Iguana necropsy

[joeysgreen]

Hey everyone, for those interested I've finally uploaded some pic's from an iguana necropsy last month. The pic's are graphic, so pass this up if you're squeemish.

See in the general forum at www.edmontonreptiles.com. I couldn't figure out how to post a direct link. The post took me an hour to type up, otherwise I'd just post it again on this forum.

Hope this is interesting for ya'll,

Ian

[minnow]

Hi Ian,
I hope you don't mind. I copied and pasted your post and hopefully inserted the pics in the right place. It was such an interesting read but your link didn't take me right to it.
Carol

Posted: Sun Apr 09, 2006 12:59 pm Post subject: Here's the necropsy photos---warning graphic

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Unfortunately, my camera isn't very good, but I'll try to explain what I'm doing, and what you're seeing in each photo. Hope it proves interesting.

The glare in this picture makes it hard to see, but what looks like a grey snake tongue is actually an endotracheal tube inserted into the glottis of the cadaver.




In this picture, I am resecting the skin to explore the anatomy of the leg. My goal is to verify the positioning of my intraosseous catheters (a catheter into the bone marrow cavity).




Here, I"ve begun the same on the other knee, and you can see me injecting saline into the marrow cavity in the femur.




You may recall the post I had a while back where it was discovered that iguania and varanidae did in fact evolve with venom. I wanted to explore this. Perhaps the most difficult task done was the scrupulous dissection of the lower jaw, looking for evidence of a residual venom gland. At times it was like splitting paper. I did come across a slightly more vascular area of "gum" tissue, but chemical analysis would have been needed to clarify if venom was present. It certainly wasn't functional like what you'd find in a snake, heloderm, or varanid. The tissue, is actually on the flap I removed, in the background.



Here I am attempting to show you the large ventral abdomonal vein that surgeon's must avoid when entering the coleomic cavity.



This is one of a few pictures that show the coleomic contents rather well. I'll try to describe what you're seeing. On the left, the dark maroon, glistening organ is the liver. The pink, vascular tubules are small intestine, moving towards the stomach (behind the liver in the picture). The darker grey tubule below is the large intestine. The smaller, dark maroon, jalapenio shaped organ I havn't 100% identified. It looks like it may be a "splenopancreas" but it may just be a lymph aggregate (herpetile style lymph node). You can see one of the testicles however, it's the slightly pink, light coloured jelly bean in the central part of the picture. The kidneys arn't seen, and are deep in the pelvic canal.




Where the kidney can be found.




What happened in this picture? I've inflated the lungs through the endotracheal tube placed in the first picture. You can see the two large, pink lungs take up a large amount of space where they weren't even apparent before. This is because, unlike us, the lungs are essentially, a balloon. Also of note, there was no diaphram to cut through. So when your iguana, or snake, or whatever herptile breathes in, the lung expanse extends deep into the belly. I hope this visually gives you the picture of why pneumonia is so difficult to treat in reptiles and why "common" upper respiratory infections should never be ignored.




Finally, for fun, I erected the hemipenes (only one shown) with saline. While this is a possible method of sexing live animals, there is a small risk of tissue damage that isn't there with other methods.

[kaley]

Very Cool! I've always been interested in seeing stuff like that...but unfortunatley the anatomy class that I did was just for livestock, dogs and a little cat stuff.

If you ever have turt pics, I'd be very interested! I thought about opening up the turt I had die here a while ago, but I just couldn't do it 'cause I felt so bad that he'd died...

Anyways, thanks for sharing!

Kaley

[Ryan Wunsch]

I'm glad Minnow posted it here, I can't see the ERAS forum for some reason.

You may recall the post I had a while back where it was discovered that iguania and varanidae did in fact evolve with venom.

I'd be interested in reading that if you would want to post it. I remember reading something on a varanid forum about it a while ago.

