# Controlled Atmosphere Killing



## PulpFaction (Jul 23, 2009)

Has anyone ever used, or even heard of this method?

Someone on the ColonyRaisingRabbits posted it yesterday and I consider it basically revolutionary to my rabbit operation.

As some background, I have no problem with killing animals for a justifiable reason, regardless of what that may be. I've euthanized my fair share and assisted in the process on many more animals as a vet tech. A quiet, painless death slipping into sleep is something that is easy for me to face.

Where I have problems is relying on my own strength and skill to kill an animal that is being unnaturally handled, which is what seems (to me) to be going on with every other method of dispatching meat rabbits I have researched.

Anyway, I reposted the tutorial here: http://homelesshomesteader.wordpres...atmosphere-killing-for-meat-rabbits/#more-408

Like I said, it's a game changer as far as I'm concerned.


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## SFM in KY (May 11, 2002)

Interesting. I've also read something somewhere about using helium (which you can get in tanks at party supply stores for blowing up balloons) in the same way. I'll try to find the original article, but apparantly it is very quick and also does not leave any residue in the meat.


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## Truckinguy (Mar 8, 2008)

Very interesting. If it's as easy as it sounds and they just "go to sleep" I would be interested in that. It might be an additional selling point to some people that the rabbit had a peaceful and non violent death.

I wonder how long you would leave them in the container to make sure they're gone. I'd hate to have one wake up as I was starting to skin it!


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## PulpFaction (Jul 23, 2009)

Truckinguy said:


> Very interesting. If it's as easy as it sounds and they just "go to sleep" I would be interested in that. It might be an additional selling point to some people that the rabbit had a peaceful and non violent death.
> 
> I wonder how long you would leave them in the container to make sure they're gone. I'd hate to have one wake up as I was starting to skin it!


Even if they weren't completely dead, only unconscious, you immediately pull them out of the box, take the head off and bleed them out. 

Anyway, I went back and re-read my post because in the original the guy said it should take from 5-20 minutes and realized there were several important paragraphs missing from the end of my post. 

I corrected that and now have it posted in its entirety. Sorry 'bout that.


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## Madame (Jan 1, 2003)

Sounds like an easy death - what we all want for our critters.


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## preprunner (Jun 6, 2009)

FWIW, I've been using this method to kill my feeder rats and mice for over a year. It is extremely simple to set up and get going. I can take a picture for those interested, but you'll find plenty of pictures online if you search "co2 rats, rodents, etc." This is the way all the big rodent suppliers kill there animals. 

My setup consists of a tupperware container (the kind with latching lids) with holes drilled in the lid, a couple hose clamps, some clear poly tubing from HD, and a 20lb co2 tank. I've used that 20lb tank for almost a year and it's still 1/3 full or so. Whole setup including buying a 20lb tank was about $100, give or take $20.

As far as the process, I've read that it's not economical on a big scale with rabbits, and they're likely to injure themselves by jumping up during the gassing process. I can tell you first hand the animals don't just peacefully go from walking around to taking a nap. The minute they smell/feel the gas (it chills as it expands) they start going a little nuts. A few seconds later they'll start breathing really heavy while stopping moving. After about a minute they're pretty much passed out not breathing. You'll see the oddball still take a breath passed out. That's when I flood the chamber with a big hit of gas and let it sit for 5 minutes or so. Then they're good to go.

I can't attest to the butchering process post-gasing as I've only done it with rodents. The only difference is that the animals look really pale.

Dunno if that helps anyone. I still broomstick my rabbits because I feel like it's over MUCH quicker. IMO, they go from sitting on the floor, to a stick over there neck in an uncomfortable but not painful way, to dead, in about 5 seconds. Much quicker. And sense I'm going to butcher them anyway (a messy process), I'm not trying to preserve there body state (like I would for a feeder rat). So I chose not to do it for the rabbits.

Hope that helps someone.
Jeff


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## RiverPines (Dec 12, 2006)

IMO, the cost just doesnt make sense when a box of pellets for the pellet gun is cheap and one shot to the head and they never know what hit them.
No panic or stress being put in a strange container. No strange feeling as the CO2 starts to make them feel funny.
CO2 just isnt cost effective and IMO not better than a gun.

