Question on Vet techniques and drawing blood from Crotalids.

[ChurleR]

Hello, I'm new to this forum and I have a few questions on vet techniques for Crotalids. I'm working with an entomologist in my Bio department and he chose me because I seem to be one of the only people experienced with hots. I'm decent at tubing and getting snakes prepped for vet care but I really need to know where to draw blood from. Is it a matter of personal preference or not? I realize that usually blood is drawn from inbetween two ventral scales, and I know about the anatomical differences between viperids and elapids/colubrids (ie heart placement). I just don't know where to aim or what type of needle to use. Any input would be much appreciated, and rest assured I'm not going to attempt to draw blood from any snakes before I know exactly what I'm doing. I refuse to injure or kill a snake due to my lack of knowledge.

-Will

[cobraman]

I recommend that you PM or e-mail MrsTT, who is a vet tech with reptiles. She skillfully did a blood draw on my Golds Tree Cobra.

[ChurleR]

Ahh, good advice, I was actually trying to get her email from the snakegetter's website. I'm very interested in several projects of people on this forum. I've read BW's posts about the Claxton RR rescues and I'll be glad to help him out, I live only 30 minutes away. If I lived closer to Florida I'm sure I'd try to get involved with snakegetters. Anyway, thanks for the tip.

-Will

[MsTT]

Hi guys, kind of busy cleaning up hurricane mess, but my email is snakegetters a^t usa dot net. I have no net access at home, so if you really need the help, email me with SNAKEHELP(555)1212 as the subject line, replacing 555-1212 with your phone number.

Crotalid blood draws in adults are easy from the tail as the tail is very well vascularized in all Crotalus and most Sistrurus. Cardiocentesis is harder in some species than others, and it's not something I could really teach in a short Internet post. I could do it for you and show you how in person, which won't help if you are not near Central Florida.

Cardiocentesis in a cottonmouth is always HORRIBLE as they have teeny tiny hearts, and their tails aren't a great site either, so they are not my favorite patients! It seems to vary in rattlesnakes by species but in general all the terrestrial viperids are a pain in the *** to do heart sticks on because they have very small and highly mobile hearts.

I do heart sticks on most elapids conscious or lightly sedated because it's usually easy and quick, and does not appear to be painful. I usually do moderate sedation on rattlesnakes and total anesthesia on some other terrestrial viperids for heart sticks because they can (no kidding) voluntarily move their hearts around while you are trying to stick them, which could be a hazard to the animal. If you are inexperienced at it, I suggest isoflurane anesthesia and dorsal recumbency so you can visualize the heartbeat under a strong light.

A 23.5 gauge needle is generally a good choice, small enough to cause minimal damage and large enough not to lyse blood cells.

The needle should go in at a slight angle as you are aiming for the bottom pocket of the heart. Keep a very slight suction on the syringe and wait for the "flash" in the hub that tells you you are in the right place. Isolate and steady the heart between your thumb and fingers or it will move.

I like Diazepam 0.2 to 0.5 mg/kg as a sedative, and an open drop box isoflurane anesthesia technique for crotalids and for really unhappy, struggling elapids.

Email me if you need more info, but remember that I am living in a disaster zone at the moment and may not have access to either Net or phone in a timely manner.

[SCReptiles]

on which side of Atl do you live? if you are on the north, you are not to far from us. you can stop by our place next time our vet is there. we have never had trouble drawing from the under side of the tail.

[ChurleR]

SCReptiles - I'm about 3 hours south of Atl, so coming by to see the vet work would be kinda tough. Thanks for inviting me by though, I'll probably be at the Greenville SC herp show to meet alot of like-minded people.

MsTT - Unfortunately it looks like I'm going to be working with your least favorite patients for the most part... Cottonmouths all the way. I suppose I'll try tail draws since their hearts are so hard to aim for. I'll most definately send you an e-mail with more info.

Funny how I'm stuck directly inbetween two helpful folks ;).

