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Cluj Vet J 2021, 26, 2 http://clujveterinaryjournal.ro 

Communication 

Brain auditory evoked response test, the standard method for the 
diagnosis of the hereditary deafness in dogs  
Nicolae Coldea 1,* 

1 ”Dr Coldea Nicolea’’ private practice, 1C Tudor Arghezi St., Sibiu, Romania: coldeadvm@yahoo.com 
* Correspondence: coldeadvm@yahoo.com;  

Abstract: Hearing deficiency is one of the most common hearing impairments that affect humans and other mammalian alike. Hear-
ing loss is not painful or a life-threatening change but can endanger the patient by taking into account a large number of breeds 
predisposed to hereditary deafness, this short communication aims to synthesize the steps and the method for BAER test. For the 
affected breeds, the	BAER	test	is	recommended	starting	at	the	age	of	two	months. 

Keywords: BAER, dog, auditory evoked response test 
 

1. Introduction 
Dog breeds that are affected by hereditary deafness: Akita,  Dalmatian,  Nova Sco-

tia, Duck Tolling Retriever,  Alapaha Blue Blood Bulldog/Otto Bulldog,  Dappled 
Dachshund,  Old English Sheepdog, American Bulldog , Doberman Pinscher,   Papil-
lon,  American-Canadian Shepherd,  Dogo Argentino,  Pekingese,  American Eskimo,  
English Bulldog,  Perro de Carea Leones,  American Hairless Terrier, English Cocker 
Spaniel,  Pit Bull Terrier,  American Staffordshire Terrier,  English Setter Pointer/Eng-
lish Pointer,  Anatolian Shepherd,  Foxhound,  Presa Canario, Australian Cattle Dog, 
Fox Terrier, Puli,  Australian Kelpie,  French Bulldog, Rhodesian Ridgeback,  Austral-
ian Shepherd, German Shepherd,  Rat Terrier,  Australian Stumpy-tail Cattle Dog, Ger-
man Shorthaired Pointer,  Rottweiler,  Beagle, Goldendoodle,  Saint Bernard, Belgian 
Sheepdog/Groenendael,  Great Dane, Saluki,  Belgian  Tervuren,  Great Pyrenees, 
Samoyed,  Bichon Frise,   Greater Swiss Mountain Dog,  Schnauzer  Border Collie  
Greyhound  Scottish Terrier  Borzoi Havanese  Sealyham Terrier  Boston Terrier, Ibi-
zan Hound,  Shetland Sheepdog,  Boxer,  Icelandic Sheepdog,  Shih Tzu, Brittney 
Spaniel,  Italian Greyhound,  Shropshire Terrier, Bulldog Jack/Parson Russell Terrier,  
Siberian Husky, Bullmastiff,  Japanese Chin,  Soft Coated Wheaten Terrier, Bull Terrier,  
Keeshond,  Springer Spaniel,  Canaan Dog, Kuvasz,  Sussex Spaniel,  Cardigan Welsh 
Corgi,  Labrador Retriever,  Tibetan Spaniel,  Catahoula Leopard Dog,  Lhasa Apso, 
Tibetan TerrierCatalan Shepherd LowchenToy Fox Terrier  Cavalier King Charles Span-
iel Maltese,  Toy Poodle, Chihuahua,  Manchester Terrier, Walker American Foxhound,  
Chinese Crested  Miniature Pinscher,  West Highland White Terrier,  Chow Chow,  
Miniature Poodle, Whippet, Cocker Spanielmongrel, Yorkshire Terrier,  Collie,  New-
foundland Landseer,  Coton de Tulear, Norwegian Dunkerhound [1]. 

For these dogs, the BAER test is recommended starting at the age of two months. 
This paper aims to describe the technique of the test and the interpretation of the 

results. We will not insist on the etiology of deafness as it is described elsewhere [2,1,3]. 
However, some elements of classification, anatomy, physiology, and genetics are neces-
sary. 

 
 
 
 

Received: 08.05.2021 

Accepted: 03.09.2021 

Published: 29.092021 

DOI:10.52331/cvj.v26i2.23 

 

 

 

Copyright: © 2021 by the authors. 

Submitted for possible open access 

publication under the terms and 

conditions of the Creative Commons 

Attribution (CC BY) license 

(http://creativecommons.org/licenses

/by/4.0/). 



