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This baby dragon was found dead still inside his egg on January 2nd, 2005. I thought this was a very interesting case and decided to post these photos here for the interest of others.

This hatchling had been able to slit its egg shell and get only his mouth and nose out before it expired. Upon discovery, the hatchling was removed from its egg for examination and to determine cause of death.

Note the following abnormalities:
1. tail is completely lacking
2. body and neck are markedly enlarged
3. left nostrol communicates with the mouth and there are no teeth on rostral (nose) end of the maxilla (upper jaw).
4. Both rear limbs are dysplasic (deformed), the left rear food has an extra digit (polydactyl) which is much larger than the rest of the digits on this limb.
5. The "cloaca" (or what looks like one here) does not appear to have a true opening to allow for defication.

"His" (sex could not be determined due to lack of cloaca) parents are a pair of Sandfire het Leucistics. No other offspring have shown any deformities, either in this clutch or older sibs. This is believed to be a fluke.

It is assumed that if this hatchling would have survived the hatching process it would have required euthanasia or eventually succomed due to lacking a true cloaca.

Ok I don't know why these aren't working when I am posting them according to what kingsnake.com says.

You can see them at the following link.

http://therasdragon.splunk.net/BDs/Deformed/deform.php
http://therasdragon.splunk.net/BDs/Deformed/deform.php

Bummer, but very interesting. I hope to see what others have to say about it. One thing I have in mind is, were the parents siblings/related? Considering that they are both the exact same morph and het for whatnot, then it leads me to think that they were purchased as a "pair" but were really siblings. Obviously it is a genetic defect. Just a thought

David - KDRKreatures
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KDRKreatures.com
Exotic Reptile Breeders - Specializing in Bearded Dragons

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This is a congenetal defect. What does congenetal defect mean? Means they were born with it. Thats ALL it means. It may or may not be genetic. You can be born/hatch with a defect and have it not be genetic at all. You can havea genetic defect and not have it show up until you're 50.

So how can you be born with something and not have it be genetic? Easy. Mistakes happen, A LOT. Think of Spina Bifida in humans. That's not genetic, but you're born with it. How does that happen? Not enough folic acid, drug use by parent, and sometimes it just happens because the baby just plain failed to grow correctly. Same with congenetal heart defects. Most congenetal defects aren't genetic at all.

Actually most genetic defects are subtle and do not result in deformities of this magnitude. IF a genetic defect did occur that WOULD result in something this drastic, the offspring would not have survived full term until hatching.

So how do you tell if a defect IS genetic or not? Statistics.
How many deformed offspring HAVE the parents produced?
The fact that they have produced ~70 offspring and had this happen ONCE would actually mean it is not genetic. If it were a genetic defect it would have been seen in higher frequency (~ 25% actually). 1/70 tells me not genetic.

The parents are distantly related and are not siblings.

So how come imbreeding is associated with birth defects? Well members of the same family line are MORE likely to have the same genes. But only MORE likely. For the most part siblings on average only have 25% of their genetic makeup in common. They can have as little as 0% and as much as 100% (as in twinning). Most though fall around 25%. Now, in the case of normal parents producing a deformed offspring, in order for it to be genetic it would HAVE to be a recessive trait. Now lets say the parents are full sibs, they have about a 25% chance of EACH animal carrying the defective gene. That means for BOTH to have it, that's 12.5% change. Not lets say that we win the lottery and both DO have this gene. Like any recessive trait, 25% of the offspring SHOULD show the trait then.
Now of course this requires that there actually BE a defective gene in this family. Most families don't have big scary defective genes that result in a deformity as drastic as this.

So if you get what I am getting at, chances are VERY slim that FULL SIBLINGS can cause a genetic defect if they breed.
So how about completely unrelated parents? Since we don't know how much their genetic makeup is the same, we can't predict the chance of a genetic defect. But since they're not related the chances of them HAVING the exact same genes are pretty slim. Thus statistically LESS likely to produce genetically defective offspring. Then again this depends a lot on the genetic diversity of the population and you get into population genetics.