What happened in this picture? I've inflated the lungs through the endotracheal tube placed in the first picture. You can see the two large, pink lungs take up a large amount of space where they weren't even apparent before. This is because, unlike us, the lungs are essentially, a balloon. Also of note, there was no diaphram to cut through. So when your iguana, or snake, or whatever herptile breathes in, the lung expanse extends deep into the belly.

I never knew that, or ever gave it any thought. Without a diaphram, how do control the expanse of the lungs? When a bullsnake hisses, you can see the whole body expand - do they use their whole body cavity kind of like how a mammals diaphram functions?

Finally, for fun, I erected the hemipenes (only one shown) with saline. While this is a possible method of sexing live animals, there is a small risk of tissue damage that isn't there with other methods.

LOL @ for fun. Have you ever disected a monitor lizard? Just the other day I was talking to a person who had imported some rare monitors, and he thought them to be all males. I asked him why he thought that, and he said "they are all hung like a horse". From my understanding, that isn't an indication of the sex of a varanid. Frank Retes told me that female monitors have "hemi clitori" (or what ever the plural form of clitoris is), as large as the males hemipenes. I had seen our "female" argus evert and was quite concerned and thought that might have meant she was a male, until Frank told me otherwise. I think he sexes based on body shape of adult animals (he's developed quite the eye for it over the years)

I really enjoyed your post, feel free to make more like it. There is so much that is not known about reptiles. There is a theory that some people have, that monitor lizards somehow become males or females after hatching (I think somebody said that is impossible). Apparently, related or unrelated, if you grow monitor lizards together in groups from hatching, 9/10 the group will be sexed as 1.3, or 2.5 when they are able to be sexed.

That theory, combined with the hemiclitori being the same size as hemipenes - makes me think that maybe something previously unheard of is going on with the varanid lizards. Maybe they are all hermaphrodites, and they decide who is gonna be momma and poppa based on whatever factors would be most beneficial.

Ryan

[Ryan]

Very interesting Ian!! Thanks for sharing that with us.

[joeysgreen]

Thanks minnow, it made it so much easier to share

Ryan, some answers,
1) Dr. Fry has one of the best jobs in the world. All he does is chase animals and study venom. His site, venomdoc.com posts all his papers, if you'd like to search for more detail. Here's the short of it.
At first, it was thought that heloderms and snakes evolved venom separately. Dr. Fry recently discovered venom glands in both varanidae and iguania. Essentially the same venom as snakes. Specifically, pogonna (barbata?) and lace monitors (he's since done many more species) have been researched. Varanids actually have well formed, en capsuled glands just like a snake, but on the lower jaw. Lacking fangs, the venom exits at the base of the tooth and may be an explanation as to why monitor bites sting more and bleed longer. (and why Komodo bites'll kill you in a few hours, that bacteria justed didn't fit the picture). Iguanids, not really needing venom for the veggies and bugs they eat, didn't really evolve much of a gland, and it remains as more of a spongy tissue, albeit still producing small amounts of venom. This knowledge greatly increases the number of venomous reptiles, yet doesn't change the fact results of a bite. Our pets are no more dangerous now as they were last year

2) Yup. If you recall in high school biology, you were taught that people use the diaphragm OR their abdominal muscles. Play with your belly and see what I mean. Herp's just use their skeletal muscles and breathing is a conscious undertaking (however habitual it may become). This explains why while under anesthesia, they will stop breathing, while a person will not.

3) That FR is quite the character eh? Yes, varanids complicate things more then some would like. I don't have enough experience to say with certainty, but for most species I do believe that the clitoris is smaller, and if not, it does look different. From what I hear, mistakes are commonplace however. The easiest way that I know of to sex monitors, is to wait for eggs ... Seriously though, and with more difficulty, X-rays can sometimes be detailed enough to visualize a male specific genital bone, and if not, ultrasound should be able to do the trick. Finding a sonographer experienced enough to tell male from female monitors is a different story! As for them changing sex after hatching, while I wouldn't jump to that conclusion, it ain't impossible. That sex changing frog story in Jurassic Park is based on fact!