[MsTT]

You can get a caudal stick on a decent sized cotton, but the smaller ones you may need to do cardiocentesis on. We've had the best luck with cotton blood draws in the vet clinic using the open drop box isoflurane technique. You get reliable anesthesia for long enough to do your cardiocentesis, and a short recovery period.

I'd attempt tail sticks first, then move to the more invasive procedure if necessary. If you do cardiocentesis don't forget to keep pressure on the heart area with your thumb or finger for at least 45 seconds to let the pericardium self-seal after withdrawing the needle.

Heh. Sorry you're stuck with the most difficult patients there. In terms of handling cottons are easy, but trying to get blood out of one sometimes makes you wonder if they are related to turnips.

[ChurleR]

I may just aim to take the larger Cottonmouths out of the field, afterall the Prof is looking for something related to age. I'll send you an e-mail within a day or so with more info, thanks for being so helpful.

[MsTT]

Open drop box technique is easy in the field. http://www.snakegetters.com/demo/vet/isobox.html

Might not even be necessary for caudal vein sticks on large cottons, just tube them and have at. I don't know as I would want to try cardiocentesis on a conscious cottonmouth because the target is so bloody small and mobile. It's hard enough to hit when the animal is completely unmoving. If the critter is wiggling and able to voluntarily jerk its heart around, I'd worry about damaging the pericardium.

It's easy to drop them into an iso box as per the photo tutorial on the site. A healthy adult cotton will rarely need resuscitating. Maybe a few puffs to blow off the iso when you're done drawing blood. You can intubate with a clean red rubber catheter tube and just use your own breath to gently blow offf the isoflurane in its lungs and start it breathing again. One sterile tube per customer, cottons sometimes have flukes and you don't want to be transferring those around.

[ChurleR]

I believe I'll start out with caudal sticks on larger specimens, and get a feel for the heart with my tubing hand during those draws. A broad range of individuals should give me a good idea of heart placement. The isoflourane box is a excellent item to have knowledge of. The snakegetters site article (probably written by you... ;)) suggests a small animal ventilator during the process, is that necessary with cottons or do you believe the catheter tube revival is enough?
Vet tech grounds are pretty new to me, even though I plan on becoming efficient in it (at least to an intermediate degree) over the next couple of years. Your experience is extremely helpful and very much appreciated.

[MsTT]

If you have a sick and debilitated patient that has to be under for a prolonged period, you had better be prepared to ventilate. A small animal ventilator is a good thing for those situations.

A healthy animal that is dropped in the iso box just until it loses righting reflex should not need prolonged ventilation, though you may want to blow off the iso with a few manual ventilations. It may also wake up on its own, fortunately gaining muscle tone and reflexes back from tail to head so you have plenty of warning. More articles on that subject on my site.

There's another article on how to manually ventilate a venomous snake without intubating, though it is not as effective as intubation. Basically the snake's head is put in a short tube, a rubber glove or a plastic bag is wrapped around the snake to make a seal, and you blow gently in the open end of the tube. If the glottis is closed this won't work, so if you get no dorsal rise you may need to move to intubation.

A cheap and easy method of intubation/ventilation in the field is a red rubber catheter tube and your own breath. Don't insert the tube very far down, just barely beyond the second hole is sufficient. And don't use too big a tube - too small is better than too big for this purpose. Blow GENTLY, with barely enough force to puff a ping pong ball a few inches across a smooth surface. Overinflating snakes is extremely unhealthy. Observe the normal dorsal rise when a conscious animal takes a breath, and don't "inflate" farther than that. Do watch for some degree of inflation however, you want to see something that mimics the normal respiration pattern. I give from 4 to 6 breaths per minute, pausing every so often to watch for normal respiration.

I find the heart by palpation on cottons. It's fairly high up. Start looking/feeling about 25-30% of the way down from the neck and move down to 40%. That's the general range you'll find it in. A nontoxic marker can be used on the ventral scales once you locate the heart to help you find it again if necessary.

The heart is poorly anchored and will move depending on the position the animal is held in. So if you are tailing the animal the heart will move up a bit, likewise if the head is elevated it will slide down a ways. One of the reasons that these guys don't do so good at climbing.