Holter testing

It was time at Braebrook for the annual holter monitor testing. We holter test our dogs for DCM. If you don't know anything about DCM or holter testing I think this explains it well;

What is dilated cardiomyopathy (DCM)? Dilated cardiomyopathy is an acquired disease that is characterized by a markedly enlarged and weakened heart muscle. In the Doberman it affects mainly the left ventricle and left atrium. It results in electrical abnormalities (irregular or abnormal or premature beats). These electrical abnormalities may result in sudden death (described below) as the very first clue of a problem in your dog. Most dogs experience symptoms of pulmonary edema with respiratory distress. DCM is observed in dogs, cats and humans, as well as a number of other species.

Dilated cardiomyopathy is always rapidly fatal in Dobermans.

What is a Holter monitor? A Holter monitor or recording (also called ambulatory electrocardiography) is a recorder (usually a cassette recorder although some now hold and use a small computer chip) that is placed or attached to the chest of the dog with bandage material. It enables one to collect all the heart beats a dog (or person) will produce in 24 hours. Also importantly this is done in the environment of the dog, that is in the dog’s household and while the dog is running at the park, etc. Hence we are able to relate any abnormalities to the activity of the dog should there be a relationship.

What does a Holter examination tell us? A Holter exam is used to tell us:

• If an apparently normal Doberman has reached the second stage of DCM (also called occult DCM). If this is the case it means the dog should be started on medication to delay the progression to the third and final stage of DCM.
• That the dog is at risk for developing sudden death.

As of today (May 2000), the Holter exam provides us with 24 hours of ECG (this will collect about 130,000 heart beats). This test will allow us to determine the presence and number and complexity of abnormal heart beats (called PVCs) (potentially a very strong marker for dogs in stage two of DCM and destined to die of DCM if the frequency and or complexity of PVCs is substantial). In addition, this test will allow us to measure Heart Rate Variability (a measure of the balance of adrenalines in the body and a risk marker for people and presumably dogs at risk for sudden death).

Most Holter exams are analyzed by human laboratories. As a result the data usually carries many errors, due to the differences between dogs and people. Overall, it should be able to tell you if PVCs were present or not but an accurate count is usually not available.

I recommend you have your Holter exam analyzed by a veterinary institution. At the University of Guelph we employ a rigorous quality control program on all analyses such that each 24-hour exam requires from 2 to 5 hours of work to correct/review the automated analysis by the analyzer to ensure an accurate report.

What are PVCs or VPCs? PVCs refer to premature ventricular contractions. VPCs refer to ventricular premature contractions. These are identical; two short forms for the same thing. They can only be identified on the ECG whether it is a short study (up to 3 minutes) or a 24-hour study (Holter exam). PVCs occur in the second and third stages of DCM.

PVCs are of most interest to us in symptom free Dobermans because their presence serves as a marker for Dobermans in the second stage of DCM (occult DCM) if they are sufficiently frequent. We used to believe that all symptom free Dobermans with as few as 1 VPC on a 3 to 6-minute ECG identified dogs in stage two of DCM. However, we have observed a number of dogs with very few VPCs on a routine ECG that over many years never went onto develop DCM. Thus, dogs with very few VPCs may or may not be destined to acquire DCM.

If you'd like to read more you can follow this link where the above passages came from.

 I generally start holter testing at approx 3 years of age, and even that is on the early side. I think better safe than sorry however and once you have a holter, which can be a considerable expense, or you can rent or borrow one, the test itself is only $30 per dog.

My testing this year included five dogs. Here is Ch Modadobe Sunset Dreaming "Phoebe" getting kisses from Marshall early in the day.

And finally crashed out on the couch at the end of the day. Each dog is tested for 24hrs. Phoebe's results came back showing 0 PVCs which is exactly what I want to see.

Here's Ch Esquire's Celtic Woman "Enya" sulking when the monitor first goes on. She wasn't sure why she had to wear a vest, but got over it about 2.5 seconds later. Her results came back showing 0 PVCs as well. Both Phoebe and Enya are four years of age.

Next was Esquire's Haiku "Hadley". Hadley is only turning two years old this month so is pretty young to be holter testing but because I was doing everyone else I decided to do her too. She came back with 0 PVCs.

Next was Holmrun's Glitterbug Bruda CD CGN "Lexi". Lexi will be nine years old in April and she too came back with  0 PVCs which I was thrilled about. Often times as they get older they will have a few or even a lot as DCM usually strikes in the older years so a nine year old dog with none makes me very happy.

Last but not least was Ch Holmrun's Bo Jolais Braebrook CGN "London" who is turning 8 this month. I didn't get a picture of her (bad owner) but she came back with 8 single PVCs which is still very much in the "safe" zone, and is quite good in a dog of her age.

If you have any interest in purchasing a holter for yourself you can contact Alba Medical who sells them and who run some great monthly specials.

Or if you have just one or two dogs and would like to rent a holter many local Doberman clubs have them available. If you are in BC like me you can contact the BC Doberman Pinscher Club.