Cluj Vet J 2021, 26, 2 25 
 

2. Deafness 

Deafness can be peripheral or central, congenital / inherited or acquired, uni- or bilateral, total or partial, 
conductive or neurosenzorial. 

The congenital deafness should not be confused with the hereditary one; the congenital form may appear 
during parturition and is determined by dystocia and oxygen deprivation. Hereditary deafness occurs 3 to 4 
weeks after birth and is a neurosensorial type. It is the result of the degeneration of a structure called stria 
vascularis. This structure is responsible for maintaining a very specific composition of the endolymph from 
scala media, characterized by a high concentration of potassium ions and a low concentration of sodium ions, 
different from other extracellular fluids inside the body. This process is involved the numerous melanocytes 
present in stria vascularis[3,4]. 

When the atrophy of the stria occurs and/or the melanocytes are missing, the composition of the 
endolymph is altered and leads to the death of the hair cells from the organ of Corti. The hair cells are the ones 
who transformed the sound (mechanic oscillations) transmitted to the cilia by the tectorial membrane in 
electric impulses. When these structures are damaged, peripheral neurosenzorial deafness appears.  

A different situation is described in Dobermans when the hair cells die, but the melanocytes from stria 
vascularis are intact, called neuroepithelial deafness [5,6]. 

The inheritance of deafness is controlled by a gene situated on Merle (M) locus, with two alleles: the 
recessive m and the dominant M. The homozygous MM individuals present blue irises and may be blind and 
sterile. Unfortunately, heterozygous Mm x Mm parents will give birth to 25% MM puppies. 

Another gene is placed on the S locus, and it is called piebald. It has four alleles: dominant (S) and recessive 
(si) Irish spotting, (sp) piebald, and (SW) extreme white piebald. The inheritance mechanism is considered to 
best fit by the presence of two autosomal recessive genes or an incompletely penetrant recessive allele. 

Regarding the deafness in Dobermans, the inheritance has an autosomal recessive mechanism [3]. 

3. BAER test 

According to the ”Orthopedic Foundation for Animals," the only accepted test (at least for the moment) to 
detect hereditary deafness in dogs is the BAER (Brain Auditory Evoked Response) test.  

Headphones deliver the test sound and one ear at a time test can be diagnostic for other types of acquired 
deafness (toxic, traumatic, degenerative, inflammatory, etc.) (fig. 1). It is recommended to perform the test at 
the age of two months. The test shows a few waves, and the first five ones are of diagnostic importance. The 
waves are marked with roman numbers (fig. 1). 

Wave I is generated by the distal end of the cranial nerve VIII, wave II by the proximal part of cranial nerve 
VIII, wave III by the cochlear nucleus, wave IV and V inferior colliculus, and probably by the medial geniculate 
body. Anyway, the disturbances responsible for altering the last two waves will determine other symptoms 
of diseases of the central nervous system. 

The test can be done without sedation, but if the patient is restless, it can be sedated because the medication 
does not affect the test result. Currently,  we are using four electrodes: one "grounding" electrode at the level 
of the T1 vertebra, one positive electrode on the median line of the skull at the level of the ears, and two 
negative electrodes anterior to the tragus of each ear. 

. 



Cluj Vet J 2021, 26, 2 26 
 

	
Fig. 1 Positioning of headphones in BAER test 

	

	
Fig. 2 Right ear deafness. 

I II 



Cluj Vet J 2021, 26, 2 27 
 

	
Fig. 3 Bilateral deafness. 

 
To avoid motion artifacts, sedation of the patient is recommended. 

	
Fig. 4 Motion artifact 

	
Fig. 5.  Same patient after sedation. 

 

4. Discussion 
Identification of the dogs (e.g., microchip) is very important because uni- or bilateral deaf dogs must 

be excluded from breeding. Puppies with unilateral deafness can be excellent pets, but those with bilateral 
deafness need special attention. These dogs can be good companion animals, but care should be taken to 
avoid unattended contact with other persons or animals. Because they cannot hear, they may have a violent 
reaction when touched without warning. Anytime someone wants to pet the dog, he should be sure that he 
is within the visual range of the affected dog. It is recommended to provide these patients with collars or 
harnesses with warnings (e.g., Don't touch! Deaf dog!) One can find/buy this type of equipment in pet shops 
or on the internet. It is highly recommended to use them, to avoid accidents. 



Cluj Vet J 2021, 26, 2 28 
 

Conflicts of Interest: None 

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