A depressing subject to be sure. But anyway, do they really “Put the animal to sleep” with something before they do them in?
I’ve seen photos where a woman was blatantly tossing puppies into a vacuum chamber. Tossing. Say it ain’t so!
But, how do they do the deed?
Generally, a single injection both sedates and terminates the animal.
There seems to be some conflict about whether death-by-vacuum-chamber is cruel or not. I don’t believe shelter animals in the US are euthanized by vacuum chamber anymore. However, chickens destined for your dinner plate are.
I would guess that being rapidly decompressed to a hard vacuum would be unpleasant, as trapped air in your body (e.g. in your ears, sinuses, tooth fillings, and GI tract) may suddenly expand to painful volumes before it can be expelled. OTOH, military pilots are routinely subjected to simulated aircraft decompression events, in which the chamber is rapidly evacuated to a pressure consistent with cruising altitude (20,000-40,000 feet). Prolonged exposure to such low pressures first results in inebriation/stupefaction, then unconsciousness, and eventually death. For decompression to pressures consistent with very high altitudes (e.g. 50,000 feet), unconsciousness typically occurs in less than ten seconds (cite). This isn’t enough time for decompression sickness (caused by blood-borne dissolved nitrogen coming out of solution within the body) to occur. So it seems to me that a vacuum chamber that decreases its pressure very slowly to a very low level could be humane.
A 100% nitrogen atmosphere results in a rather quick death without the feeling of suffocation, that would certainly be a lot more humane than a vacuum chamber. 
The Wikipedia article for Nitrogen asphyxiation mentions burrowing animals do sense the lack of oxygen in this situation.
When I euthanized a pet several years ago, the vet came to the house and gave an injection. It really made me understand the euphemism “put to sleep,” because it was for all the world like he just lay down and went to sleep. It was remarkably quick and quiet. Except for the sounds I was making, of course, but that’s a different story.
When they put Haplo to sleep they gave him one shot to make him relax, then came back a few minutes later and gave him the other shot. The “relax” shot had him still aware and doggy, but floppy, and we held him. The “other” shot really was like going to sleep, and he was gone in seconds. It seemed, at least from the outside, very humane.
ETA - Yeah, Knead[, except for the sounds the people made.
I’ve had three dogs euthanized over the course of my life. All three times, it was one injection and looked like the animal was going to sleep, until the breathing finally stopped.
It was unnerving to still feel the muscles twitching on the first one as we took her home to bury her. She twitched the whole way.
The third one gave us quite a shock when she took a gasping breath 10 minutes after the vet declared her dead. He was still in the room and very quickly assured us it was a reflex action. Sure didn’t look like one.
Edit: upon reflection, it might have been two injections. One to relax, then the next.
What I don’t get about it is a barbituate overdose in humans can take a few hours to actually kill, which is one reason that it wasn’t in the initial lethal injection plan. Is it possible that some animals are technically living for a bit after being put down?
Is “euthanasia” a correct term if you are talking about killing healthy animals?
Off-topic but strangely not quite off-topic:
See, this is what I don’t get about the the brouhaha over whether lethal injection (for executions) is humane or not. Why is it so hard to develop a one-shot (or two-shot) way to put a human down just like with critters? If the current methods are so controversial, why is it so hard to develop a clearly fast and painless way, if we can do our dogs that way?
Is it a problem of the size of the critter – that is, humans being so much larger than doggies? Would it work with a horse?
A sad topic. In India stray dogs (of which there are many millions) are electrocuted. Its cruel and barbaric which is discontent for a nation of kind decent people. On the other hand cows wander freely but uncared for and there are organisations which look out for them.
I’m trying to look up an online (non-pdf) version of the AVMA euthanasia guidelines. I think I’ve linked to it before, but since they redid their website, now it is all fancy and hard for me to follow. I can get the 2007 guidelines, but not the ones with the updated content.
Now, the OP is talking about a situation in shelter animals vs a private animal euthanasia. In that case, yes it differs, and gas chamber (with carbon monoxide) is (in many places) an acceptable method for euthanising large numbers of animals. Even for that method, though, the AVMA guidelines propose specific procedures. I have not seen the updated version to see the changes made.
