WARNING: Discussion of sensitive content (ie animal culling)
Hey all! Continuing to do more research for my future collection and wanted some feedback. I work in a rat lab, and for normal euthinasia we use Co2, but for animals that we need to harvest brain tissue from, we use rapid decap with a guillotine lever.
I’m being trained in properly using the lever, and of course my thoughts went to feeder rodents. Here are the pros/cons in my head between these two main methods
CO2:
Can cull multiple animals at once (+)
Relatively painless/stress free for the animal (+)
Requires several pieces of equipment (-)
Requires sourcing and refills for CO2 cannisters (-)
Rapid Decap:
Very quick and pain free for the animal (+)
Messy (-)
Would be difficult to use for smaller rodents? (-)
One at a time (-)
Obviously I see why CO2 is the more popular choice, especially when you add in that with CO2 you have a less direct hand in the euthinasia process. That being said, since I’ll probably be keeping and culling various farm birds as well, a guillotine lever might be useful, so:
Would a snake recognize a rodent as a food item if it has no head?
Would there be significant nutritional value lost with the head and blood being lost?
Would you be able to humanely euthanize a reptile in an emergy situation (ie severe incubation malformation) in this manner as well?
I’m just trying to make sure I understand everything I can about this process for my future self, thanks for any input!
Decapitation sounds great in theory for reptile euthanasia, but I think there’s a concern with brain activity still being possible since it would still be intact…
Most emergency euth on reptiles requires crushing the skull or pithing the brain and then making sure to further damage the tissues inside ideally with the aid of some sort of gas.
Reptiles are very well adapted to harsh conditions sadly. So it makes this difficult.
It would be handy for poultry.
Rodents… I feel like it can be mixed. Some snakes are super picky and ‘braining’ is needed. Less blood does mean some nutrition loss. And without the skull, it’s a bit harder to do some of the better methods for heating up f/t rodents (hairdryer method or dipping the head in hot water). Fresh kill eaters would probably be fine.
Personally… I’ve been using CO2 for my feeder rodents and it makes me the most comfortable. Although I did still feel terrible for needing to euth one of my favorite momma’s because of a fast growing mammary tumor. >_<
I’ll need to do more research as to what species decap is more humane for, I hadn’t considered the different nervous systems between reptiles and mammals causing different outcomes in terms of speed and painlessness
I can help with this, the AVMA actually has guidelines on euthanasia available in PDF format. While it’s meant as a resource for veterinarians, it does offer a lot of information.
Slowly working through this PDF (which is amazing and fully encompassing) and it echoes the feelings I had about CO2 (I had forgotten that CO2 is not as painless and distress free as gasses like Nitrogen)
“Advantages—(1) The rapid depressant, analgesic, and anesthetic effects of CO2 are well established.(2) Carbon dioxide is readily available in compressed gas cylinders. (3) Carbon dioxide is inexpensive, nonflammable, and nonexplosive and poses minimal hazard to personnel when used with properly designed
equipment. (4) Carbon dioxide does not result in accumulation of toxic tissue residues in animals fromwhich food is produced.”
“Disadvantages—(1) Substantial and conflicting differences in response to CO2 inhalation exist between and within species, strains, and breeds, making broad generalizations difficult. (2) Carbon dioxide, whether administered by prefill or gradual displacement methods, can be aversive to some species, and therefore potential exists to cause distress. (3) Because CO2 is heavier than air, layering of gas or incomplete filling of a chamber may permit animals to climb or raise their heads above the effective concentrations and avoid exposure. (4) Immature individuals and some aquatic and burrowing species may have extraordinary tolerance for CO2. (5) Reptiles and amphibians may breathe too slowly for the use of CO2. (6) Euthanasia by exposure to CO2 with O2 supplementation may take longer than euthanasia by other means.94,108,109”
This is mainly for people who don’t want to skim the article, but I bolded areas I am going to be taking heavily into consideration for my future cull methods and if they need to differ between species!
I think this one deserves to be bold as well. A lot of people seem to not be aware just how tolerant newborn mice and rats are to CO2, especially when compared to juveniles and adults. If using CO2 inhalation as the sole method of euthanasia, newborn mice can take up to 50 minutes of exposure before dying.
I remember using CO² to humanely euthanize a hen for a herd health check. I can say after sitting on the tank and it convulsed around and gassing it twice, I’m not that big of a fan. I can see why nitrogen would work better with its ability to cross the blood brain barrier without assistance. I am looking into breeding a couple of rats to keep my small population of snakes fed as i slowly expand into a working business and fresh killed is more nutritious than f/t rats for sure but has anyone done a long-term study on the possible side effects of elevated nitrogen in a snake’s diet?
Ultimately I would think with enough time to gas off, it would carry similar risks to CO2 exposure for the snake - as long as you let the carcass sit out to cool and gas off (without allowing bacteria growth by letting it sit out in warm temps too long), I THINK it would be fine?
But I don’t know of people who really go that route, I’m not sure if it has to do with the accessibility of CO2 v Nitrogen gas, or because Nitrogen gas is considered more dangerous in general because you don’t feel it getting into your system and displacing your oxygen
I know at my lab, travelling with a Co2 cannister and a nitrogen cannister are treated VERY differently because of how sneaky nitrogen overdose is, so perhaps that is why it isn’t commonly used? Or there may be another issue I am missing too
If I were to start a rodent colony right now (or even with your chicken example) I would personally choose cervical dislocation for the euth method, but this takes longer and is way more “hands on” than a gas bath, so most people don’t love it
Same concept but more ethically done, you place pressure in between two cervical vertebre (neck bones right behind the skull) in a quick steady motion to cause them to dislocate and break the spinal cord and brain stem - causes immediate and painless death when done correctly
There are special tools for doing this with different animals (i.e. rats, rabbits, chickens), or you can use your own tools like a broomstick for larger animals like rabbits and chickens
In a lab setting, animals are generally anesthetized first (with gasses much too harmful to use in a home setting for animal consumption), but for people who do it to eat meat rabbits or meat chickens, the animal being awake is fine, since it is so fast and painless once you get the technique down
Again, not super time efficient since you go one by one, and many people won’t like it since you are hands on killing the animal, but it involves no gasses and minimal extra costs, so it has its benefits certainly
In my lab, we put them under and then decapitate, which is a…similar concept, but too messy for home use probably
Here is a really good yet concise resource for what most university research labs consider as all viable and acceptable forms of rodent euthanasia these days - not all will apply to home use, but it is a great resource
This is not my institution, so this are not my exact IACUC (Institutional Animal Care and Use Committee) guidelines, but these are the sort of methods approved for animal scientists right now