What a BAER result can establish

When a veterinary electrodiagnostics report arrives stating that a puppy or adult dog hears normally in both ears, is deaf in one ear, or is bilaterally deaf, owners and breeders face an immediate question: what does this labeled result actually confirm, and what limits remain unaddressed? A brainstem auditory evoked response (BAER) test—also termed brainstem auditory evoked potential (BAEP) or auditory brainstem response (ABR)—is an objective electrophysiologic procedure that detects whether acoustic signals physically evoke neural responses along the early auditory pathway. It does not test behavioral comprehension, does not produce a human-style frequency audiogram, and does not provide a genetic certification.

In short, a canine BAER screening result establishes one precise physiological fact on one specific date: whether each ear generated repeatable electrical waveforms—Peaks I and V judged present at their appropriate latencies—in response to a calibrated click at the tester's protocol intensity. The Orthopedic Foundation for Animals (OFA) congenital-deafness protocol uses a signal equivalent to 70–105 dB nHL. Presence of those peaks means that ear produced a time-locked response to that click on that day. An essentially flat tracing, without peaks that can be mistaken for movement artifact, means that ear did not produce a screening response to that stimulus.

To interpret the document properly, readers must distinguish between what the test confirms and what it cannot determine:

• What a BAER result can establish: Per-ear laterality of a screening click response (bilateral hearing, unilateral deafness, or bilateral deafness) when Peaks I and V are judged present or absent; an objective tracing that does not depend on a clap, whistle, or other behavioral trial; and whether that labeled packet matches the registry named on the form (OFA or a separate Kennel Club programme), including that programme's age floor.

• What a screening BAER result cannot establish: The exact residual hearing acuity or frequency range in an ear that passes; how well the dog perceives complex speech or ultrasonic sounds; the biological etiology of deafness (inherited pigment-associated degeneration versus acquired intrauterine insult or perinatal ototoxicity); the status of middle-ear mechanics unless bone conduction or tympanometry is added; or a guarantee against future adult-onset hearing loss from chronic infection, ototoxic drugs, noise trauma, or midlife hereditary degeneration.

The University of Florida Small Animal Hospital neurology service emphasizes that clinical BAER screening is fundamentally qualitative, not quantitative. It identifies whether an animal can or cannot hear in each ear, but does not characterize subtle hearing loss thresholds or determine the exact underlying cause. Similarly, Dr. George Strain's extensive genetic research published through Louisiana State University and peer-reviewed journals demonstrates that congenital sensorineural deafness—whether caused by hereditary strial degeneration or prenatal ototoxicity—presents with identical electrophysiologic silence on the tracing.

Result labels: OFA pass/fail, equivocal, and Kennel Club impaired

Depending on the registry and regional protocol under which testing occurs, official BAER reports use distinct nomenclature. Collapsing these regional and institutional frameworks into a generic 'pass' or 'fail' creates substantial confusion, especially when an animal is evaluated for international breeding or registered health databases.

In the United States, the primary registry for congenital auditory screening is the Orthopedic Foundation for Animals (OFA) Congenital Deafness Database. In the United Kingdom, screening follows the Kennel Club BAER Testing Programme developed in collaboration with the Animal Health Trust. While both systems utilize electrodiagnostic click stimulation, their formal administrative labels and threshold allowances differ significantly.

A critical distinction highlighted in the table above is the handling of partial or impaired responses. Under the standard OFA protocol, congenital screening is binary per ear: either an ear demonstrates normal Peaks I and V (Hearing) or it does not (Deaf), with an Equivocal checkbox reserved for technically unsatisfactory tracings. In contrast, the UK Kennel Club protocol instructs testing centers that if a waveform is present but abnormal, the operator must systematically adjust stimulus intensity in increments to identify the lowest decibel level at which Wave V remains discernible, recording an explicit 'Impaired' label with that threshold (for instance, 'Right ear – Pass, Left ear impaired, threshold 55 dB').

The Merck Veterinary Manual notes that unilateral deafness is almost exclusively a BAER-identified condition, never a reliable home-observation identity. Merck lists why behavioral testing cannot identify unilateral deafness: other senses, stress, and lost novelty. A dog that orients poorly to sound may still have one hearing ear. OFA states that a unilaterally deaf dog can be as great a genetic risk as a bilaterally deaf dog; that is a breeding-risk statement, not proof that this tracing showed a specific gene.

