Alternate Rodent Cull Methods

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


  • 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. >_<


This is super helpful thank you!

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.


This is SO incredibly helpful thank you so much!


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.


Oh my, that’s so wild! I’ll bold that as well.

Yeah baby rodents are surprisingly durable considering how…well naked and pink they pop out