With a gun I give them a treat and as they calmly and cluelessly nibble away, boom, over.

We try to do everything painless but if its fast enough and to the right place, brain....theres no pain, instant brain dead. The stress of some of these painless methods, IMO, isnt fun either for the animal. They get scared when put in some strange container. They want out.

But nibbling on a treat in familiar areas, no stress, no worries.


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## Pony (Jan 6, 2003)

For us, it's easiest to use the air pistol. Scritch between the ears on regular basis so that they don't even flinch when you put the barrel on their heads, and then ... it's done.

Don't need to worry about whether tanks are full or CO2 is available, don't have to close the rabbit up in an unfamiliar place, really fast and painless.

But that's me.


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## Guest (Jun 8, 2010)

As far as quickness and cost-effective, a blow to the back of the head requires no equiment or bullets. It's instant.


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## Ceres Hil (Aug 13, 2008)

what about the rabbit wringer? any thoughts on this?


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## byexample (Aug 28, 2009)

For whatever reason, the whole idea of setting up a gas chamber for doing in rabbits kinda creeps me out... way more than any of the other popular methods for dispatching rabbits prior to butchering.

As Lyndseyrk said, a blow to the back of the head is both quick and cost-effective.


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## lisa's garden (Apr 1, 2010)

I realize that whacking your rabbit in the back of the head is tough. But I can do it, because I choose to raise meat for my family. I hope that by the end of this year I will be able to raise enough that I can completely boycott the factory farms. That is what I remind myself of when I pull out the ol' hatchet.


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## cowbelle (Mar 5, 2009)

Along the same line, but I think simpler, is just to purchase the large brick of dry ice at the grocery store. We put it in an old cooler, cover with a thin old towel and put the small animal in it. Takes just a few breaths, no sign of stress, just lie down and die. Inexpensive, easy, and it works. My grandson used it for various rodents for his snakes.


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## MaggieJ (Feb 6, 2006)

Everyone must find his or her own most comfortable method. There is no "best". As long as the chosen method is humane - fast and pain free - it is acceptable. 

Personally, I'm happy with the pellet gun. I won't bop or broomstick because I don't have the strength and co-ordination to be sure of doing a good job. Other people have no trouble with these methods. I took a long hard look at various methods before settling for the pellet gun, including CO2 and a rabbit guillotine, but in the end settled for what I felt most competent with. I come from a hunting family.

Discussion is good. It's always helpful to know several methods that work well, just in case your current method is unavailable.


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## Otter (Jan 15, 2008)

Sometimes, what's best for us is not what's best for the animal.
For example, when DH was younger he used to help his uncle butcher turkeys. They did it with a baseball bat.
Sounds horrible, right?
Think about it from the turkey's viewpoint.
No one picked them up and positioned them un naturally while they flailed, trying to get themselves upright. No flapping of wings, no stress on the joints. No being herded, chased, carried to someplace unfamiliar, not even so much as a break in the daily routine.

They went out, scattered some scratch and when the selected bird raised it's head, swung for the outfield. Aim just below the head. Instant cervical dislocation and death. Literally, never knew what hit them. 
But it _sounds_ just _awful_.

I've butchered rabbits different ways and now I just won't do it unless I can shoot them. I've watched people broomstick and I'd rather shoot. In an emergency, put it out of it's pain quick situation, I'll use a hammer. A really sharp hatchet for small birds and DH's uncle's method for any bird to big to be comfortably picked up.

It might SOUND bad, but all of those things are very quick, and they sometimes struggle with the CO2. I'd rather subject them to a heartbeat's worth of pain then a minute or two of stress.


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## Pony (Jan 6, 2003)

Lyndseyrk said:


> As far as quickness and cost-effective, a blow to the back of the head requires no equiment or bullets. It's instant.


I know some folks have mastered that method, but for whatever reason, I always bruise the meat pretty badly when I whack the back of the head.

So, it's pellet gun or jugular cut for me.


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## Caprice Acres (Mar 6, 2005)

I've euthed rodents with CO2 - except I made it using vinegar/baking soda - the gas that bubbles off is CO2. That would make it more cost efficient, and the smell doesn't seem to bother them... it is just the CO2 that really bothers them. Though, the stress level does rise with the smell and being in an odd container. However, they FREAK when they feel the CO2 working, so I'd argue that other methods are more humane. I've switched to cervical dislocation with my mice, and cervical dislocation with my small rats, head bopping for larger rats. 