What the screening click actually measured

Webb and colleagues (2009) record BAER with three subcutaneous needle electrodes: one at the top of the head, one in front of the ear being stimulated, and a ground either in front of the contralateral ear or over the first thoracic vertebra (T1). Strain's LSU chapter places needles in front of each ear, at the top of the head, and a ground between the eyes or on the neck. OFA requires insert earphones. A masking tone is not considered necessary if recordings use midline and ipsilateral mastoid electrodes; a masking tone is necessary if electrodes are at the vertex and T-1.

OFA's protocol uses at least 200 clicks. Webb notes that several hundred discrete stimuli are averaged so electrical activity not time-locked to the click cancels toward zero, leaving the repeatable auditory waveform. Chemical restraint is optional on the OFA form; Strain states that sedation or anesthesia does not materially affect the BAER. University of Florida holds most animals awake.

OFA judges Peaks I and V present at their appropriate latencies for the equipment used. Those latencies are not a universal millisecond table that an owner can apply from a photocopy. Strain's mapping, which is the mapping this page uses, is:

• Peak I: Produced by the cochlea and auditory nerve. OFA requires Peak I (with Peak V) to be judged present at an appropriate latency. A missing Peak I on a technically adequate trace is the screening identity of an ear that did not respond to that click.

• Later peaks: Strain states that later peaks are produced within the brain. This page does not assign Peak II, III, or IV to named nuclei, and it does not teach owners to localize a brainstem mass from a photocopy. Webb's 2009 methods paper includes a different job: an 8-year-old boxer with only waves I and II and absent waves III–V, used to support a caudal-fossa lesion rather than a simple cochlear flat line.

• Peak V (screening and threshold use): OFA screening asks whether Peak V is present with Peak I at protocol intensity. The Kennel Club impaired path records the lowest stimulus intensity at which Wave V remains discernible. That threshold number is a labeled KC field, not an OFA pass/fail stamp.

Strain: a deaf ear yields an essentially flat line. Merck: pigment-associated cochleosaccular deafness leaves affected ears totally deaf, which is why a loud-click screen can label those ears. A partial or impaired trace points toward a different problem—conductive disease, progressive loss, technical artifact, or a threshold protocol—not a milder form of that congenital phenotype.

graph TD
    A["Acoustic click at protocol intensity"] --> B["Insert earphone"]
    B --> C["Outer and middle ear"]
    C --> D["Cochlea"]
    D --> E["Peak I: cochlea and auditory nerve"]
    E --> F["Later peaks generated within the brain"]
    F --> G["Averaged trace: Peaks I and V judged present or absent"]
    C -. "Wax, debris, otitis" .-> J["Air-conducted trace may be flat or unreadable"]
    D -. "Strial degeneration or hair-cell loss" .-> K["Essentially flat line: no neural peaks"]

A screening BAER still cannot tell an owner what percentage of hearing remains. Strain states that the click contains most audible frequencies of the dog except the very highest, and that BAER is more useful for presence or total absence of auditory function than for quantifying loss in decibels. The Kennel Club public page is explicit: the test does not measure the full range of a dog's hearing and only checks noises in the normal human range; some dogs will test as deaf but can still hear very high-pitched noises. Keep that KC sentence from collapsing into the programme's pass/fail/impaired protocol, which is a laterality-and-threshold packet, not a full audiogram.

A recorded threshold is a different packet from a screening pass/fail. The Kennel Club protocol, when a waveform is present but abnormal, adjusts intensity in increments to the lowest level at which Wave V remains discernible. Merck describes a thorough evaluation for threshold and middle-ear function as BAER threshold testing plus otoacoustic emissions. BluePearl, ranking as an owner explainer rather than a protocol standard, states the procedure takes 5 to 15 minutes, sedation may be used, and if hearing threshold needs to be determined—more often in older patients—general anesthesia is recommended. University of Florida reports about 10–15 minutes per animal for its qualitative screen, with most animals held awake. BluePearl's note that it tests puppies at 7 weeks and may retest toward 16 weeks is that network's practice, not OFA's 35-day floor or one-test-lifetime registry rule.

Air-conducted fail versus bone-conducted repeat

When an ear exhibits an absent waveform on an initial screening trace, the most critical pathophysiologic question is: is the silence sensorineural or conductive?

