The 2 year check would occur before the animal was used for breeding and would be useful in picking up dogs with early arrythmias before they are bred. In some boxers, arrythmias have been detected as early as 6 months of age.
5 years- Holter monitor, auscultation (Echo if murmur present)
Rationale: By 5 years many animals would show signs of arrythmia if they were going to develop cardiomyopathy since the arrythmia often precedes clinical disease by several years.
While we realize that this system of screening is flawed in that some animals with late onset of cardiomyopathy will have been used for breeding prior to having detectable signs of disease, and that the Holter monitor may not be a good predictive indicator of CM, it will at the very least help create a database for a large number of "normal" and "abnormal" boxers so that we can establish breed and age related data for Holter monitoring and possibly for echocardiography. It will also identify those dogs affected with Aortic/Sub-aortic Stenosis before they enter the breeding pool.
Just as an aside to this, and a rather disturbing one at that, Dr. Mike O'Grady at the Veterinary College in Guelph has done a study on Dobes and Cardiomyopathy. In that study, he followed the dogs for several years. His findings were that any dog that had a single VPC on ECG or Holter went on to develop CM. We can hope that this does not hold true for boxers, but I wouldn't count on it.