Question about excessive white

[Rave]

Will a pup with excessive white (i.e. head and ears are colored and rest of body is white) have a higher risk of potential hearing or sight problems? There is no merle in either parents.

 

I only ask because on the BCSA site (because where else are you going to read about color?), I ran across this: "there is research-linking deafness to the alleles for piebald spotting or extreme whiteness."

 

Thanks!

[Laurae]

I would look at the lines, whether there is any history of deafness in the lines of the pup.

[Mark Billadeau]

This is an epidemiological study looking for a possible correlation between excessive white, eye color, and coat color with congenital deafness. There was some correlation between congenital deafness and blue eye(s) and excessive white.

 

Prevalence of Unilateral and Bilateral Deafness in Border Collies and Association with Phenotype

 

The correlation was not 100%. A hypothesis was described to me which may explain why there wasn't a 100% correlation. The hypothesis suggests that if any of the pups in a litter have excessive white or two blue eyes all the pups in the litter are at increased risk of congenital deafness. The hypothesis fits with outcomes of litters I have seen where there was congenital deafness.

[Rave]

Thank you for the link Mark. One question though, was the excessive white to which the study referred on the head or the body? The results stated:

 

"Deaf Border Collies had higher rates of merle coat pigmentation, blue iris pigment, and excess white on the head than normal hearing Border Collies (all P , .001)."

 

and

 

"However, all Border Collies are homozygous for the sw and sp alleles so that the S locus is not thought to be involved in the regulation of deafness in Border Collies.23"

 

The above passages made me think it was just the head and not the body, so please correct me if my understanding is faulty. Also, it is my understanding from very limited research today that the S locus is the one affecting pattern white on the body, and more specifically the sw allele accounts for "excessive" white (e.g. colored head on all-white body).

 

I would appreciate any guidance on understanding the study results since I am not a scientist. Thank you!!!

[juliepoudrier]

I haven't read the study to which Mark linked, but if anyone still subscribes to the belief that there's a correlation between deafness and lack of pigmentation in hair cells of the inner ear, then I would expect that white-headed dogs would be more likely to express congenital deafness than color-headed dogs. At least congenital deafness can be discovered before a pup ever goes to a prospective owner, if the breeder tests the pups.

 

J.

[Maja]

Sometime ago, I talked to a geneticist in relation to white on my Cameroonian sheep, and he said that there are at least three different "white" genes, so that's why some white have the problem some do not. Some of the white genes are recessive, others are dominant.

 

The study posed a hypothesis linking deafness due to the merle gene, and the research in this article supported the hypothesis. It did not study white related to other whites, e,g, the white that BCs have in their black and white markings, which is of different genetic origin than the white resulting from merle.

 

Maja

[Mark Billadeau]

This is from the Materials and Methods section of the article.

Phenotype Recording

Phenotypic markers were recorded, which included coat color,

sex, and iris color. In addition, dogs with excess white pigmentation

(subjectively estimated at more than 50% of the head) were noted.

Coat color was recorded as one of the following possibilities:

black and white; black, white, and tan; red and white; red, white,

and tan; blue and white; blue, white, and tan; blue merle; red merle;

predominantly white; and any other color. For the purposes of

analysis, coat color was classified according to the dominant color:

black, blue, red, or merle. Dogs who had white as the dominant

color were allocated to the color group of their existing pigmented

areas. Sex was recorded as male or female; if an adult had been

neutered, then this was also recorded. Iris color was recorded as 2

brown eyes, 1 blue eye, or 2 blue eyes; if a dog's iris was partially

blue, then this was also recorded.

[Maja]

I am sorry. It did study other whites, and the indication for for the merle link with deafness.

 

Mark,

Thank you for correcting me.

Maja

[Mark Billadeau]

The study posed a hypothesis linking deafness due to the merle gene, and the research in this article supported the hypothesis. It did not study white related to other whites, e,g, the white that BCs have in their black and white markings, which is of different genetic origin than the white resulting from merle.

 

Maja

Actually the article lists the aims of the study,

The aims of this study, which is part of a larger

investigation into congenital deafness in Border Collies,

were the following: (1) to report the prevalence and sex

distribution of unilateral and bilateral deafness in

Border Collies by using BAER and clinical observations;

(2) to quantify how deafness varied with other phenotypic

attributes, including coat pigmentation and iris

color; and (3) to investigate relationships between

parental and offspring hearing status.

 

The study aims was based upon these observations listed in the introduction.

 

In fact, more than 60 breeds of dog have

now been identified as suffering from congenital

sensorineural deafness,17 including the Border Collie.

Most of these breeds carry the alleles s^p for piebald

spotting or s^w for extreme white piebald coloring; both

of these alleles are thought to be carried by the Border

Collie.17 Border Collies also carry the dominant merle

gene M,17 another pigmentation allele associated with

deafness.

An association between blue eye color and congenital

deafness has been recognized for over 100 years.17

Studies carried out on Dalmatians with blue eyes

showed that there was an increased prevalence of

congenital deafness in dogs with one or more blue

eyes.14,17 The lower prevalence of congenital deafness in

Dalmatians in the UK, where blue-eyed dogs are not

allowed for breeding, seems to support this.5,810,13 Blue

eyes are accepted in the breed standard for Border

Collies with a merle coat color.

 

This indicates the authors were looking for association of congentical deafness with:

piebald spotting

extreme white piebald coloring

dominant merle gene

blue eye color

gender

 

Sorry, I was working on this while Maja was posting.

[Mark Billadeau]

The hypothesis that was posed to me (see above) would imply that the gene(s) involved with congenital deafness are associated with the gene(s) which produce the colorations with some correlation with deafness (excessive white on head, 2 blue eyes, and possibly merle and 1 blue eye). While those dogs with these colorations may not be "affected" (deaf) they could be carriers of the gene(s) for congenital deafness.

 

Until this is proven and there is a test for the gene(s) for congenital deafness, it is my personal opinion (not an official opinion) that care should be taken when breeding two dogs when both have the colorations that have some correlation with congenital deafness. I'm not advocating to not breed these dogs, just take care when selecting crosses and look for deafness in any pups in a litter where one of these phenotypes (excessive white on head or 2 blue eyes) is present in any of the pups.

[greg l]

Mark, rave and everybody else....

 

I have posted before about my Red/White deaf male. He has been completely deaf since birth. He has maybe 10-15 percent white on his head, red ears{ no white hairs} and black eyes. We bought him from a backyard breeder who is not forthcoming about his background. In fact when we contacted her to let her know he was deaf her statement was " if you bring him back I will put him down". She will not give us papers...numerous phone calls and letters...so we are clueless. We did nueter him because we did not want him to have the ability to pass on his deafness to any one else...

 

As a pet and a border collie on a farm with only horses he is a fantastic dog. So as to the study...he is mostly red...in fact his entire body is only about 15 per cent white...I don't know how this fits in but I thought I would let you all know about our boy...thanks...Greg