Thanks for the praise everyone and I'm just glad to contribute

Ian

[Ryan Wunsch]

Ryan, some answers,
1) Dr. Fry has one of the best jobs in the world. All he does is chase animals and study venom. His site, venomdoc.com posts all his papers, if you'd like to search for more detail. Here's the short of it.

I haven't checked his site in a while, thanks for the reminder!

He Joined a Canadian forum a while ago, and actually really liked some of the ideas that us Canadians had. I should invite him to join the HISS forum, we used to email each other about ideas, he's a really nice and down to earth guy (for being on T.V so many times) and has a great sense of humour.

He wanted to come to one of the snake counts a few years back, which was right close to the time of IHS or some event in the U.S he was speaking at. That would have been really cool if he could have made it, he hadn't been to North America in a quite a while before that I beleive, but things didn't work out for a trip to Saskatchewan for him.

....Lacking fangs, the venom exits at the base of the tooth and may be an explanation as to why monitor bites sting more and bleed longer. (and why Komodo bites'll kill you in a few hours, that bacteria justed didn't fit the picture).

I always wondered what kind of bacteria could kill prey so quickly from a komodo bite. I will have to make some time to read his new papers.

Anaconda bites also hurt and bleed more than other snake bites (speaking from personal experience) and I have read that there is an anti-coagulant in their saliva. I wonder if the good Dr. has ever looked into Anacondas.

Our pets are no more dangerous now as they were last year

By chance were you on that Canadian forum when Dr. Frye joined? This aspect was discussed a lot about the new colubrid studies.

That FR is quite the character eh?

Are you going for the understatement of the year award? I like him, not everyone does, but he is special in his own way. He seemed very nice on the phone, Shawn Fraser has met him and said he's really very nice in person too - but sometimes the way he types makes people wonder...

....I do believe that the clitoris is smaller, and if not, it does look different.

I"ve never had a chance to study them closely for very long, but the saline injection might be a way to sex monitors some day.

Seriously though, and with more difficulty, X-rays can sometimes be detailed enough to visualize a male specific genital bone, and if not, ultrasound should be able to do the trick.

I did not know males had a specific genital bone. I beleive in Europe they do use ultrasounds to help determine the sex.

A few years back when DNA sexing for birds was made available, I inquired about doing the same for reptiles. I think they said that it would be costly to set up a test, and nothing at that time was being done. Have you heard anything about that?

I've also wondered why the big name ball python breeders have not paid to develop the tests for genetic mapping, so that they could test their snakes to determine which ones were heterozygous for expensive traits. Perhaps it would be hugely expensive, but so are some morphs of ball pythons, and I have to wonder if it wouldn't be worth it for them to do that.

As for them changing sex after hatching, while I wouldn't jump to that conclusion, it ain't impossible. That sex changing frog story in Jurassic Park is based on fact!

I can't remember exactly what was said, but the person who said it was "impossible" made reference to something about sex not able to change after they are out of the egg (vs. temperature sexed leopard geckos).

But I've always thought science should never say "it's impossible" and study things that might be new and amazing. Please tell me more about the facts that the Jurassic Park is based on, I'd love to hear more on that subject.

The monitor theory interests me a lot and I'd love to know that somebody was studying that. Perhaps the right person hasn't heard the theory from hobbiests, and doesn't know that it is worth while studying. I've always thought that hobbiests and Universities should share more information with each other.

I wish I'd have taken Animal Sciences or Veteranary Medicine, but I'm very happy to have so many people that have / are on this list to discuss things like this with.

Very interesting stuff Ian, thanks again, keep it coming!

Edited to add: I started a thread to continue the discussion pertaining to Varanids sex being determined after hatching.
hisscanada.proboards98.com/index.cgi?action=display&board=theories&thread=1144793698

Ryan

[vanderkm]

Great post Ian - nice to see pics like these.

Have to agree Frank Retes is wonderful - I have not much interest in monitors but have learned so much from his approach to observation and understanding of snakes. I think the man is brilliant and just annoying enough to be interesting. Am trying out a bunch of ideas from him now with corns.

mary v.