The increasing awareness of hearing loss in pets

Although acquired deafness usually occurs later in life, any animal is susceptible to being affected by hearing loss. Experts admit that there are no real behavioral cues and it often goes undetected. Early detection and correct diagnosis of hearing issues can improve a pet’s quality of life by ensuring they receive the right treatment.

Behavioral assessment

Diagnosis of hearing loss in pets typically falls into one of the following categories: congenital, hereditary, acquired sensorineural and acquired conductive deafness. It is generally not possible to distinguish between hereditary and acquired deafness without breeding trials. However, according to research, the most common form of deafness in young dogs and cats is the so-called congenital hereditary sensorineural deafness (CHSD).

Currently, there are no DNA tests to detect this. Instead, an initial and very basic diagnosis is reached by exposing pets to familiar sounds and increasing the volume. The reality is that this type of behavioral assessment of an animal’s hearing, either at a clinic or in the home, is of limited reliability.

Current solution has a high price tag

Electrodiagnostic tests are necessary for an objective assessment, but these have a high price tag. The brainstem auditory evoked response (BAER) test is currently the only accepted method for diagnosing deafness in pets. First used in veterinary research in
the 1970s and in clinical applications in the early 1980s, it detects electrical activity in the cochlea and auditory pathways in the animal’s brain.

Depending on the options, BAER machines cost a minimum of $15,000-$25,000 (€14,000-€23,500), which puts them out of the price range of most veterinary practices. “Engineering could undoubtedly produce smaller and lower-cost devices, but it probably won’t go far in that direction because of cost/benefit issues,” admits Dr. George Strain, Professor of Neuroscience at Louisiana State
University and an expert in the field of animal deafness.

Toward easier detection

Dr. Strain is keen for new and less costly tests to be developed that could make it easier for vets to diagnose pets with hearing problems in their clinics. 

Therefore, he recently completed a study on a cheaper and more readily available tool, similar to a device that tests human babies’ hearing based on so-called distortion product otoacoustic emissions (DPOAE). According to Dr. Strain, there is some scientific evidence suggesting that this technique could be applied to pets too. “However, although the preliminary studies demonstrate a successful outcome in simple cases with the new procedure, extensive testing will be required to clarify this,” he admits.

For now, animals with equivocal or abnormal DPOAE results will still need to be referred for BAER testing, he explains: “Clinically, testing assesses whether hearing is present or absent. We don’t quantify hearing loss when it is partial, and we are unable to test different frequencies. High and then middle frequencies are the ones lost first with acquired hearing loss, so the BAER test will not become obsolete anytime soon.”

Hearing protection devices

In the context of well-being, Dr. Strain is also a strong advocate of effective hearing protection devices for animals. As an example, he mentions that the US Army has issued a call for proposals to develop hearing protection devices for military dogs. The devices must be tolerated, permit passage of frequencies for speech and radio command transmission, and also protect the animals against loud noises, especially at high and low frequencies.

“Such devices would also be very useful for hunting dogs, who often lose hearing because gunfire near their head leads to progressive hearing loss,” he admits in an interview with PETS International. With owners increasingly conscious of the well-being of their furry friends, this could be an interesting future development for the pet market too.