With rabbits, I've done them several ways. One way that works is to have a dog choke chain hanging from a tree. I loop it choker style around their necks loosely, until I pull down very fast and very hard in one movement - so they're never choked, the idea is to break their necks very fast. This method works 'ok' because it also tends to dislocate their backs - though pulling on their shoulders works well too.

My favorite way to butcher is just a pellet gun. It's fast and very, very humane. I shoot, grab my knife, and start a bleed. I then hang by the back legs and remove the head. Works great for me.


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## Guest (Jun 9, 2010)

I'll add that my husband does the dispatching around here. He's twice the size of me. I don't think I'd have enough strength to do it properly to be instant...I'd probably go with a pellet gun if I had to do them myself.

Question: How does one put down a newborn (or still in the nestbox kit)? I've never had to do it. But pretty sure it will come into play one of these days...I read somewhere where someone tried to "broomstick" a newborn with a pencil...and pulled its head off in the process...


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## Pony (Jan 6, 2003)

Lyndseyrk said:


> Question: How does one put down a newborn (or still in the nestbox kit)? I've never had to do it. But pretty sure it will come into play one of these days...I read somewhere where someone tried to "broomstick" a newborn with a pencil...and pulled its head off in the process...


I don't know why it's harder for me to kill kits, but it really is.

Still, when it needs to be done, I twist their necks around very quickly.

Surprisingly easy, but there's still the "oooh...." factor.


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## RiverPines (Dec 12, 2006)

I put down kits and baby rats all the time for my snakes. I feed dead not live to my snakes. I just send the baby to the floor at 50MPH. They hit the concrete so hard, instant dead.
It may sound cruel but its an instantaneous death so very humane.


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## HendricksHearth (Jul 18, 2009)

The American Veterinary Medical Association notes that rabbits and other burrowing animals have prolonged survival times and physiological mechanisms for coping with the excess CO2 compared to other species. That means that they can take much longer to suffocate than say, a dog or chicken could.

Also, according to the AVMA guidelines for humane killing (http://www.avma.org/issues/animal_welfare/euthanasia.pdf), rabbits can not only experience the suffocation (even humans report CO2 as noxious at higher levels), but can also develop pulmonary and upper respiratory tract lesions before they die using CO2. This happens because carbon dioxide reacts with mucous membranes to dissolve the moisture from the body prior to unconsciousness, the product of which is carbonic acid. Sometimes during research, the rabbits would stand on their hind legs if given enough head room to try to breath the oxygen above them and some might look "peaceful" and still, but their distress can be measured after death through their blood chemistry (ACTH, glucose, cortisone, etc.). 

We all know they are good at hiding pain (which is ironically a built-in survival mechanism), so this is just something to consider. Using a compressed CO2 cylinder with a measured amount is much better than dry ice, but it seems like a headshot or even cervical dislocation would be a lot faster (instant) and there would be less chance for inadvertently causing the animals to suffer prior to death without the owner even knowing they are hurting.

Best of luck,

Lauren


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## pfaubush (Aug 17, 2009)

I'm with byexample. The idea of the gas chamber seems creepy. I've seen cervical dislocation done and heard the rabbits screams. No thank you. If a 250 lb. man can't do it correctly the first time, I certainly don't trust that I will. I don't trust myself with the bopping method either. I would worry that my reflexes would stop me before I bopped them hard enough and all I would do is cause pain. I don't own a pellet gun, but we do own a .22. This works fine for me and is instant. I put them in a cage on the ground with some greens, wait until they're content, and then pull the trigger.


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## PulpFaction (Jul 23, 2009)

Ok, how loud is a pellet gun? I live in downtown Anchorage and shooting a .22 is out of the question unless I want the cops showing up. I've never shot a pellet gun, but every other gun I've ever shot is not something I want to deal with in the city.

One of the major appealing points for me on this is that it's silent. That's REALLY important.


