Euthanasia by ethyl alcohol

[Ed]

There is always google scholar.... see what has been done before and look to see what is left..

Ed

 

[ozarkhellbender]

It seems the controversy over whether or not the temperatures within a normal household freezer would be low enough to kill a caudate has continued. I wasn't going to revive the subject myself, but it seems like others have.

I have been doing a little research on the subject, looking at both the Wood Frog and caudates. It was mentioned that Wood Frogs would not be able to survive the temperature range of a normal household freeze (-15C to -20C). My personal freezer runs a steady -15C. Now, I looked at the AVERAGE low temperature for a town within the Wood Frog's range: Fairbanks, Alaska. The AVERAGE low in the month of January (the coldest month) is -28.3C, which is considerably lower than a household freezer. Now, keep in mind, that is the AVERAGE temperature, not the record low. It was mentioned in this thread that permafrost would keep an amphibian from escaping the harsh conditions at ground level. The insulative properties of snow were also discussed. Personally, I have a hard time seeing the snow trapping in enough heat to keep the amphibian above the average temperature of a freezer, let alone above -3C. But hey, I could be wrong.

Now for the caudates. Let alone whether or not a Wood Frog could survive the temperatures of a household freezer, or whether or not caudates are exposed to subzero temperatures in the wild, I know of and have talked to people here in the United State who have frozen their caudates in a household freezer and revived them. The caudates in question survived unscathed and are, in fact, in breeding condition this year.

Now, we all know freezing a caudate is an invalid method of euthanasia. The question at hand: What is a valid method of euthanasia?

 

[Ed]

It . The insulative properties of snow were also discussed. Personally, I have a hard time seeing the snow trapping in enough heat to keep the amphibian above the average temperature of a freezer, let alone above -3C. But hey, I could be wrong.

I wouldn't be surprised if we looked into the literature for regional variations in survival based on temperature. I only dug around in it a little and there were some interesting studies that indicated at the very least that glucose content of the tissues shifted the temperatures that the frog could survive. Since this is controlled by genetics to no small part, it would stand to reason that regional differences would be found.

Now, we all know freezing a caudate is an invalid method of euthanasia. The question at hand: What is a valid method of euthanasia?

This is going to depend on what you consider as an authoritative source. The article I wrote all those years ago was based on the best available information at the time and not much of that has changed. It was edited to include eugenol (clove oil) which works as an anesthetic in a majority of amphibians (but not all)...

Ed

 

[SludgeMunkey]

I have been prowling this thread with interest!

From a personal standpoint, I find that a 20% Benzocaine solution, such as Oragel liquid, or Ambesol liquid to be the superior method when applied dermally to the ventral gullar region.

I am a bit shocked that no one noted that the primary ingredient of both forms of this is in fact ethyl alcohol, though the percentage varies a bit from brand to brand. These products do contain other ingredients, but the percentages are small enough in the mix I feel they are inconsequential to this topic.

As for clove oil, I remember reading years ago a paper that stated the effectiveness for fish was a result of it shutting down the O2 absorption by the gills resulting in death by asphyxiation. I do not believe, based on that, that clove oil alone is would be effective in caudates. (I am digging through my file cabinet for the print out, as I cannot seem to find it online at the moment. This could take a few days as there is about 12 years worth of animal related paperwork jammed into the thing...)

As for the use of "straight" ethyl alcohol, I suspect this is a slow death by toxosis rather than anesthesia followed by death. I suggest methyl alcohol as a faster option, even though it cause death through cell destruction by dehydration and is probably just as stressful to the animal.

