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Welcome to the world of Canine Holter, and congratulations for taking the first step toward a more positive future for our breed. Of any device currently available, most Veterinary Cardiologists agree that the Holter monitor provides the earliest detection of occult, or hidden, DCM (Dilated Cardiomyopathy) in dogs. Holtering your dog is a painless, simple, and easy to hook-up. It’s a cost effective way to test your dog for heart disease.
With equipment that’s readily available for purchase, anyone can Holter his or her dog. From pre-breeding and pre-surgical needs to annual adult and senior wellness care, Holter monitoring offers invaluable information regarding possible underlying heart disease. That information is power. The power that protects future generations by excluding affected individuals through our breeding decisions. The power that insures safe pregnancies, which increase the work load of the heart by at least two fold during the last trimester. The power that increases life expectancy through medication. The Holter monitor is changing our future.
What is a Holter Monitor?
The Holter monitor, named after its creator Dr. Norman Holter MD, records 24 hours of continuous heart rhythm (EKG or ECG) and heart rate (HR), while the dog goes about its normal daily activity in a home environment. The Holter is found to be a far superior test when compared to the 5-minute EKG, simply because of its 24-hour recording time.
The report generated from Holter data details the number of VPCs (Ventricular Premature Contractions), sometimes called PVCs (Premature Ventricular Contractions), present during the 24-hour period. Occult DCM is defined as 50 or more VPCs in 24 hours. Ideally, we are looking for a VPC score of ZERO or very close to zero. When needed, results can be reviewed by a Veterinary Cardiologist who may recommend further testing, or possible medications, to your Veterinarian.
With recent studies suggesting that up to 50% of all adult Dobermans will develop heart disease at some point in time; the need for personal Holter monitors is continuing to increase. All Dobermans, whether contributing toward the breed via the conformation ring, the performance venue, the whelping box, or the home as companions, can benefit from the serial use of a Holter monitor. Many of our DPCA Chapter clubs have purchased equipment to allow their members access to a Holter monitor whenever needed.
First Step: Cassette vs. Digital
Funding a Holter monitor can be easier than you might think. We can decide to purchase a Holter recorder as an individual, part of a group of local owners/breeders, or as part of a club to help complete DPCA/AKC educational/health requirements. Once we have the funding in place, there are two types of units available for our consideration.
The first is the original cassette tape or analog Holter recorder (refurbished, $500.00), and the second, the modern digital Holter recorder (new, $1500.00). The analog unit records information on an audio cassette tape, which is mailed to Alba Medical for analysis. It’s about the size of a paperback book and weighs 15 ounces.
The digital unit records information on a small compact-flash memory card, which can be uploaded via your PC and high-speed internet connection to Alba. The flash card could also be mailed to Alba, analyzed, and then returned to the owner. The digital unit is about the size of a small cell phone and weighs only 3 ounces.
The primary advantages to the digital unit are their small size and speed/ease at which information can be delivered digitally to Alba Medical. The digital unit’s display screen also allows the user to detect hook-up connection issues prior to starting the study thus reducing the rate of hook-up failures. Regardless of chosen unit, accurate and fast (1-2 day) Alba Medical service can be expected once your information is received.
Understanding 5 and 7-Lead units
Once we have chosen the type of machine (cassette tape or digital), we need to look at the desired number of leads. The Holter unit is connected to the patient via color-coded lead wires. The lead wires are attached to the patient via disposable electrodes consisting of a gelled electrode and adhesive pad. Electrodes, sealed in foil pouches, should always be used fresh out of manufacture’s packaging to insure a moist electrode surface. Dispose of any unused electrodes once foil pouches are opened.
Both Holter recorders are available in either 5-lead or 7-lead hook-up configurations. Both 5 and 7-lead units offer 3-channel recording, meaning they are logging 3 separate ECG tracings at any one time as long as all electrodes are firmly attached to the patient. The extra wires of the 7-lead unit give the benefit of spares in the event of electrode detachment. With spares, no one electrode serves double duty (see table below).