That is not, obviously, the same thing that happens when 22-year-old Fluffy the Maltese menace is euthanized at his house by his vet, with his owners nearby because of terminal disease.
Depends on the barbiturate use, some are fast acting and some are longer acting. I’m not sure how the metabolism of some were in humans compared to smaller animals.
The veterinarians are usually there when euthanizing the animal with barbiturates and check the heart rate, respiration, and deep pain reflexes (or lack of them) before declaring the animal has died.
Are there times where the animal is not killed by barbiturates? Probably, but this is rare. And heck, saying someone is “dead”, only to have him/her come “alive” later is not unheard either in human medicine.
And yes, horses are also euthanized by barbiturates. I’m not exactly sure about the doses, but given they are horses, it wouldn’t surprise me if they are injected with shots containing 20-60 mLs of euthanasia solution.
I was present for the euthasia of one of my gf’s horses. I watched closely, curious how it would work. She put an IV catheter into his jugular vein and attached tubing. Her assistant handed her a 60 ml syringe which was swiftly injected, then replaced with a second 60 ml syringe which was also quickly injected.
As she finished the second injection, the horse dropped like a ton of bricks. I was holding the lead rope. She warned me not to attempt to slow the horse’s fall, or I’d have nasty rope burns.
An excavator dug a hole, slid the horse in, refilled the hole, all in under an hour.
About 15 years ago, around here the regular method of euthanizing shelter animals was a pistol shot to the back of the head. Enough people were appalled that the legislature passed a law mandating lethal injection.
To corroborate kayaker’s story, typical doses for adult horses are in the 80-120 mL range, although I have seen a couple who were anesthetized but not dead and required more than that. How quickly it goes depends on whether there are premedications used or not. Premedicating with preanesthetic doses of xylazine or detomidine makes them go down more slowly, more like anesthesia induction, and take a little bit longer to die, while an unsedated horse goes down more quickly but may be more prone to reflexive actions/momentary CNS excitement like rearing up as they go down. IME, the faster the euthanasia solution is injected, the more rapidly and more smoothly they become anesthetized and go down.
In cases where the carcass is going to be fed to other animals - to feed foxhounds or zoo animals or dragged out into the back 4000 and left for the wild scavengers, when a layperson needs to euthanize a horse in an emergency, or in places where barbiturates are not available to veterinarians or are prohibitively expensive (like some South American countries), there are several other methods of euthanasia. A bullet or captive bolt to the brain done properly also drops a horse very quickly and humanely, but you have to know something about horse anatomy because their brains are smaller than you would think given their large heads, and people who do not know this sometimes end up with a live horse with the original problem AND a bullet wound to the sinuses. If a horse is anesthetized with other drugs, other ways I have seen to euthanize the horse include injection of a large amount of saturated KCl solution to stop the heart; laceration of the caudal aorta by inserting an arm into the rectum and using a scalpel blade to cut the aorta, leading to exsanguination into the abdominal cavity and death in 5-10 minutes; and insertion of a spinal needle into the cisterna magna (near the brainstem) and injection of a large amount of local anesthetic, which also causes death in 5-10 minutes. The latter is not on the list of AVMA approved methods but is used in some parts of South America where barbiturates are not available to veterinarians; it is chosen over laceration of the caudal aorta when a necropsy is desired.
I don’t remember if it made the papers or not, but there was an animal shelter in Cork City where people would take any stray animals they found. Thing was, you never saw an animal come back out of the place again.
A group of women became suspicious and a campaign was set up where they took it in turns to phone the place daily and ask if they could adopt a cat or dog, and every time they were told “no, sorry, we don’t have anything available”. One of them secured a job as receptionist in the place, and found out that any animal brought in was put to sleep within hours, or in some cases minutes.
Kittens and puppies were gassed in a tin box, adult cats and small dogs in a plastic barrel and bigger dogs in a larger plastic tank.
The sh1t hit the fan when a family’s pet dog went missing, they put up posters everywhere and someone saw the poster, contacted the family to tell them “I found your dog and took it to the pound” the delighted family raced around to the pound to reclaim their beloved pet and found she’d been put to sleep the same day she’d been delivered there.
I’ve no idea if the place is still open any more, I do know that the group of women went their separate ways and opened their own no kill shelters and sanctuaries (which is how I heard about the place in the City)