Contact: Aga Haupt
A team of Mississippi State veterinary faculty members, clinicians and students is working to demonstrate that a hunting dog's frequent exposure to gunshots can progressively damage the animal's hearing.
A first, the university study of noise-induced deafness in dogs is being supported by the College of Veterinary Medicine's Office of Research and the Denver, Colo.-based American Animal Hospital Association Foundation.
"A partially deaf dog is not as effective as either a hunter or as a pet," said Dr. Andrew Mackin, holder of the college's Hugh Ward Chair in Veterinary Medicine and an associate professor in small animal internal medicine.
To make the investigation as scientifically controlled as possible, Mackin said the team only is testing Labrador retrievers. In addition to being quite common in Mississippi, the breed habitually sits near the hunter and, therefore, close to his or her shotgun.
Mackin said the test subjects are middle-aged animals 4-10 years old. "We wanted dogs that are old enough to have hunted at least a couple of seasons, yet not old enough to be going deaf out of old age," he explained.
Because swimming can cause ear infections leading to progressive hearing loss, the team screened candidates to rule out evidence of past or current infections, Mackin said.
During the testing, Mackin and his team sedate the dogs and attach scalp electrodes and a tiny probe in the dog's ear canal. The probe sends a repeated clicking noise and the researchers record the electrical pattern in the dog's brain to see how well the dog can hear. The test is repeated in both ears and the results are compared. The hearing test is a painless, standard way of testing for deafness in animals.
"We routinely perform this kind of hearing test for pet owners," Mackin said.
While a healthy Lab begins to hear sounds at about 10 or 15 decibels--much like a healthy human--Mackin said one test animal that has been heavily exposed to gunshots didn't respond until 60 decibels, which is quite loud.
The research group also includes Dr. David Jennings, a neurologist, and Dr. Amy Janda, a small animal intern, as well as two veterinary students. Janda said the sound at 60 decibels is comparable to half the noise of a jet engine.
The team's original research proposal called for testing a total of 40 dogs, 20 hunters and 20 non-hunters.
"The difficult thing in Mississippi is to find a Lab retriever that never has been hunting," Mackin said. As a result, team members decided to forgo a search for 40 animals.
"We are very excited about our preliminary data," he said. "Practically all of the hunting dogs have some hearing loss and practically all of the non-hunting dogs have great hearing."
The difference in hearing ability between the two test groups "is extreme," he added.
Ultimately, results of the study could have great consequences for hunters.
"Perhaps in the future we will recommend the same precautions for hunting dogs as for hunters, including earplugs," Mackin said.