Lethal guinea pigs discussion

[Slap Maxwell]

PEW= Pink Eyed White.

How did the mother get pregnant? Do you have pictures of the parents?

[pinknt]

Oh right, yes its not all white. I suppose it must just be an injury or something. Thanks - I also heard that somebabies can be born withan eye which appears blind, but then heals itself after a few weeks - do you know what this is?

[Slap Maxwell]

I am not totally sure on that.

[salana]

You have a 25% chance or getting a lethal if these types are bred. (dalxdal or roanxroan)

More like each baby has a 25% chance of being a lethal. With a larger litter, you get over a 50% chance of having at least one lethal. (I did the math a while back but don't remember--basically your chance of getting lethals is 1-(.75^N) where N is the number of babies in the litter.)

Also, since roan and dal are genetically the same, roan x dal will produce lethals.

Lethals are always all white and usually have pink eyes, although some have dark eyes and some have none. But if your pig has any pigmentation of skin or hair he can't be a lethal.

[Slap Maxwell]

Really, a roan and dal can produce a lethal? That is interesting, I wasn't aware of that.

[salana]

They're both Rnrn. The only difference is whether the colored hairs are clumped together or spread out more. I imagine other genes control the amount of clumping.

[Erin8607]

How does the eye appear "blind"?

It could be entropion, where the lids grow inward toward the eyeball making lacerations in the cornea.

I had a baby born with this in my rescue from a highly inbred group of pregnant sows that I took in. The condition is very painful and generally does not heal on it's own. If enough irritation is there, the eye could rupture.

We had this baby diagnosed then he went under to have an "eye lift" at 15 days old. He's about 5 months old now and has had no problems since his surgery. All damage to the eye healed over after the problem was corrected surgically.

I highly suggest a trip to a knowledgable vet to have a look at the eye. Also to seperate your adult guinea pigs if you are unsure of their sex or if you have bought a male/female. Breeding is very risky to sows and babies.

[pinknt]

I took it to the vet today- got eye drops for it, so we are just seeing how it goes.

[Matt & Guins]

Originally Posted by salana

More like each baby has a 25% chance of being a lethal. With a larger litter, you get over a 50% chance of having at least one lethal. (I did the math a while back but don't remember--basically your chance of getting lethals is 1-(.75^N) where N is the number of babies in the litter.)

Regardless of whether it is a big litter or not, there is still a 25% chance of having a "lethal" born in a litter.

25% chance of lethals, 50% chance of roans or dallies (depending on which was bred) and 25% chance of the self counterpart.

In saying this, you could have all or no micros born.

Originally Posted by salana

Also, since roan and dal are genetically the same, roan x dal will produce lethals.

Roans and dalmations are NOT genetically the same. They belong to the same gene series, but a different allele.

WhWh - Anopthalmic White Cavy

Whwh - Dalmation Cavy

whwh - Non Dalmation/Roaned Cavy (self or ticked)

whmiwh - Roaned Cavy

whmiwhmi - Microthalmic White Cavy

Whwhmi - Roaned/Dappled cavy

Very dappled roans, or very roany dalmations can appear similar - but genetically they are still very different and can NOT produce "lethal" babies.

I hope this clears things up


Matt

[Slap Maxwell]

The gene is acctuallly the Rnrn gene.

Salana is an expert with lethals.

[Matt & Guins]

Originally Posted by slap_maxwell

The gene is acctuallly the Rnrn gene.

In some countries it is reffered to as the "Rnrn" gene.

Here in Australia it is the "Wh" gene - They are not exactly the same - as the "Rn" is the very simplified way of explaining it and "Rn" doesnt have as many alleles.

Rn is what the US have used since the dawn of time. Most other places tend to use Rs or Wh - or Si for roans.

The information I originally quoted are from well known geneticists Roy Robinson and Cathy Whiteway"


Matt

[salana]

Do you have any links to sources?

Even if roan and dal are caused by different alleles, having two different broken alleles and no ordinary ones will cause problems.

