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Thanks for everyone who responded. I don't think I got a response from anyone in the medical field per se so I may not have a definitive answer, but here's what I did get. Generally speaking, most said that it wouldn't matter one way or another if a victim of a poisonous bite had CD. There does seem to be some anecdotal info that some with CD have a more acute response to mosquito bites, but that's it. (My son is just the opposite: He doesn't get any kind of reaction to mosquito bites, but me? I don't have CD and I get welts and itch all over. Go figure.) 

To answer a few responders: My son never climbs alone. It's not only dangerous in that he could fall or otherwise get hurt, but our mountains are home to rattlesnakes, mountain lions, bears, and drug runners from across the border. (No political statement...just fact.) A buddy system is absolutely required. In fact we have walkie talkies to keep in communication with the boys and to allow them to get help sooner if necessary. And a "snake bite kit" is a thing of the past; the old cut and suck out the venom is no longer the acceptable way to deal with snake bites. 

Thanks especially to those who were good at pointing out the importance to let boys venture out on their own. Mothers rarely understand this and mostly worry. Dads, of course, get it. To our credit, we plan on having our son take a climbing course this summer. It'll help him be smart and maybe, MAYBE, make me feel a little better when he's on an adventure. 

That's the summary, but for those who want to read more, the responses minus names follow:

I'm not a doctor so I cannot specifically speak to your concern about a rattlesnake bite reaction.  It would seem to me, though, that having CD would not make a difference, particularly if your son's gut has healed on the GF diet.  If, in the process of getting medical attention for a snake bite, your son needed to be given food to help mitigate a reaction, then it would be good for him to make sure he has GF snacks with him (which I imagine he would have with him hiking anyway).

I am, however, a mom who has raised 3 sons past the 14 yo mark and into adulthood so I can understand your concern about your son scrambling up rocky slopes, perhaps in the vicinity of poisonous snakes!  My husband has also told me that "boys will be boys" and I long ago realized that I would never really get it.  Oh well... and, by the way, is there such a thing as an "overly concerned mother?"  I'm not sure... ;-)
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That's a great question, and I look forward to hearing what people have to say. I have talked with people who have various types of autoimmune issues, and most seem to think their bodies overreact to bug bites, such as mosquitos.  So, it is an interesting thought/question.
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I think a reaction to venom would likely be the same for someone with celiac or without it (the antibodies we form are pretty specific to gliadin, I believe). Give him good pointers about avoiding snakes, but your husband is right in that he needs to get out and do some activities. Life has risks and looking back, I wish I had taken a few more reasonable risks when I was younger. I think young men need some adventure like that too--it helps them mature into men. We women don't always get that, but your husband knows your son needs this. :) He's probably much safer out there with the rattlesnakes than he is with some teens these days! 
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I have had CD for 30 years and that is the first time in monitoring this listserve for 20 years and many, many other Celiac lists that I have seen that question posed – it is a very good question! 
 
I do not live in snake country however if I was to apply this to a similar condition that I have which is a severe allergy to bee stings from being stung too often when I was a kid, I did ask my doctor about this last summer.  While not directly related to my CD but my medical conditions in general (I have 4 autoimmune conditions) it was whether I should continue to carry an epipen with me. 
 
She said she did not think I needed to as the ambulance service carries lots of primary antidotes on board these days (which in snake country I know ambulances and rescue services carry snake antidotes too) and I really do not go that far off the grid (like climbing mountains).  In relation to my autoimmune conditions, she told me having a bee sting is an allergic type reaction (IgE) not an autoimmune reaction.  I would assume it is the same with a snake bite – as an antidote has to be given to reverse the reaction, and it can, like a bee sting, be a whole body reaction, involving all organs shutting down until the poison is removed.  However it does not involve the autoimmune system in general.
 
She said that having a reaction to a bee sting the hospital emergency doctors would be more worried about imminent issues such as breathing, kidneys etc and my asthma would be more of a concern than the auto immune conditions which are currently under treatment – keep in mind, unless your son eats gluten he really should not have a flare up and in Canada where I live 99.99% of drugs are listed as GF.  Drugs that are a liquid and injected such as IV’s or pain killers are inter muscular and do not go into the intestines, they are absorbed into the blood/muscles and these meds do not include gluten in their liquid form.  The majority of drugs used in an emergency treatment situation – such as a person with an allergy reaction or heart attack are injected – they do not try and have the patient swallow drugs in that condition.
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I can say that I've never heard of that being a concern -- and it's not something that I worry about, beyond the fact that you never want to get bitten by a poisonous snake.

For the most part people with CD are just normal people, except they can't eat gluten. Your son is MUCH more likely to be hurt by things that kids are normally hurt by, car accidents and so on.
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Be sure your son does not hike anywhere without a snake bite kit and that he knows how to use it. And it would be better if he did not hike alone.
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