Sensorineural deafness involves permanent destruction or congenital absence of the cochlear hair cells, stria vascularis, or auditory nerve fibers. In breeds carrying the piebald (s) or merle (M) genes—such as Dalmatians, Australian Cattle Dogs, English Setters, and Boxers—congenital sensorineural deafness arises from strial degeneration: melanocytes within the stria vascularis fail to maintain the endocochlear potential, starving the organ of Corti of metabolic support and resulting in complete, irreversible hair cell death within weeks of birth. In these cases, hearing can never be restored.

Conductive deafness, by contrast, occurs when the cochlea and auditory nerve are structurally sound, but sound waves cannot physically pass through the external auditory meatus or middle ear cavity to vibrate the perilymph. Severe ceruminous impaction, inflammatory exudate from otitis externa in dogs, organisms identified on dog ear cytology, stenosis of the vertical canal, or middle-ear effusion can block or attenuate the air-conducted click enough that an insert-earphone tracing looks flat even though the cochlea may still be intact.

Both the OFA Congenital Deafness protocol and Dr. George Strain's LSU clinical guidelines specifically state that when an ear tests deaf to air-conducted clicks and conductive disease or excess cerumen is suspected, a bone-stimulation repeat should be performed. By pressing an electromechanical transducer directly against the temporal bone, acoustic vibration travels through cranial bone directly to the cochlea, entirely bypassing the external and middle ear.

If bone stimulation elicits a normal BAER waveform with expected latencies, the clinician confirms that the sensorineural apparatus is intact and the deafness is purely conductive. However, Strain notes that many private and mobile screening clinics do not offer bone conduction due to equipment expense and the specialized calibration required. If a young dog with dirty canals or inflamed ears fails an air-conducted screen without bone conduction testing, that flat trace remains incomplete. The proper clinical course is medical management of the canal disease followed by retesting, rather than assuming irreversible genetic deafness.

Age at test, one-test-lifetime, and later hearing change

One of the most frequent administrative and biological misunderstandings in canine audiology involves patient age at testing and the durability of the screening stamp.

Canine puppies are born with immature hearing. Strain states that ear canals do not open until 12 to 13 days of age, and that pigment-associated strial degeneration occurs at about 3 to 4 weeks. Full BAER maturation occurs by 40 days in the dog. Recording to loud stimuli before the canal opens predates the age at which congenital deafness is manifested.

Consequently, testing protocols establish strict minimum age floors:

• OFA Minimum Age Floor: Canines must be at least 35 days of age on the date of evaluation. That is the OFA protocol floor, not a statement that every application for a younger puppy is automatically rejected for a named reason.

• University Neurology Clinic Floors: The University of Florida Small Animal Hospital requires a minimum of 6 weeks of age because hearing pathways are not fully developed earlier; earlier testing is unreliable. Record the dog's age against both the 35-day OFA floor and this 6-week clinic floor rather than declaring one incorrect.

Do not treat a 3-week-old tracing as this protocol. At that age pigment-associated degeneration may still be occurring, BAER has not reached the 40-day maturation Strain describes, and neither OFA's 35-day floor nor UF's 6-week floor has been met.

Equally important is understanding the administrative meaning of OFA's rule that 'one test suffices for the lifetime of the animal.' This rule is a phenotypic registry convention for congenital screening, not a biological guarantee that a dog's hearing can never change. Passing a BAER test at 6 weeks certifies that the dog did not suffer from congenital sensorineural deafness present at puppyhood. It does not grant permanent immunity against adult-onset hearing loss.

Canines can acquire severe or total hearing loss later in life through multiple well-documented pathways:

• Late-Onset Hereditary Deafness: Strain (2015) cites a screening study of 216 adult Border Collies: five dogs from three families, all over 12 years of age, had hearing loss on BAER (one bilaterally deaf, four with reduced hearing). The loss had begun at about 5 years of age, which argued against ordinary presbycusis, and several of those dogs had previously been BAER-tested as hearing. Merck likewise notes hereditary midlife deafness in Border Collie and Rhodesian Ridgeback. That is later-onset biology, not a rewrite of a puppy OFA stamp, and it is not a claim that every breed has adult-onset hereditary deafness.

