Freethought & Rationalism Archive

ShavenYak · 09-07-2007, 11:16 AM

Quote:

Originally Posted by doghouse

The risk of deafness depends on how strongly the gene is expressed. For example, dalmatians with blue eyes (strong piebald expression) are statistically more likely to be deaf.

When I was a kid, we had a dalmatian with one blue and one brown eye. How does that end up happening? Come to think of it, her hearing wasn't that good, by dog standards. Perhaps she was deaf on one side.

RAFH · 09-07-2007, 11:35 AM

Quote:

Originally Posted by Tao of Pooh

Quote:

Originally Posted by Codec

Why? A chromosome is like a book of recipes. It just happens in this case that the recipe for sex determintation is in the same book that has the recipe for fur colour.
The X chromosome has all sorts of things on it - in humans it has the genes for colour-pigments in the eye, such that males can often be colour blind when they are defective (females have a spare copy).

In this case, one X chromosome contains one of the colours for calico, and the paired other X contains the other colour. Hence males can't express it as they only ever have one X chromosome, except for rare mutations where the get an extra X such as XXY (which are usually sterile).

Have looked into your other questions (I like a challenge).
White/blue eared is a problem with the way the embryo tissues are formed apparently, giving both the blue colour and malformed ear parts.

Polydactyl cats are just a mutation, and it can be inherited. Its recessive though, so you need to polydactyls to breed more for certainty.

So the white & blue-eyed thing is a fallacy? I've never had a white cat so I didn't know that, I guess it's just one of those things you hear for so long you don't question it anymore...thanks.

Quote:

I love your end quotes BTW.

Thanks again, I've rec'd several complimentary PMs about them.
I'm anticipating yet another not-complimentary PM from a mod/admin about them soon

Some people see things that are and ask, Why?
Some people dream of things that never were and ask, Why not?
Some people have to go to work and don't have time for all that shit.

No, the white cat/blue eyes deafness is a real syndrome. Had a white cat with one blue eye and the other gold, was deaf as a stone. Freaked out the dogs something fierce, they couldn't figure out why he wouldn't run when they'd come up to him barking like crazy. Then he'd notice them and take a swipe, often removing parts of the dog's nose.

Again, it's a relationship between the coloration genes and the ear genes.

doghouse · 09-07-2007, 12:35 PM

Quote:

Originally Posted by ShavenYak

When I was a kid, we had a dalmatian with one blue and one brown eye. How does that end up happening? Come to think of it, her hearing wasn't that good, by dog standards. Perhaps she was deaf on one side.

The coat color of dalmations is kind of complicated because it involves several interacting genes, some of which have not yet been mapped. First the underlying coat color (black or brown/liver) is determined by genes that dictate the type of melanin produced.

Then the extreme piebald allele of the Piebald locus covers the color with white and the ticked allele of the Ticking locus allows the underlying color to show through in certain areas -- the dark spots.

Where the spots are located on the body seems to be somewhat random, although it has to do with migration of melanocytes down from the spinal column during growth (dalmations are born white). But however this works also applies to the eyes (and inner ears). That's why you can get one or both blue eyes and deafness in one or both ears.

DrJim · 09-07-2007, 07:14 PM

Why do cats always have ears tha tlook a little decayed? A part of the ear looks a little leprous. Seen it on every cat I've come accross.

Tao of Pooh · 09-08-2007, 12:38 AM

Quote:

Originally Posted by Daisy

Quote:

Originally Posted by Tao of Pooh

So the white & blue-eyed thing is a fallacy? I've never had a white cat so I didn't know that, I guess it's just one of those things you hear for so long you don't question it anymore...thanks.

No, read the article. It said that there is a strong, well-known link BUT both blue eyes and white color can be caused by more than one gene combo, so it depends on the genotype not the phenotype.

Yeah, it did say there's a strong link but not an automatic link between white fur/blue eyes & deafness; I thought it was an always thingie, that all white/blue-eyed cats were deaf. I guess I just worded my reply wrong.

I didn't get to read the whole thing, I'm @ work & it gets really busy in here. I read bits o' it.

You know everybody is ignorant, only on different subjects.

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09-07-2007, 07:14 PM	#14
DrJim Regular Member Join Date: May 2003 Location: Lethbridge AB Canada Posts: 445	Why do cats always have ears tha tlook a little decayed? A part of the ear looks a little leprous. Seen it on every cat I've come accross.

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