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## Pony (Jan 6, 2003)

PulpFaction said:


> Ok, how loud is a pellet gun? I live in downtown Anchorage and shooting a .22 is out of the question unless I want the cops showing up. I've never shot a pellet gun, but every other gun I've ever shot is not something I want to deal with in the city.
> 
> One of the major appealing points for me on this is that it's silent. That's REALLY important.


The pellet gun is very quiet indeed. It's not even half as loud as a firecracker.

I'd say it's less than half as loud as a slamming door. 

If Nick were to fire it inside at one end of the house, I would not hear 2 rooms away. (And I know this because he had to shoot a feral cat that broke into the house through an open window. The pellet gun didn't work, but the .22 was not very loud, either.)


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## MoonFire (Jun 1, 2010)

RiverPines said:


> IMO, the cost just doesnt make sense when a box of pellets for the pellet gun is cheap and one shot to the head and they never know what hit them.
> No panic or stress being put in a strange container. No strange feeling as the CO2 starts to make them feel funny.
> CO2 just isnt cost effective and IMO not better than a gun.
> 
> ...


this is how I dispatch mine. (pellet gun) I have never had any issues. even if there is some movement, you can check for an eye response. they are always just dead. I too was a vet tech for years, am certified in Euthanasia, have given the pink juice to many many critters over the years...and though some people feel pellet gun dispatching is violent...it is immediate...and if you are processing the rabbit anyway...well the pellet gun is not more violent than the butchering part. I agree, they wouldn't just sit and go to sleep...they might panic. and hurt them selves, pump all that nice adrenalin all through the meat...
interesting idea. always good to come up with new better ways to kill the food animals 
JS


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## MaggieJ (Feb 6, 2006)

Pellet guns are quiet. Not even as loud as clapping your hands hard. It's more of a cough than a bang. The neighbours would never notice it... especially if you had a radio on.


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## PulpFaction (Jul 23, 2009)

HendricksHearth said:


> The American Veterinary Medical Association notes that rabbits and other burrowing animals have prolonged survival times and physiological mechanisms for coping with the excess CO2 compared to other species. That means that they can take much longer to suffocate than say, a dog or chicken could.
> 
> Also, according to the AVMA guidelines for humane killing (http://www.avma.org/issues/animal_welfare/euthanasia.pdf), rabbits can not only experience the suffocation (even humans report CO2 as noxious at higher levels), but can also develop pulmonary and upper respiratory tract lesions before they die using CO2. This happens because carbon dioxide reacts with mucous membranes to dissolve the moisture from the body prior to unconsciousness, the product of which is carbonic acid. Sometimes during research, the rabbits would stand on their hind legs if given enough head room to try to breath the oxygen above them and some might look "peaceful" and still, but their distress can be measured after death through their blood chemistry (ACTH, glucose, cortisone, etc.).
> 
> ...


I did notice this, but I also noticed that the AVMA says SOME species of rabbits and other mammals, so I wonder if that applies to domestic rabbits that have long been bred and raised above ground. Even then, it should only take a slightly higher concentration of the gas to cause unconsciousness, and then a bit longer in the chamber for death. 

Other research I have found also notes that analgesic effects should be achieved with a low saturation of CO2 (30%-40%) before going to a higher saturation, because it is the high saturation (>80%) that causes the painful side affects to a conscious animal. These are the kinds of things that might be witnessed using dry ice or a shoddy set-up that doesn't control the saturation levels well.

I also noticed that under the same AVMA guidelines it says that both cervical dislocation and stunning of anything bigger than a rat is either an unacceptable method or acceptable only with scientific justification--and only then with someone that is very skilled at the process. I guess eating would be justification enough, but still...I'm not comfortable with the mishaps that may occur while trying to obtain that skill level.

As for cost...the OP I got the info from says he can euth over 100 rabbits for about $20.00 with his set-up which avoids wasting the gas. I can handle that cost. He has the valve for control, and a box with little head room to prevent prolonging the process anymore than necessary.


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## MoonFire (Jun 1, 2010)

PulpFaction said:


> I also noticed that under the same AVMA guidelines it says that both cervical dislocation and stunning of anything bigger than a rat is either an unacceptable method or acceptable only with scientific justification--and only then with someone that is very skilled at the process. I guess eating would be justification enough, but still...I'm not comfortable with the mishaps that may occur while trying to obtain that skill level.


