Congenital deafness in dogs – BAER testing and daily life

Overview

Hearing impairment can remain hidden

Deafness means an inability to perceive sound. Hearing impairment can also be classified by when it starts and how it arises. Congenital and hereditary do not mean exactly the same thing, because damage before birth can also cause deafness. In some breeds, hereditary hearing impairment may not begin until later life.

Damage involving the sensory cells of the inner ear is called sensorineural hearing loss. This differs from conductive hearing loss, in which sound cannot properly reach the inner ear, for example because of a blockage. Damaged inner ear sensory cells do not regain function.

A dog deaf in only one ear can hear through the other and may respond to ordinary calls. A dog deaf in both ears relies more heavily on sight and perception of vibration. A deaf dog can live a long, fulfilling life when daily guidance and safety meet their needs.

Causes

Pigment cells help the inner ear develop

Genes associated with white spotting and merle colouring can predispose dogs to inner ear deafness. This involves more than coat colour: pigment-producing melanocytes are also needed in the developing ear. These cells maintain a vascular network important for inner ear fluid balance. Their absence can cause inner ear structures to degenerate and hearing to be permanently damaged.

The usual pigment-associated damage develops around 1–3 weeks after birth. A puppy can therefore lose hearing very early even if the defect was not complete at the moment of birth. Colour-associated inheritance does not usually follow a simple single-gene pattern. Hearing parents can produce deaf puppies.

Not every form is linked to white colouring

Hereditary sensory cell degeneration unrelated to pigment patterns also occurs. It is usually bilateral and starts with sensory cell loss at 1–3 weeks of age. Some forms can involve balance signs, for example in Dobermanns. Viral or toxic damage before birth is a separate possible cause of congenital hearing impairment.

Risk factors

Congenital deafness has been described in more than 100 dog breeds. Recognised risk groups include Dalmatians, Bull Terriers, Australian Cattle Dogs, English Setters and Parson Russell Terriers. It also occurs in many other breeds. White colouring and blue eyes are associated with pigment-related predisposition. Each dog's ear function is nevertheless established through a hearing test.

In Dalmatian puppy reports from northern Europe covering 2012–2021, around 14% could hear in only one ear. Around 4% were completely deaf. These figures include puppies identified as deaf by breeders, rather than only BAER-tested dogs. In Bull Terrier BAER results from northern Europe for 2015–2024, 8% could hear in only one ear. These are breed-specific monitoring data, rather than a combined risk figure for all dogs.

The 2012–2021 Dalmatian monitoring covered 1,437 puppies. Of these, 1,186 could hear in both ears. There were 196 hearing in only one ear. A total of 55 were completely deaf. Not every litter's report had been submitted to the breed organisation, so monitoring did not cover every litter.

In the Bull Terrier data, 78 dogs had their hearing tested during 2017–2024. Of these, 4 were deaf in one ear. Owners' survey answers and official BAER results are separate data and are not combined into a single prevalence figure.

Typical symptoms

Deafness is generally easier to recognise from around 3–4 weeks of age, particularly when observing a puppy separately from the others. Possible signs at home include:

• A puppy does not turn towards their name or a familiar sound signal.
• A sleeping dog does not wake to a sound that does not also move the supporting surface.
• A dog seems slow to learn spoken commands.
• Locating the direction of a sound is difficult even though the dog notices it.
• A dog turns more readily towards their hearing side.
• Barking increases or vocalisation becomes unusual.
• A dog startles more readily at touch or a person appearing nearby.

A dog deaf in one ear may still move both ear flaps on hearing a sound. Following the other puppies' behaviour can conceal a hearing impairment.

Complications and consequences

Unheard dangers

A deaf dog cannot hear approaching traffic or a car horn. Sudden startling can increase the risk of defensive biting. Deafness in one ear can also make sound localisation difficult and cause welfare problems.

Deafness itself does not mean pain or ongoing discomfort. Some developmental abnormalities associated with merle colouring can also affect the eyes. White, poorly pigmented skin may additionally sunburn more readily. These associated issues are distinguished from the absence of hearing itself.

Outlook for hearing loss

Congenital deafness caused by loss of inner ear sensory cells is permanent. Conductive hearing loss, however, may resolve if a blockage or inflammation preventing sound transmission is treated. Investigations establish this distinction; a deaf puppy is not automatically assumed to have an ear infection.

Diagnosis at the vet

Home observations do not assess both ears

Your vet asks how the puppy responds to sounds and when abnormal hearing was noticed. Hearing can initially be assessed using a sound outside the dog's field of vision. A visual cue or vibration through the supporting surface can nevertheless make a deaf dog respond. Behavioural testing does not reliably identify deafness in one ear. Stress or repetition of the same stimulus can also alter a dog's response.

The ear canals and visible eardrums are examined before BAER testing. Ear imaging and neurological examination investigate other causes of hearing impairment where necessary. A neurological examination assesses alertness, movement and cranial nerve function, among other things.