As for the freezer method, this is a bit too slow for my liking.
Currently, on the rare occasion I am forced to euthanize an amphibian, I utilize an aerosol cryogenic electronic cleaner composed primarily of Freon 113. This results in instantaneous death by instant freezing. I achieve temperatures around -50C in less than three seconds. I would feel confident in stating that freezing solid at that rate is fatal even to notorious "frozen solid" hibernators like the wood frog and the gray tree frogs. I can personally verify this method does effectively euthanize Hyla chrysoscelis as I utilized it for numerous injured specimens removed from electrical panels at my old job. The corpse often thawed completely afterwards due to the extremely high interior temperature of the plant while waiting for disposal in the incinerator. Over a three year period well over 100 specimens failed to show any signs of life after a cryogenic freezing treatment.
This is the brand I use: http://hazard.com/msds/f2/bqj/bqjjr.html though there are plenty of others available. This is nearly the same mix used in the DIY wart freeze-off kits, and actually more effective as a cryo treatment. (Works great for busting welds and rusted nuts loose too, but is worthless as an electronic cleaner...)

 

[Cpt Crackers]

It's Thermodynamics' Kids!

I'm preaty much done with this. This is Zeroth law of thermodynamic. This part as any other part of physics is rolled by unchangeable facts.

Many thin layers of snow and ice, Air trapped between them. It works like a winter jacket, Heat generated on the inside (However little) cannot escape easily. It's all in the layering of the snow pack. The pack could cover their burrows and "Close the door" to the outside temperatures. (I plan an expedition to validate this theory) Then i assume they go into a slow state until like the others said, temperatures stabilize. Otherwise we wouldn't be seeing so many adult ambystoma tigrinum melanostictum up here. In Northern Canada. Winter reaches -30*c easily in December-February.

 

[nwmnnaturalist]

Re: It's Thermodynamics' Kids!

I can attest to the insulating nature of snow. I've built 'snow pile' shelters where you pile snow into a large mound and let it sit for a couple hours (to let the snow crystals settle and fuse), then dig it out. Quite comfy! Last year we had a wind chill factor of -73F in January, so I'm sure our creatures very much appreciate the snow's benefits.

 

[Ed]

As for the use of "straight" ethyl alcohol, I suspect this is a slow death by toxosis rather than anesthesia followed by death. I suggest methyl alcohol as a faster option, even though it cause death through cell destruction by dehydration and is probably just as stressful to the animal.

As defined the amphibians do become anesthetized from ETOH. The problem is that people are equating motion before becoming non-responsive as an indication of pain. This isn't necessarily the case as amphibians (and other animals) are known to go through a delirium or excitement phase during exposure. This is known to occur in multiple taxa and with multiple anesthetics. This is described in this discussion using benzocaine and MS-222 http://www.nwhc.usgs.gov/publications/amphibian_research_procedures/field_amphibian_anesthesia.pdf

This is the brand I use: http://hazard.com/msds/f2/bqj/bqjjr.html though there are plenty of others available. This is nearly the same mix used in the DIY wart freeze-off kits, and actually more effective as a cryo treatment. (Works great for busting welds and rusted nuts loose too, but is worthless as an electronic cleaner...)

This is analagous to immersion into liquid nitrogen which is covered in Amphibian Medicine and Captive Husbandry and other sources. The recommendation on this is that this should only be used on small specimens (imagine if you were to try it on a bull frog) as only small animals are likely to freeze before pain was detected.

Some comments

Ed

 

[caleb]

I have a hard time seeing the snow trapping in enough heat to keep the amphibian above the average temperature of a freezer, let alone above -3C. But hey, I could be wrong.

Soil temperatures are remarkably constant, even quite near to the surface, with or without a layer of snow above them. A quick google found this dataset of air and soil temperatures in Alaska:
Daily Soil Temperature and Meteorological Data for Sites at Toolik Lake Alaska

Picking (at random) the year 2001, and the coldest sample for which soil temperatures are available:
Air temperature: -19.8C
Soil moss temperature: -3C
Soil 5cm depth temperature: -2C
Soil 10cm depth temperature: -2C
Soil 20cm depth temperature: -1C
Soil 50cm depth temperature: 0C

So in this case, a wood frog would only need to crawl under the moss to be above -3C.

 

[Molch]

a good rule of thumb is that the soil a few feet down(and, if there's a good snow cover, probably much closer to the surface) rarely gets colder than the annual average temperature. Fairbanks, which has winter temps down to 50 below, has an annual average temp of 27 F, or -3 C or so.