Deafness in English Setters

Deafness is another common inherited problem in English Setters. Dr. George M. Strain's database of 662 English Setters reports 2.1% totally deaf (both ears) and 10.3% unilaterally deaf (one ear). The English Setter Association of America BAER database, which has more dogs, shows a lower incidence of 5.6% unilateral and 1.3% bilateral. The ESAA database is voluntary so it's possible some deaf dogs are not being reported, which would make the numbers biased toward hearing dogs. Either way a significant number of English Setters are deaf. It occurs in show dogs and all types and lines of field English Setters.

Inheritance of Deafness

The way English Setters inherit deafness is not clearly understood, but it is related to the white spotting or piebald series of genes in the breed. The piebald genes control the amount of solid dark (black or brown) patching a dog has. These genes cause white spots that cover the underlying black or brown pigment.

In English Setters the white spotting covers all or most of the dog, typically resulting in either no solid dark patches or only head patches. Ticking comes from a different gene which allows small dots of the underlying black or brown color to show through the white. Deafness related to the white spotting genes is caused by lack of pigment, and subsequent atrophy, of certain structures of the inner ear, which occurs by four weeks of age.

Breeds with extreme white piebald genes have a high incidence of deafness- Dalmatians are the poster child breed for this problem. Studies done on Dalmatians show a strong association between deafness and three pigment characteristics which indicate a strong expression of extreme white: lack of solid patches, blue eyes, and missing pigment on the tapetum in one or both eyes. The strongest association is with patching. Although the presence of patches doesn't guarantee a dog can hear, dogs with no solid patches of color have a significantly higher incidence of deafness.

Unfortunately data on patching has only been collected for Dalmatians, but according to the leading researcher on the subject there is every reason to expect the same association in English Setters and other breeds that also carry piebald genes. This is supported by the fact that blue eyes have been shown to be associated with deafness in English Setters and English Cocker Spaniels.

Some people believe that dogs with missing eyelid pigment or overall light ticking are more likely to be deaf, but studies in Dalmatians have shown no association. The color of the dog- blue, orange, or tricolor, has no relation to deafness.

Breed Standards and Deafness

A common misconception widely circulated in English Setter circles is that lack of patching is not related to deafness in this breed. Even though studies in Dalmatians make it clear that selecting for no solid patches is also selecting toward deafness some people still proclaim that patches don't matter in English Setters. There is NO data to back up that belief and anyone who says this has not studied the problem or is ignoring the facts.

People don't want to believe that what they consider to be a desirable appearance might be detrimental to the breed, but in this case it is. Although the English Setter breed standard doesn't disqualify patched dogs un-patched competitors are heavily favored, which encourages the selection of dogs with no patching. In Dalmatians patches are not allowed at all. The result is a breed at the extreme white end of the piebald series of genes with a deafness rate of 30%. If the breed clubs wanted to get serious about reducing the incidence of deafness, an effective approach would be to require patching in their breed standards.

What Breeders Can Do

There are currently studies underway to try to locate defective genes that cause deafness. Hopefully there will eventually be a DNA test to screen for carriers. In the mean time there are two things a breeder can do to reduce the incidence of deafness- select for patches and use dogs with normal hearing.

The hearing status of a breeding dog is an important factor in predicting whether it will produce deafness in it's offspring. Deaf or unilaterally deaf dogs are much more likely to produce deafness than normal hearing dogs are. Many unilaterally deaf, and even some totally deaf dogs, compensate well enough that it is impossible to diagnose the deafness without a hearing (BAER) test. Watching puppies carefully to see if they respond to noises and consistently look the correct direction is helpful, but not foolproof. Bilaterally deaf puppies are obvious when young if you know what to look for but some unis cannot be identified with behavioral tests.

Breeders are often unaware they own or have sold deaf dogs, and deafness is often interpreted as the dog being stupid. An old friend of ours who had Rymans all his life used to tell us "They have been great dogs, but every once in a while you get a stupid one that just can't learn anything". These were almost certainly deaf dogs.

Buyers should ask breeders if their dogs have been BAER tested and buy pups from parents who have tested normal. Ideally pups should be tested before being sold. Unfortunately there are very few BAER testing centers and for some breeders the closest one is too far to travel with young pups. In that case ask what the breeder does to watch for bilaterally and unilaterally deaf puppies.

Anyone who wants to learn more should read the following articles:
http://www.lsu.edu/deafness/VetJDeaf2004.pdf
http://www.lsu.edu/deafness/recent.htm