Anyway, to avoid further boredom I'll summarize this. Not all defects are genetic. Imbreeding does NOT guarantee genetic defects, only slightly increases the likelihood.

Sorry, I can't help it but in undergrad my VERY favorite subjects were Genetics, Embryology and Principles of Animal Breeding. Truely fascinating things.

12.5% should actually be 6.25% because I was suppose to multiply 25% times 25%. Sorry. So even a LESS of a chance that both parents HAVE a defective gene.

NM I was right, 12.5% chance that BOTH parents have it.

LOL thanks for clearing that up for me Thera. We learn something everyday!

David - KDRKreatures
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David and Kevin

KDRKreatures.com
Exotic Reptile Breeders - Specializing in Bearded Dragons

Email

I just don't like this misconception that imbreeding = deformities. It doesn't. You can get completely deformed babies from parents who are completely unrelated.

I actually am thinking that I might write an article on this for posting on someone's page cos I DO think it's important for people in our hobby to understand. If you're breeding anything on any scale you should know about inbreeding (or linebreeding as most call it in the knowing) and what can cause deformities. After all, anyone producing lizards after a certain amount of time is BOUND to get a deformed baby. Wouldn't it be better if they could understand whether this is something to be worried about in future production or not?

I understand you took classes on this and all, and most likely that you understand this much more than I do. I was glad to learn. But (in my opinion) bearded dragon gene pools in the US are too shallow. There have been soo many inbreedings from inexperienced people, and those inbred dragons are thrown back into the bloodlines and bred with their sister or brother etc. It goes on. The thing is, there hasnt been new blood in the US besides the occasional European dragons being importing, so by inbreeding with the US BD's, it does cause many deformities in the dragons because of the severe lack of new blood. To get the new "phases" there WAS inbreeding,and to a certain extent it was alright. The bearded dragon bloodlines just cant handle any more of it, IMO. Of course there are many instances where, like this case, there is a deformity despite no inbreeding, just...deformities. They happen, even in humans. I was, in no way, accusing you of inbreeding, I was just saying my thoughts, and a possible solution to help you out.

Just wanted to clear that up. I enjoy learning from you, and please share more of your knowledge. I hope to be a herp vet, and everything you have been saying sounds really interesting.

Thanks

David and Kevin - KDRKreatures

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David and Kevin

KDRKreatures.com
Exotic Reptile Breeders - Specializing in Bearded Dragons

Email

...and captive gerbils in the US are all descended from the same 6 original imported animals.

Inbreeding is and always will be a risky practice. It is important to out-cross whenever possible to improve a blood line.

The phenomenon you speak of isn't about deformities at all, but loss of what is often referred to was "hybrid vigor". I don't know what your knowledge of genetics is, so if this is a repeat of information you already know, excuse me for it. Everyone has 2 copies of every gene. ONe from mom and one from dad. If the copies are exactly the same this is called homozygous. If they are different they are called heterozygous. The more genes an animal is heterozygous for the more "vigor" it has. No one really knows fully why. Animals who are EXTREMELY inbred, like Cheetas or Pandas or Great Danes and Boxers, have less heterozygous gene pairs and more homozygous gene pairs, because mom and dad were more "alike" being related.
Animals who ARE extremely inbred often are less reproductively productive and successful, have smaller numbers of offspring each breeding, and have skulls that are asymmetrical.

The point of outcrossing is to ADD in genes that aren't in your line to produce more heterzygousity (scary big words, ah!). This is what responcible breeders do. The add NEW genes into their lines, but while also breeding to maintain the trait they were breeding for in the first place.

Pretty much that is the method I would suspect any high end breeder uses. Reason why so my Leucistic hets exist out there even. No one crosses a leucistic with leucistic yet. They cross it with someone from another line, like Sandfire or red sandfire or snow, or hypo, or sunburst, or normal, or german giants. But then you need to produce a leucistic from those hets otherwise you can't keep track of that gene, so you breed two hets from different parents together. For instance, my sandfires are from two different sandfire lines, red and yellow. My plan is to take their leucistic children and breed them to a female completely and utterly unrelated to their parents what so ever and produce again, hets.