• Ototoxic Medications: Systemic or topical ototoxic drugs can damage hair cells. Merck lists aminoglycoside antimicrobials (gentamicin, amikacin), antineoplastic drugs (cisplatin), salicylates, loop diuretics (furosemide), and antiseptics (chlorhexidine). That existing furosemide page is adjacent drug-safety reading, not a BAER dosing or treatment plan. Merck: the damage from toxicosis is usually permanent.

• Chronic Otitis Media and Interna: Uncontrolled middle ear infections can erode the round and oval windows, causing infectious labyrinthitis that permanently destroys the cochlea and vestibular organs (often co-presenting with acute signs of vestibular disease in dogs).

• Presbycusis and Environmental Trauma: Age-related sensorineural degeneration (presbycusis) is extremely common in geriatric dogs, typically beginning with high-frequency loss and progressing to conversational sound levels. Acute acoustic trauma, head trauma, and complications during prolonged deep anesthesia can also induce sudden hearing loss.

Finally, owners must remember that a BAER pass is not a DNA test, and a DNA test cannot replace BAER. In pigment-associated breeds, inheritance is complex; hearing parents can still produce affected puppies (Kennel Club; OFA/Strain). Merck states DNA testing is available only for some forms (nonsyndromic deafness in Rottweilers, LOXHD1; hereditary deafness in Doberman Pinschers, including PTPRQ; the chapter also cites MYO7A). BAER and informed breeding remain the usual screening tools for pigment-associated breeds. Do not mark an OFA pass as genetically clear.

Owner records to keep with the result

Whether acquiring a newly screened puppy from a breeder or taking a patient to a specialty referral center, maintaining a complete, verifiable paper and electronic trail is essential. A verbal statement that 'the litter passed BAER' or an unannotated photocopy of a waveform without verifiable patient identification carries no official registry standing.

Ensure your permanent veterinary records folder contains the following eight indispensable documentation components:

1. The Original Printed Tracing: The physical printout or PDF from the machine. OFA requires a printed copy of the BAER tracing that contains the dog's name or identification linking it to the application, provided to the owner and to OFA. Keep the per-ear label, stimulus intensity in dB nHL, and whether the trial was air- or bone-conducted. Mark missing fields missing.

2. Identity-Linked Trace Heading: The printed tracing itself must carry the dog's registered name, microchip number, or litter identifier printed directly on the machine output at the time of testing. Unlabeled strips of paper cannot be reliably matched to an individual animal.

3. Ear-by-Ear Outcome Designation: Clear, unambiguous recording of laterality: Left Ear (Hearing / Normal vs. Deaf vs. Impaired) and Right Ear (Hearing / Normal vs. Deaf vs. Impaired), accompanied by the stimulus intensity used for each trial.

4. Stimulus Modality Specification: Explicit notation that testing was conducted via insert earphones (air conduction). If bone conduction was performed, the transducer site and resulting waveform must be documented separately.

5. Tester Identification & Professional Credentials: The signature, printed name, and role of the evaluator. OFA recommends board-certified veterinary neurologists and accepts experienced veterinarians, neuroscience professionals, and audiologists. For Kennel Club database publication, if the tester is not MRCVS, a second reviewer is required and at least one reviewer must be MRCVS.

6. Verified Permanent Identification: The dog's microchip or tattoo number scanned and verified immediately prior to electrode placement. In OFA registration, if an animal lacks verified permanent ID at the time of evaluation, the resulting certificate carries a 'NOPI' (No Permanent Identification) suffix. For UK Kennel Club database publication, microchip scanning at the test is mandatory.

7. Registry Application Copy & Submission Custody: At teaching institutions like the University of Florida, the clinic provides the owner with the completed OFA application form and test tracing; submitting that paperwork with the required registry fee to OFA headquarters is the owner's responsibility. Retain a photocopy of the signed application before mailing.

8. OFA Public Release Authorization: On the official OFA application, owners must review the open database authorization. By default, OFA only publishes normal (passing) results. If a dog tests unilaterally or bilaterally deaf, that abnormal result will only appear in the public database if the owner explicitly initials the release authorization on the form.

A fictional one-report identity check

To illustrate how to review an actual paperwork packet and separate confirmed physiological facts from unknown variables, consider the following simulated, clearly labeled fictional case report. This scenario is entirely fictional, does not represent a real patient, clinic, or registry entry, and serves strictly as an educational worksheet model.

