Killing mice,CO2 and suffocation; what do you think?

Yesterday, I had to cull 4 adults mice but I didn't have my CO2 chamber yet and I was not able de kill them by throwing them on a wall

So I put a mouse in a little container and I let the mouse died of suffocation. They did not seems to suffer and just fall asleep. Since we put CO2 in their container when we have a CO2 chamber, and since what they exhale is CO2, is it the same thing to kill mice like this?

I find it easy to do. They die in about 15 minutes like this (really small container).

Thanks!

I dint know the answer, but if someone else does it would be great because i was wondering the same thing as i am currently starting to breed mice and it would save alot of money in the long run if i dint need to buy, (co2, hose's, new tank for chamber, remote Coyle's and things!)

Ok, let me see if I can get this right...

Hypoxia (low O₂ level) is quite unpleasant, and what causes the "panic" response. (Like when someone is dunking you under water.)

A high CO₂ level is deadly, but not unpleasant.

So:

When you euthanize mice in a CO₂ chamber they are konked out in a matter of a few seconds, and don't experience hypoxia. This is humane.

When you enclose them in a sealed container, they slowly use up the oxygen, converting it to CO₂, and slowly die (dunno whether it's of hypoxia or high CO₂ levels) which I think would be quite an unpleasant experience.

Feel free to correct me if I'm wrong on any of it.

Serp I think you hit the nail on the head (again), when any animal exhales the expelled breath is a mix of CO2 and Oxygen (among other gasses), thus taking a LOT longer to kill the mice as there is more available oxygen than a straight co2 chamber.

Traf, the "tank" for the kill chamber needs be nothing more than a tapperware type container with a tight fitting lid, costs less than a buck, just to clarify in case you were counting on an aquarium type "tank".

Using a CO2 tank, apart from being a quick and humane way of killing mice and rats, is also the first step to killing aerobic bacteria on these animals. The following freezing is an added safe guard to bacterial and other parasite infection.

Thanks. This is answering my question. I will build my CO2 chamber for the next ones.

Originally Posted by breedingcolors

Thanks. This is answering my question. I will build my CO2 chamber for the next ones.

That's a MUCH better option. The way you did it was actually very cruel. With a LARGE dose of CO2 so that almost all of the "air" is repased VERY quickly, the animal is actually "knocked out" before any jumping/thrashing/etc. occurs. Basically, it is "brain dead" in the sense that nothing is really getting registered BEFORE the painful looking stuff actually occurs. (That's what the past research has shown, anyway. SLOWLY increasing the CO2 level the way you just did it is similar to you breathing into a plastic bag for a long period (painful, and dangerous for you) - the gasping, breathing response, etc.

If you can't use CO2, use cervical seperation.

WARNING: CO2 doesn't work on pinks. They are pretty anaerobic, anyway. They have to be to live under a mom for so long! Universities can't legally CO2 pinks at all - they MUST use cervical separation (or another approved method). They do it by cutting the head off.

KJ

Originally Posted by Serpwidgets

Hypoxia (low O₂ level) is quite unpleasant, and what causes the "panic" response. (Like when someone is dunking you under water.)

A high CO₂ level is deadly, but not unpleasant.

So:

When you euthanize mice in a CO₂ chamber they are konked out in a matter of a few seconds, and don't experience hypoxia. This is humane.

When you enclose them in a sealed container, they slowly use up the oxygen, converting it to CO₂, and slowly die (dunno whether it's of hypoxia or high CO₂ levels) which I think would be quite an unpleasant experience.

I can't agree with you.
When you are drowning you are experiencing HUGE and FAST O₂
deficit, you can't breathe so you are panicking.

It can be compared to using CO₂ chamber with valve 100% opened. CO₂ displaces oxygen really rapidly, just like water in the example above. Mouse is trying to breathe, it's lungs are working, chest too, but nothing happens.
Slow raising CO₂level is another story. Mouse can't notice it, it feels only sleepy, more and more sleepy. When it falls asleep then it is the time to open valve to finish work.

On the other hand I'm not supporting the idea of leaving mice in jar and wait till oxygen rans out. Are you sure that those mice were really dead, not just deeply stunned? I prefer to keep everything under control and this method leaves far too many things uncertain.

