Veterinary Brainstem Auditory Evoked Response (BAER) Evaluation System
Suzanne Nevada, SilverAurora Kennels, Wasilla, Alaska, with her Australian Cattle Dog, Teddy
The BAERCOM concept
BAER testing is the standard method used to check for hearing defects in dogs. Many breeds of dogs are susceptible to genetic causes of deafness; BAER testing is used to exclude deaf dogs from the breeding pool. Canine BAER testing is generally performed at about 6-8 weeks of age, and is always recommended for susceptible breeds before first sale or breeding.
Until recently there were very few locations available for BAER testing, typically just the few universities with veterinary schools such as the University of California, Davis and University of Colorado. This made it inconvenient, as well as expensive, for breeders of susceptible breeds to have puppies tested.
A few years ago, the only equipment available for canine BAER testing was that developed for human use. Human-approved equipment meets very high standards and includes capabilities not required for screening puppies for deafness. Human-approved equipment costs $10,000 or more, which is prohibitive for the general veterinary practitioner.
UFI has developed a low cost device, the BAERCOM™, that is aimed at inexpensive puppy screening. The BAERCOM includes only the minimum functionality required to test for hearing ability and eliminates functions that are unnecessary for this purpose. It does not have the extensive capabilities of the more expensive audiological testing machines, nor are we portraying the BAERCOM as a direct replacement for these devices or for the centers that operate them. The BAERCOM is a portable system at a reasonable cost.
Definitive screening tests are no longer the province of just the large veterinary centers. They can now be performed locally using the reliable, portable cost effective BAERCOM system.
The BAERCOM instrument
The BAERCOM is a portable, stand-alone, 9V-battery-powered BAER hearing evaluation device for veterinary research and testing on dogs, cats, and other small- and medium-size animals.
The BAERCOM synchronizes click generation and EEG data collection to sample 11 milliseconds of EEG data, starting with the click onset. The resulting summed BAER response waveform is rapidly compiled and displayed on the graphics LCD.
The BAERCOM can be operated as a "stand alone" BAER evaluation tool, with the resulting BAER response clearly displayed on the graphics LCD. Up to 23 BAER response plots can be saved in memory inside the BAERCOM. Any of these recorded BAER plots can be displayed on the built-in LCD. They can also be downloaded to a PC when convenient.
PC software for the BAERCOM
Each BAERCOM comes with PC software that can download the BAER data from the BAERCOM and save the data to your computer. The BAER response for both ears is posted on a simple, easy to use form (shown above) that can be printed. BAER plots can also be copied to the PC clipboard for use by other applications.
The BAER traces shown above were collected with the BAERCOM from a lightly sedated, one-year-old male Dalmatian with unilateral hearing loss in the left ear. The collection of this BAER data for both ears took less than 5 minutes. Most pups, including the one in the picture at the top of the page, do not require sedation at all.
These lessons are adapted from the BAERCOM instruction manual. If you do not yet have a BAERCOM, these lessons can show how easy the BAERCOM is to use. If you do have a BAERCOM, you can use these lessons to supplement the information in the manual, or in case it is lost.
- Stimulus method: one piezo-electric earphone (supplied) that fits into patient's ear (bone conduction or inductive earphones do not work)
- Stimulus click amplitude: 6 settings between 40 and 80 dB
- Stimulus click frequency: fixed, < 1 mS duration.
- Number of EEG channels: one
- EEG input: Two active needle electrodes plus a reference on the subject are connected via input leads with alligator clip terminations. Stainless steel hypodermic needles work well for the electrodes. Medical supply houses can provide a variety of purpose-designed needle electrodes as well.
- EEG data collection period (one pass): 11 milliseconds
- EEG pass repitition rate: every 25 milliseconds
- Collection process: The BAERCOM collects 100 passes of EEG response data, then averages the data with any previous data. The BAERCOM plots the composite average on the LCD and then collects the next set of 100 passes. Collection can be stopped at any time.
- Data storage: Up to 23 final BAER data sets can be saved in non-volatile memory inside the BAERCOM. Saved BAER data can be reviewed on the built-in LCD or downloaded to a PC computer with the BAERCOM software.
- Saved BAER data file format: two sets of BAER data encoded as decimal ASCII along with various headers and text information. This file can be opened with most word processing software.
- PC operating system: Windows 98 and later (not yet available for Mac or Linux)
- BAERCOM-to-PC interface: isolated USB cable
- Power supply: standard rectangular 9V alkaline battery
- Estimated battery life: approximately 24 Hours "on" time
- Instrument size: rugged plastic case is approximately 1.5" x 5" x 7" (40mm x 130mm x 180mm)
- Instrument weight: approximately 16 ounces (450 grams)
For several years, UFI paid a local veterinarian to perform a final system check on each newly assembled BAERCOM. A puppy with hearing known to be normal served as the BAERCOM test subject. Then about four years ago, UFI Engineering devised a compact -- 1.5" x 5" x 7" (40mm x 130mm x 180mm) -- electronic stand-in for the puppy, resulting in faster and less costly quality control. We've just made this BAERCOM Simulator even more user-friendly and reliable, and are now happy to offer it as a standard product to BAERCOM owners worldwide.
How does it work? Just insert your BAERCOM earpiece into the panel-mounted microphone on the simulator to create an acoustic link. Then clip the BAERCOM input assembly to the simulator's snap terminals rather than to the electrodes you'd normally use with a live subject. Power up both units; each burst of BAERCOM stimulus clicks triggers a simulated waveform like the one made by the auditory nerve in a real animal with normal hearing.
With the BAERCOM Simulator, Baercom users can now
- check to be sure a BAERCOM is operating normally before use with a live animal
- quickly and easily compare a stored, normal brainstem auditory evoked response with a problematic one from a particular live subject
If you are an individual interested in purchasing the BAERCOM™, please check with your local veterinarian to see if there are any legal issues involved. In many locations, you can probably do almost anything you wish with your own animals, including testing them with the BAERCOM. However, if you charge a fee for doing anything with another's animals, you are probably required by local law to be a licensed veterinarian, a point on which we fully agree. UFI urges complete and full compliance with any local laws that relate to BAER testing in your area.