I totally understand that. that was actually my reason for using a pellet gun. I thought, I am used to needles, lol that is NO WAY I am thumping this poor thing in the head ir chancing NOT breaking the neck the first time and in the right place!! omg that would be horrible. I am curious to hear more about this as you research it. but so far so good for me. I haven't had even one so far that went wrong...I just keep picturing the rabbits having a reaction like a ketamine cat waking up! that always made me feel so bad, until other drugs came online... thanks for sharing good topic!!

JS


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## prairiedog (Jan 18, 2007)

I favor the pellet gun too they are gone so fast they don't have time to react


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## Immaculate Sublimity (Apr 30, 2003)

Ok I have to ask... after the pig fiasco with shooting something in the head I'm not real inclined to try it again without detailed directions. do you hold the rabbit still and put the pellet gun (rifle? pistol?) against their heads? do you leave them in a cage and aim through the bars while they're munching away from a few feet or inches? shoot them from behind? or infront? or straight down? Like I said the pig thing was almost enough to make me consider never trying this alone again. so DETAILS would be muchly appreciated.


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## Pony (Jan 6, 2003)

I understand your concern. We had an unnerving experience shooting an animal, too, so I now share with you <drum roll>

_*PonyDetails<tm> for Rabbit Shooting:
*_

Make sure that all tools are in place.

1.) pellet gun: loaded, pumped, cocked
2.) very very very sharp knife

Bring rabbit out of cage. Carry to a nice, grassy spot where your tools are waiting (I take mine over by the feed bins, where I have set the gun and knife).

Place rabbit on the ground, holding firmly so that it cannot get loose. 

Take the gun and put the barrel between the rabbit's ears.

Fire the gun.

Take the very etc sharp knife and slit the rabbit's throat to cut through the jugular vein. Repeat on the other side.

Pick up rabbit by back feet and let hang upside down while it bleeds out.

Rabbit is done bleeding out when its tail droops. (Yeah, it's weird, but that's how Nick and I call it.)

We then put the rabbit into a five gallon bucket of water, and then dispatch 3 more rabbits. The water wets the fur down so it doesn't go flying all over the place when you dress it out.


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## pfaubush (Aug 17, 2009)

Huh, I never thought of wetting them first. I hate the flying fur!!! Does the temp difference make them any harder to skin? I've heard they're easiest when warm.


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## Pony (Jan 6, 2003)

pfaubush said:


> Huh, I never thought of wetting them first. I hate the flying fur!!! Does the temp difference make them any harder to skin? I've heard they're easiest when warm.


I never noticed a difference in temperature, but Nick and I work pretty fast when we're skinning/dressing out. We do four at a time (he does two and I do two), and have those done inside 30 minutes.


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## a7736100 (Jun 4, 2009)

I suggest you cut open a rabbit head down the middle from front to back. Look at the brain. Try to position you gun so the pellet will go through the most brain.

If you do it in the basement away from nosy neighbors, you can put the rabbit in a metal wash tub. My rabbits usually stay still long enough for me to shoot. The tub is easier to wash than the floor.


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## Immaculate Sublimity (Apr 30, 2003)

I assume then a pistol type pellet gun? I have a rifle type.


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## Caprice Acres (Mar 6, 2005)

I use the rifle type pellet gun - works fine. 

As for making the shot, I have a show carrier that holds 4 fryer age. I take off the pan and since the floor is attached, they can't get loose. The lid has 2"x1" mesh, so I poke the barrel through the hole to whichever one is staring at soomething, then fire right between the ears. They're dead ASAP. I make sure to keep the lid unlatched so I can quickly grab said bunny, slit throat, and hold up, all while keeping a foot on the top to the carrier so others don't escape. Then I make cuts between the achilles and leg bone and hang from the tree which I butcher at... Making sure to latch the carrier until the next bunny. 

After butchering I simply scrub down the cage, which I also use to take bunnies to show, farmer's market, etc.


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## MaggieJ (Feb 6, 2006)

Methods using a pellet gun vary. I prefer to put the rabbit in a cardboard box with something yummy to nibble. If I have a helper, I get him to gently push the rabbits ears forward so I can easily see the back of the neck. I put the muzzle of the gun right against the neck, just below the skull and fire at point blank range. A hand-gun style pellet gun would make this very easy for one person to do.