5-Lead 7-Lead
Brown to Red = channel one White to Red = channel one
Black to Red = channel two Brown to Black = channel two
Black to White = channel three Blue to Orange = channel three
Green = Ground Green = ground
In the end, only one channel (one pair of electrodes conducting left to right) is needed for the Holter report. Typically a 5-lead machine is all that is needed to get the results we are looking for. Working with 5 versus 7 leads also cuts down on the amount of shaving, and number of electrodes to remove the next day.
Do we really need to shave the hair?
Shaving is recommended though not required to Holter your dog. Alba Medical has had success with clients Holtering the unshaved dog. It is better to Holter unshaved than not at all if missing hair deters testing in the first place. The biggest issue with not shaving is early electrode detachment due to primary contact with hair instead of the skin. The act of shaving also insures the best possible electrical contact and thus the fully desired recording time
The more active the patient, the better contact we will need with the skin to allow for a complete recording. With thick coats, removing the guard hairs with a number 10 blade may assist in better skin contact yet allow a less obvious shaved box on the dog. Dogs with a thinner coat may very well get away with no shaving at all. Areas that are shaved typically appear fully coated in about 30 days.
When Electrodes detach
Electrodes can and do come off, so understanding how they transmit information is helpful. Just because we have lead detachment does not mean the test is invalid. The leads communicate to each other thru the chest cavity according to the channels listed above. Remember, we only need one channel operational to produce the Holter report.
For example:
5-lead unit with black lead detached: channel one operational, continue recording and re-attach black lead if possible. The black lead serves double duty in channel two and three.
5-lead unit with black and white detached: channel one operational, continue recording and re-attach black/white leads if possible
5-lead unit with black and brown or red detached: no channels recording. One will need to re-attach all electrodes. Depending on time completed, may want to redo entire 24hrs.
7-lead unit with black, brown and red detached: channel three recording
7-lead unit with white and red detached: channels two and three recording
If you ever lose ALL the electrodes on one side of the dog, there will definitely not be any signal recorded during that time. Depending on how long the wires were disconnected, the test may need to be repeated.
Holter Vest
The form fitting Holter vest is designed to hold the Holter monitor in place during operation and protect the electrodes, wires, and unit from any possible damage. Vests are fully adjustable, comfortable to wear, machine washable for reuse and designed to help protect the Holter from even the most active of canine patients. No Holter monitor package is complete without the purchase of a vest.
The Holter vest makes hook-up and removal easy. If you don’t use a vest, you will need to cover the wires and monitor with vet wrap. If the dog chews the wires, they can be replaced for $30 (cassette) or $65 (digital). If the dog destroys the machine, this is not covered under warranty, and you will need to replace a $500 or $1500 machine.
Some general Holter Tips:
- A birthday month is a great time to Holter your dog! Celebrate each birthday with a Holter report
- Check electrodes for moist contact, dry electrodes do not transmit information.
- Open sealed electrodes and use immediately. Left-over pieces should NOT be saved for use at a later time. These electrodes will dry out and could be non-operational.
- If zeros reported on digital screen during setup, remove and replace electrodes
- Consider purchasing one set of backup leads for each unit in the event of sudden damage
- New batteries should be utilized for each Holter study.
- New cassette tape should be utilized for each Holter study.
- Hookup kits are needed for both types of units, keep them on hand and ready to go.
- Repair services available. No need to be without a functional Holter unit.
- If your current leads are found to be shorter that you would like, longer leads are now available for the digital unit. Contact Alba for more information.
Holter hook-up is as easy as 1-2-3.
Our next article will detail the process step by step.
Alba Medical will be hosting a Holter clinic during the week of the DPCA 2010 National. No appointment is needed. Sign up at the registration table during the show at your convenience. Equipment will be available onsite for rental or purchase with a report back via email in 48 hours. Stop by and see how the Holter monitor can help protect your future.
Have a heart… Holter
Please send any questions for future discussion to
Dawn Danner, CVT
Veterinary Division Alba Medical
Sunsetdobe@aol.com
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