Your statistics are incorrect. Each baby has a 25% chance (1 in 4) of being a lethal, and a 3 in 4 chance of not being a lethal. Each baby's genetics are determined independently, so you simply multiply the probabilities together. So to get the chances of having a litter of 4 lethals, you multiply 1/4 by itself 4 times, and get 1/256. To get a litter of 4 non-lethals, you multiply 3/4 by itself 4 times, and get 81/256, which is far less than 1/2.

It doesn't matter what you call the gene (are you guys saying it's the same as Wh in rats and mice?) it still goes by Mendelian inheritance patterns.

[Matt & Guins]

Originally Posted by salana

Do you have any links to sources?

The information are from books published - "Colour Inheritance in Small Mammals" by Roy Robinson and "Colour Genetics of Cavies" by Cathy Whiteway.

May I ask which sources you are going by? I would be very interested in reading up on them to see how our ideas are similiar and differ, and to come to some sort of conclusion.

Originally Posted by salana

Your statistics are incorrect. Each baby has a 25% chance (1 in 4) of being a lethal, and a 3 in 4 chance of not being a lethal. Each baby's genetics are determined independently, so you simply multiply the probabilities together. So to get the chances of having a litter of 4 lethals, you multiply 1/4 by itself 4 times, and get 1/256. To get a litter of 4 non-lethals, you multiply 3/4 by itself 4 times, and get 81/256, which is far less than 1/2

I'm not arguing that on paper 1:4 could be "lethals", cause on paper thats true, but you could still get a whole litter of them, or none at all born.

Originally Posted by salana

It doesn't matter what you call the gene (are you guys saying it's the same as Wh in rats and mice?) it still goes by Mendelian inheritance patterns.

Wh in rats is not the same as Wh in cavies - for example, the satin gene is written as N, Sa, Sn to name a few. Himalayans as ch and ca, and unless you want to get your cavies' genes mapped in a lab you have no way of proving what genotype your cavies have as there are many different mutations of the same gene.


Matt

[salana]

I started by reading this site, then learned more about similar genes in other animals by starting at http://www.ratbehavior.org and emailed the geneticist who had written their genetics stuff, then searched databases of genetics papers (of which there are none about cavies)... I googled for your sources but was unable to find any mention of them, except one site said a MSN group had the "Color Genetics in Cavies" as a file, but I couldn't find it on their homepage.

From my reading, I have a hypothesis that the gene in question codes for MITF. Deformations of this gene are present in humans (Waardenburg type 2, Tietz Syndrome), mice (microphthalmic), and hamsters (anophthalmic white). Mice also have associated deformities in Tfe-2 and Tfe-3, and there's an article somewhere (I don't have my bookmarks on this computer) where differently broken copies of Mitf are combined, and they tend to result in animals showing the traits of the "least broken" variant they have. So I am dubious of your claim that roan x dal doesn't produce lethals since, as you claim, they are merely different broken alleles of the same gene. Also are you quite positive that dal x dal produces strictly anophthalmic offspring? Any lethal white offspring of a dal with eyes would disprove this.

I'm not arguing that on paper 1:4 could be "lethals", cause on paper thats true, but you could still get a whole litter of them, or none at all born.

Yes, that's what I said! You have a 1 in 256 chance, in a litter of 4, of having them all be lethals, and a 81/256 chance of none of them being lethals. You do know what a 25% probability is, right?

[Matt & Guins]

Originally Posted by salana

I googled for your sources but was unable to find any mention of them, except one site said a MSN group had the "Color Genetics in Cavies" as a file, but I couldn't find it on their homepage.

Sorry, my mistake. Didnt have them next to me and made a minor error in the title.

Colour Inheritance in Small Livestock (not mammals). Roy Robinson is an actual geneticist - very interesting reading.

Color Genetics in Cavies - should be "the cavy" not cavies.

[The Magic Taco]

what are lethals?

[Matt & Guins]

Originally Posted by The Magic Taco

what are lethals?

I'm sorry for souding rude, but have you even bothered to read this post right from the start? If so, i'm sure you wouldnt find a need to ask such a question.

Matt