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## thaiblue12 (Feb 14, 2007)

I have not used Co2 but I have used dry ice. I am far too much of a sissy to use a gun, or a knife. My last ferret who was sick and needed to be put down went with dry ice. The vet says they can only stick the needle in their heart, they sometimes miss and charge you $75 for it. For $5 I got a chunk of ice, pet him well, tossed some treats in and he was gone before he could finish them. 

Probably not a cheap as bullets but if you are a squeamish you can probably get quite a few rabbits done with one block of ice. Do not put it in your freezer and wait till the next day however, it will be gone... yea I did that lol.
It is the fumes that kills them not the actual ice so make sure somethign is in between the rabbits and the ice or you will have bunnyciles


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## rabbithappy (Jun 24, 2009)

Do they thrash around, freak out, & act like they are suffering though as was mentioned with the CO2 tank? If not, I might actually consider trying this once. I have a good pellet gun & have used it with success, but I am so tender hearted that i can barely stand to do it, even though its instant. I think it would be easier if I hadn't raised the bunnies myself. But I must admit, I enjoy spoiling them, petting them, etc, so that by the time they are ready to butcher, they are so dang friendly, they mob the cage trying to see who can get petted first! After that, I can't bear to put a gun to their heads & end up selling them instead. All the while, wishing I could have a nice dinner of fried rabbit! Maybe I just need to hire someone to dress them out for me, but then that just makes for a more expensive dinner. So let me know how the rabbit acts when it/they are in the container with the dry ice. Thanks!


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## jen74145 (Oct 31, 2006)

Mmm.

When I took my kitten to be neutered, the vet let me watch her knock him out. She did the storage tub with gas, largely because he was a bengal and they don't do well with injectable anesthesia.

Sweet, very tame, bottleraised and harness trained kitten. Totally used to people and being enclosed in carriers. He positively flipped his lid as he got drowsy, thrashing and panicking. She (vet) said it was very common for an animal to do such.

She topped him off with a tiny bit of injectable for the actual neuter, in case anyone's hair is on end, lol.


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## rabbitgeek (Mar 22, 2008)

Lyndseyrk said:


> Question: How does one put down a newborn (or still in the nestbox kit)? I've never had to do it. But pretty sure it will come into play one of these days...I read somewhere where someone tried to "broomstick" a newborn with a pencil...and pulled its head off in the process...


I take the little one and smack the back of the head sharply on a hard surface like a counter top or appliance. One hit stuns it senseless and probably kills it outright. Two hits makes sure. They never know what hit them. I usually put the little one in a plastic sandwich bag before I smack it to prevent little messes. Then I can wrap it up to put in the freezer for feeding to carnivores later.

As with other methods, there is some muscle reflex twitching, but the rabbit is dead.

Have a good day!


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## cowbelle (Mar 5, 2009)

My daughter has used the CO2 for snake feeding animals, and has observed carefully that they simply take a few breaths, and go to sleep. No trashing whatever. She uses an old cooler and the dry ice from the market. Pretty simple.


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## thaiblue12 (Feb 14, 2007)

rabbithappy said:


> Do they thrash around, freak out, & act like they are suffering though as was mentioned with the CO2 tank? If not, I might actually consider trying this once. I have a good pellet gun & have used it with success, but I am so tender hearted that i can barely stand to do it, even though its instant. I think it would be easier if I hadn't raised the bunnies myself. But I must admit, I enjoy spoiling them, petting them, etc, so that by the time they are ready to butcher, they are so dang friendly, they mob the cage trying to see who can get petted first! After that, I can't bear to put a gun to their heads & end up selling them instead. All the while, wishing I could have a nice dinner of fried rabbit! Maybe I just need to hire someone to dress them out for me, but then that just makes for a more expensive dinner. So let me know how the rabbit acts when it/they are in the container with the dry ice. Thanks!


My ferret did not freak at all. He ate some treats and went to sleep. I think some animals may freak about being put into a box, but ferrets like enclosed places and there was food involved. Just do not put them directly on the ice, have some type of barrier that they do not freeze to it but the gases can escape.


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