BAER records the auditory evoked response

During a BAER examination, short clicking sounds are delivered through earphones to each ear separately. Small electrodes beneath the skin record electrical responses from the auditory nerve and brainstem. The result is displayed as a trace used to classify the dog's response. A dog may be sedated so that movement does not interfere with recording.

In one official screening scheme, testing uses a sound level of 70–95 dB nHL. Background noise is reduced by averaging at least 1,000 stimulus repetitions. A masking sound delivered to the other ear prevents confusion with that ear's response. More detailed hearing threshold measurement can complement ordinary hearing–deaf screening.

Inner ear sensory cell function can also be investigated through otoacoustic emissions: very quiet sounds produced by the ear in response to a sound stimulus.

An example of official screening rules

Under one official BAER scheme, an identified puppy can be tested from at least 35 days of age. A vet approved by the scheme issues the report. Each ear is classified as hearing, deaf or inconclusive. An inconclusive result is unofficial. Retesting is then recommended after around 4 weeks. The dog's overall official result follows the worse ear.

Under that scheme, a result obtained before 3 months of age can be changed through retesting until the dog reaches 6 months. If the first test takes place at 3 months or older, only a panel can change the official result. The examiner records the report in the scheme's database. The owner also receives the dog's auditory response traces.

An adult dog can also have a hearing test if no early test record is available.

Treatment

Support centres on effective communication

Your vet assesses the type of hearing impairment and whether another ear disease needs treatment. No drug treatment restores hearing in hereditary sensory cell deafness. If investigations find an ear canal blockage, treating it may restore hearing impaired through poor sound conduction. Bacterial middle or inner ear infection may require an antibiotic.

A deaf puppy can be trained using hand signals and consistent body language. First, the dog's attention is directed towards the person so that they can see the signal. A clear daily routine helps with learning mealtimes and house training. A trainer experienced with deaf dogs can help identify suitable ways to communicate.

A hearing canine companion can provide behavioural cues that a deaf dog follows. This does not replace learning visual communication with people. The benefits of hearing aids in animals have remained limited. The practical aim of care is safe, understandable daily life even though inner ear hearing loss remains.

Prevention

BAER screening and informed breeding choices help reduce hereditary deafness. Some breeding guidelines recommend that dogs deaf in both ears or hearing in only one ear should not be bred from. A dog deaf in one ear can also pass an increased risk of deafness to offspring. Parents tested as hearing reduce the risk but do not eliminate the possibility of a deaf puppy.

Genetic testing is available for only some forms of deafness, such as certain hereditary hearing disorders in Rottweilers and Dobermanns. BAER measures an auditory response and is therefore not a general carrier test for every deafness gene. Testing a litter before puppies move to new homes also helps identify hearing impairments that are not outwardly apparent.

Important for dog owners

Ask for the puppy's BAER result for each ear and the auditory response traces if the breed or litter's background warrants it. Keep your dog on a lead near traffic. Off-lead exercise takes place in a safely enclosed area. An ordinary spoken recall will not stop a dog deaf in both ears.

Approach your dog without startling them through unexpected touch. Some dogs detect floor vibrations, but not all respond in the same way. Children are also taught to handle a deaf dog calmly and respect rest periods.

Do not automatically interpret ignoring spoken commands as disobedience. Agree the same hand signals and ways of gaining attention across the family. Record new ear pain, a balance change or deterioration in the previously hearing ear separately. Another ear disease can arise alongside congenital hearing impairment.

Frequently asked questions

How can you tell whether a puppy hears in both ears?

A response to sound at home does not confirm hearing in both ears. A puppy deaf in one ear can respond through the hearing ear and follow the other puppies' behaviour. BAER testing assesses each ear separately and also identifies deafness in one ear.

Can congenital deafness resolve?

Hearing loss caused by destruction of inner ear sensory cells is permanent. This differs from hearing impairment caused by an ear canal blockage or another obstruction to sound conduction, which may resolve with treatment. A deaf dog can nevertheless learn hand signals and enjoy a fulfilling daily life.

Are all white or blue-eyed dogs deaf?

White colouring and blue eyes are associated with the risk of some hereditary hearing disorders, but appearance does not establish an individual ear's function. Dogs also develop other hereditary hearing impairments unrelated to pigment patterns. A hearing test investigates the suspicion.

When can a puppy have a BAER test?

Under one official screening scheme, an identified puppy can be tested from at least 35 days of age. If the result is inconclusive, retesting is recommended after around 4 weeks. An inconclusive result is unofficial under that scheme. Hearing in each ear is classified separately.

Can a dog deaf in one ear be used for breeding?

Some breeding guidelines recommend excluding dogs deaf in one ear from breeding as well. Apparently good everyday hearing does not remove the risk of hereditary deafness in offspring. Deaf puppies can also be born to parents both tested as hearing in both ears.