Case Profile: Fictional canine Echo, a 6-week-old (42-day) female companion puppy presented for a screening packet. The owner received a paper copy of the tracing and an OFA Congenital Deafness application. This packet is stamped fictional: no real kennel, no real OFA number, no clinic price, and no treatment plan.

By methodically auditing the packet against this worksheet, the owner immediately extracts three vital insights:

1. The labeled screening result is unilateral (left ear air-conducted fail, right ear hearing): The right ear produced Peaks I and V at 85 dB nHL. The left ear remained flat at 85 dB and again at 100 dB nHL. Bone conduction was not offered, so this packet does not prove cochlear degeneration even with clear otoscopy. Strain notes that unilateral deafness does not pose the household liabilities of bilateral deafness; this page does not prescribe training. OFA still records unilateral deafness as a fail for bilateral hearing.

2. Unknown fields remain unknown: The report confirms what the ears heard on day 42, but provides zero information regarding why the left ear failed. It does not prove a specific hereditary gene mutation, nor does it guarantee that the right ear will maintain perfect hearing into old age.

3. Administrative custody rests with the owner: Having the paperwork in hand does not automatically register the puppy with OFA. The owner must submit the documentation and decide whether to authorize release of the abnormal result to the open research database.

Sources

The analysis and procedural criteria presented in this guide are drawn from authoritative veterinary academic neurology services, peer-reviewed clinical research, and established breed registry protocols:

1. Orthopedic Foundation for Animals: Congenital Deafness. Phenotypic database protocol, 35-day minimum age requirement, 70–105 dB nHL click stimulus guidelines, and lifetime-one-test registry policies.

2. Orthopedic Foundation for Animals: Application for Congenital Deafness Database. Clinic-hosted copy of the OFA application (folder dated July 2026), not OFA's own domain. Fields include identification, left/right ear and dB, Equivocal as a separate box, and public-release initials for abnormal results.

3. Orthopedic Foundation for Animals: Our Fees. Official registry fee schedule documenting the $15 per-dog database application fee and breed foundation grant arrangements.

4. Louisiana State University School of Veterinary Medicine (Dr. George M. Strain): Congenital Deafness and Its Recognition. Detailed review of electrophysiologic mechanics, Peak I through V origin, click stimulus limitations, 40-day neural maturation, and strial degeneration.

5. Louisiana State University School of Veterinary Medicine (Dr. George M. Strain): What is Bone Stimulation?. Clinical mechanics of electromechanical bone transducers, bypassing conductive middle-ear barriers, and equipment limitations across screening facilities.

6. Strain GM. Canine deafness. Vet Clin North Am Small Anim Pract. 2012. Comprehensive review of congenital sensorineural deafness, conductive etiologies, eye color associations, and electrodiagnostic standards.

7. Strain GM. The Genetics of Deafness in Domestic Animals. Front Vet Sci. 2015. Genetic mechanisms of cochleosaccular and neuroepithelial deafness, complex inheritance patterns, and documentation of adult-onset hearing loss in Border Collies.

8. Webb AA, et al. Brainstem auditory evoked response (BAER) testing in animals. Can Vet J. 2009. Clinical methodology of veterinary BAER recordings, electrode montages, signal averaging, and wave interpretation.

9. Merck Veterinary Manual: Deafness in Animals (reviewed August 2025 by Peter Scheifele; last updated April 2026). Textbook reference covering congenital versus acquired deafness, limits of behavioral hearing testing, DNA test availability (LOXHD1, PTPRQ), and threshold evaluation.

10. University of Florida Small Animal Hospital, Neurology: What to Expect: BAER Hearing Test. Clinical expectancies for patient screening, 6-week age floor, qualitative screening limits, and client paperwork custody.

11. The Kennel Club (UK): BAER testing. Official UK health screening programme overview, published result classifications (Unaffected, Affected–unilateral, Affected–bilateral), and microchip verification rules.

12. The Kennel Club (UK): BAER Programme Best Practice Testing Protocol. Standard operating procedures for testing centers, 70–80 dB baseline stimuli, 15–20 dB confirmation increases, and the Wave V threshold protocol for impaired ears.

13. BluePearl Pet Hospital: BAER Test for Hearing Loss. Veterinary specialty explainer covering owner expectations, patient restraint, canal inflammation interference, and general anesthesia for adult threshold studies.