Anyway, irresponsible inbreeding is what it is inbreeding, often when done correctly it is referred to as linebreeding.

So what responsiblity does the average bearded dragon owner have? Buy from responsible breeders. Encourage GOOD breeding practices that way. Don't buy from people you know nothing about. If you need to, ask around. If no one knows who they are, ask questions of that breeder, see what they know. And most of all, don't buy "pairs" unless they aren't from the same parents.

Good explanation, I like that.

Sean
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Heart Mountain Herps

>>...and captive gerbils in the US are all descended from the same 6 original imported animals.
>>
>>Inbreeding is and always will be a risky practice. It is important to out-cross whenever possible to improve a blood line.
>>
>>The phenomenon you speak of isn't about deformities at all, but loss of what is often referred to was "hybrid vigor". I don't know what your knowledge of genetics is, so if this is a repeat of information you already know, excuse me for it. Everyone has 2 copies of every gene. ONe from mom and one from dad. If the copies are exactly the same this is called homozygous. If they are different they are called heterozygous. The more genes an animal is heterozygous for the more "vigor" it has. No one really knows fully why. Animals who are EXTREMELY inbred, like Cheetas or Pandas or Great Danes and Boxers, have less heterozygous gene pairs and more homozygous gene pairs, because mom and dad were more "alike" being related.
>>Animals who ARE extremely inbred often are less reproductively productive and successful, have smaller numbers of offspring each breeding, and have skulls that are asymmetrical.
>>
>>The point of outcrossing is to ADD in genes that aren't in your line to produce more heterzygousity (scary big words, ah!). This is what responcible breeders do. The add NEW genes into their lines, but while also breeding to maintain the trait they were breeding for in the first place.
>>
>>Pretty much that is the method I would suspect any high end breeder uses. Reason why so my Leucistic hets exist out there even. No one crosses a leucistic with leucistic yet. They cross it with someone from another line, like Sandfire or red sandfire or snow, or hypo, or sunburst, or normal, or german giants. But then you need to produce a leucistic from those hets otherwise you can't keep track of that gene, so you breed two hets from different parents together. For instance, my sandfires are from two different sandfire lines, red and yellow. My plan is to take their leucistic children and breed them to a female completely and utterly unrelated to their parents what so ever and produce again, hets.
>>
>>Anyway, irresponsible inbreeding is what it is inbreeding, often when done correctly it is referred to as linebreeding.
>>
>>So what responsiblity does the average bearded dragon owner have? Buy from responsible breeders. Encourage GOOD breeding practices that way. Don't buy from people you know nothing about. If you need to, ask around. If no one knows who they are, ask questions of that breeder, see what they know. And most of all, don't buy "pairs" unless they aren't from the same parents.
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David and Kevin

KDRKreatures.com
Exotic Reptile Breeders - Specializing in Bearded Dragons

Email

Genetic deffects can occur from two parents that don't carry a gene for said defect. it happens in the way the genetic codes are passed to the offspring... That's why you see one hypomelanistic baby pop up in a clutch of normal siblings of wich none are able to produce this trait other than the one that is homozygoues for said trait. It is genetic but only this silbing has the genetic defect.... It is the aBSENCE OF ONE PART OF THE GENETIC CODE THAT IS LOST DURING "CONCEPTION .... woops hit cap lock... In some cases there are several lost, jumbled or broken codes that can cause anomolies such as the one you produced in this clutch. It happens all the time .... and as I said in my other post this is the basis of Darwins Theory of Evolution.... natures way of producing a new look that helps a species survive better in it's surroundings. Some new looks last others don't.... this is called natural selection.... In the case of your hatchling I'd say it was a sad but normal thing to happen that could have happened in any bloodline from any breeder includeing completely traceable and completely unrelated mates.