@sojkas:

Here's what the NYU school of medicine says:

Guidelines for Performing Euthanasia via C02
For rodent species, CO2 is an acceptable form of euthanasia when used under the following guidelines:

We do not recommend prefilling (precharging) the euthanasia chamber with CO2, since high concentrations (>70%) can cause nasal irritation and excitability. Rather, the animals should first be placed into the chamber, followed by the addition of CO2 at a low flow rate (20% of the chamber volume per minute) to complete the process. Rapid gas flows should be avoided since excessive noises ("winds") can develop and induce excitement/distress in the animals.

Place the animals into the chamber and turn the red lever until you hear gas flowing at a low rate.

Gas flow should be maintained for at least 1 minute after apparent clinical death (approximately 5 minutes total). A timer should be used to ensure adequate length of exposure.

It is important to confirm that an animal is dead after removing it from the chamber. This may be accomplished by assuring lack of heartbeat or by performing cervical dislocation following CO2 narcosis or creation of a pneumothorax following CO2 narcosis.

According to the 2000 Report of the AVMA Panel on Euthanasia, "Compressed CO2 gas in cylinders is the only recommended source of carbon dioxide because the inflow to the chamber can be regulated precisely. CO2 generated by other methods such as from dry ice, fire extinguishers, or chemical means (e.g. antacids) is unacceptable."

Only one species at a time should be placed into a chamber, and the chambers must not be overcrowded. Animals must meet the minimum space requirements listed in the "GUIDE" up until the time of euthanasia. When placed into the chamber, all animals must have floor space.

Euthanasia should always be done in cohorts (live animals should not be placed in the chamber with dead animals).

Chambers should be kept clean to minimize odors that might distress animals prior to euthanasia.

Animals must not be euthanized in animal housing rooms, except under special circumstances such as during quarantine for infectious disease agents.

Neonates: Since the time period for euthanasia is substantially prolonged in neonatal rodents (rodents 13-16 days) inherent resistance to hypoxia, CO2 narcosis must be followed by decapitation after the animals lose consciousness.

Sounds like they agree with your idea of not blasting it right away.

I thought this was rather interesting too:

Animals must not be euthanized in animal housing rooms, except under special circumstances such as during quarantine for infectious disease agents.

Mice are smart enough to learn by watching other mice. For example, when other mice see one of their buddies step onto a mousetrap and he is killed, the observers will show mortal fear of mousetraps from that time forward. They might learn that "the CO2 chamber is a death trap" by observing, too.

IMO the most important thing, if you're goal is to be humane, is making sure that the way you do it does not cause them to panic at any point. The guidelines quoted seem to reflect this, too.

When you are drowning you are experiencing HUGE and FAST O2
deficit, you can't breathe so you are panicking.

It can be compared to using CO2 chamber with valve 100% opened. CO2 displaces oxygen really rapidly, just like water in the example above.

This I can't agree with. CO2 does not displace oxygen, they are independent of each other. CO2 is dissolved in the blood, buffered by conversion to and from bicarbonate, and crosses into the alveolus 100 times more easily than Oxygen. Oxygen is barely dissolved in the blood, being mainly carried by hemoglobin. It can be displaced by Carbon Monoxide CO, but not CO2. It doesn't bond hemoglobin.

Panic due to suffocation / drowning is caused by hypoxia (too low of oxygen), regardless of what the CO2 levels are doing. Gradually raising CO2 in the face of plenty of oxygen at first causes an increased heart rate and respiratory rate in response to metabolic acidosis, then a threshhold is reached and the heart and respiratory centers are suppressed.

Originally Posted by Hurley

This I can't agree with. CO2 does not displace oxygen, they are independent of each other. CO2 is dissolved in the blood, buffered by conversion to and from bicarbonate, and crosses into the alveolus 100 times more easily than Oxygen. Oxygen is barely dissolved in the blood, being mainly carried by hemoglobin. It can be displaced by Carbon Monoxide CO, but not CO2. It doesn't bond hemoglobin.

I was effering about CO<sub>2</Sub>displacing air in tank, not in blood.

Originally Posted by Hurley

Panic due to suffocation / drowning is caused by hypoxia (too low of oxygen), regardless of what the CO2 levels are doing. Gradually raising CO2 in the face of plenty of oxygen at first causes an increased heart rate and respiratory rate in response to metabolic acidosis, then a threshhold is reached and the heart and respiratory centers are suppressed.

Well, I can say only what I've observed. When CO<sub>2</Sub>is being added slowly mice just fall asleep. I know that this is the way mice are treated in Unversity I was studying as I was curious and I asked about it.