How do you think that land lizards came to be? they all derived from the sea.... But overf time they devloped lungs... legs... abilties that enabled them to go catch food by land... Billions of years of evolution and all from single celled organisms... think about that...

Later,
Robert Wood
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Don't choose your friends by show,
feathers float but perils lay low!

Hmmm... I'm not going to say whether it's genetic or not, I have no idea. I also studied genetics extensively back in college, now it's been a few years but your math is off. You are already banking on that 25% of your offspring will not only cary but show a genetic defect (leucistic), 75% of the total clutch should cary the gene also. And that's if the genetic defect is simple recessive and just on 1 marker, others could show more often. Also, the 'leucistic' dragons haven't been around very long and you can probably trace both of yours back to the same original set that Kevin got a few years ago. I'm not coming down on you for this, we are all breeding out of those lines, just making a point that they are not totally unrelated. Actually most (99% ) of the dragons in the US are related on some level already. The original population was very small and without being able to get new bloodlines in from Australia a genetic bottleneck has been created. I do agree that with most things linebreeding usually isn't a big problem but the chances of deformities with dragons is much higher because they are already so close to their limit.

Sean
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Heart Mountain Herps

I never claimed that my dragons weren't related. They are cousins and share a common grandparent. Any line of dragons out there is related to each other. That's the drawback to this "line" and "phase" business.

New to lizards and know nothing about abnormalities just interested in what could have caused it if you have any idea? i love animals all sapes and sizes like learning new things.
kay

read the rest of the posts.

I really have no idea what the cause could have been. Normally if it's caused by incubation problems you'd seen multiple deformities amoung the entire cluth and other clutches in that incubator. I did not. More than likely this was just a poor baby whose body god confused on how to grow correctly and cells that were suppose to develop in one place didn't and so one. Embryology is a weird science in itself, you add in Pathology into that and it gets more confusing.

If you wanna talk about weird, my last week of school last semester in Systemic Veterinary Pathology we studied congenital defects. One was called a "globulous amorphous". It's when a fetus just plain gets it completely wrong and is just a ball of fur (or in the case of reptiles it would be scales) resembling the tribblies from star trek. No eyes, no ears, no head, just a ball. What causes this? Nothing really causes it, its just one of those weird things that just happens.

So how CAN you know what happened? You usually can't. That's just the way it is with congenital defects. Unless you see it commonly in that blood line, like a hepatic-portal shunt in tyo breed dogs, you really are going on nothing. (BTW even if you see something a lot in a line, it's not so much purely genetically inherited, but the CHANCE of it happening IS, again, embryology is confusing).

WOW! Now my head hurts. Very interesting information on genetics You guys really know your stuff.

Lance
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1 male bearded dragon named Lenny
1 femal bearded dragon named Jewels
1 male or female mali uro named Milo or molly (not sure anymore)

take tylenol, that's what I use around finals.

From what I understand, deformaties such as this one occur when the genetic codes are passed from the parents to the embryo... Sometimes they are either not complete or are sort of jumbled (in english...lol) to the point that the phetus is not able to form correctly. It isn't because of inbreeding in my opinion as there are no others suffering abnormalities according to what you've said... sometimes it just happens. It could be that the codes were not passed on effectively due top one parent or the others genetic pool is weak to an extent but I seriously doubt it.

This is alos how genetic morphs are produced. A mutation occurs due to miscoded or incomplete codes passed down and this mutation occurs during oh dangit what's the word..... can't remeber... anyway.... it has to do with a malfunction during the "conception" and the fact that the genetic codes are either lost, misinterpreted, or incomplete during this stage of developement... I'm wanting to say mitosis? probaly wrong but can't remeber.... If I still had my book I'd be able to give a more detailed and indepth description....

It is just natures way of evolving... this is also the basis of Darwins Theory of Evolution.

Later,
Robert Wood
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Don't choose your friends by show,
feathers float but perils lay low!

my head hurts too but it is really interesting. i love science but struggle when it comes to genetics. i would love to figure out what caused thing like. really interesting
Kay