Euthanasia by ethyl alcohol

[ozarkhellbender]

Azhael and I maintain that NOT all caudates are adapted to survive actual freezing. Species known to be able to are keyserlingii, the wood frog, and probably some others who haven't been studied yet. But not all of them, and possibly only a small minority.

Actually, I don't think anyone said ALL caudates are adapted to survive actual freezing. In fact, I never said ANY species actually survives having it's body frozen, I just said they survived freezing temperatures, which I have witnessed. The really funny thing is in my original post I said freezing was an invalid form of euthanasia, which everyone agrees on. We just can't agree WHY it's invalid.

 

[JacksonR]

I was pretty much joking...

Eljor are you calling me an obstruction? Cause I don't know what your talking about. Mostly because it's 2:00 in the morning....

 

[eljorgo]

I was pretty much joking...

Eljor are you calling me an obstruction? Cause I don't know what your talking about. Mostly because it's 2:00 in the morning....

I was not. You're interveniance was neutral in the hole thread I guess...?

Actually, I don't think anyone said ALL caudates are adapted to survive actual freezing. In fact, I never said ANY species actually survives having it's body frozen, I just said they survived freezing temperatures, which I have witnessed. The really funny thing is in my original post I said freezing was an invalid form of euthanasia, which everyone agrees on. We just can't agree WHY it's invalid.

Indeed nobody said ALL caudates were adapted to it and again nobody said nothing about they freeze with ice on their cells.
The point is always, always missed...
Review the post, see for yourselves...

 

[Azhael]

Nobody said anything about ice in their cells because that´s not even remotely how it works. In fact when we´ve talked about wood frogs and Salamandrella it´s been mentioned that their cells don´t freeze at any point, it´s only their extracelular medium. They DO freeze, just not entirely.
Such physiological adaptations have never been documented in most caudates, and that´s what we´ve been saying all along.
Now, if your argument is that a variety of caudates can tolerate below 0ºC without problems, and further more, without freezing at all, then that´s an even more spectacular adaptation than Salamandrella has. And you´d think by now somebody would have noticed that Salamandrella is not an absolutely extraordinary rarity.

I think, Ozark, that i understand what you are saying as i have myself seen amphibians laying dormant under ice, what we disagree with is their level of tolerance. You´d think they must be well below 0ºC when you find them in freezing conditions, but it´s not so. Like Molch said, take one of those highly sensitive digital thermometers and check both body temperature and inmediate surrounding environment and see the results. If their tissues are trully exposed to below 0 temperatures, species that have no physiological adaptations will freeze completely and very much die. No such physiological adaptations have been described for any other caudate other than Salamandrella (to the best of my knowledge).

Anyway, this is clearly not getting us anywhere and is quite off-topic at this point. As you say, we can at least agree that freezing is not an acceptable method.

 

[Jesper]

Decapitation.

 

[FRANCOIS]

I tend to agree with Molch and Azahel in this issue, when snow falls, not only do you get a lovely white blanket which constitutes especially on the mountains a vast reserve of water, but you also get an amazing natural protection against hard freezing of the ground and the vegetation is protected as a result. It's a matter of fact, it is called in some areas of Europe "the fertilizer of the poor"
Snow contains a lot of air and insulates very well. Even if the temperature outside drops well below freezing, the lower layers of snow will not get that cold.
Consider a foot of snow, if the outside air temperature is let's say minus 10 C, the upper layer of snow will reach such temperature, but the layer of snow just above the ground will stay at 0 C.
This is why roots, bulbs etc are protected under the snow from hard freezing and so would be a caudate. Expose most caudates to -10 C and they will die just like Molch said.
Of course I am not talking here about snow falling on permafrost and this is why there in no amphibians able to live / survive in such conditions like Molch indicated.

 

[Jennewt]

the ONLY reference that I can find to the use of ethyl alcohol is in Krieger Publishing’s “Amphibian Medicine and Captive Husbandry”. It is worth noting that this book does NOT provide a single reference for this.

I'm sure the info in the CC article was based on the “Amphibian Medicine and Captive Husbandry” book. In fact, the method is exactly as described there.

In looking for other references, I notice that there are many references for the use of 2-phenoxy ethanol to euthanize fish. I wonder if somehow this piece of information was corrupted by person-to-person communication over the years to just plain ethanol.

I have used ethyl alcohol as described in the article. It is slow, but I've never seen any signs of major distress for the animal. Maybe my judgement about distress is different than others. Certainly, it is distressing from the human point of view to see the animal still alive after 5 minutes, 10 minutes, 15 minutes... especially if you watch the whole time.

Based on the AMVA recommendations, the lack of any scientific references for the use of ethyl alcohol, and the experiences of several people posted here, I agree that we should remove it from the CC article. I'll try to get back in touch with the article's author and see if he agrees with the revision.

 

[Jennewt]

I'm also wondering if the article on CC should include carbon dioxide as an acceptable method of euthanasia. It seems to be widely accepted as humane. It is possible, even at home, to rig up an enclosed chamber with dry ice in the bottom, such that a small animal could be exposed to the gas, but not the coldness of the dry ice. I can buy dry ice at the local supermarket, but I don't know how common this is.

 

[kiathepooch]

I'm thinking of igloos/snow holes now.i know it's off topic but can anyone tell me if this is similar:you build an igloo/snow hole the snow on the outside is the temp outside,inside although still technically below freezing,can be considerably warmer than outside(I'm coming at this from a winter mountaineering point of view),if you had one person outside the gloo/hole they'd die off quicker than the person in the gloo/hole primarily due to the heat given off by the person inside which in turn affect the overall inside temp keeping it at a stable but low temp?prolonging the survival time....kinda rubbish but easy for me to understand example.

 

[FRANCOIS]

I'm thinking of igloos/snow holes now.i know it's off topic but can anyone tell me if this is similar:you build an igloo/snow hole the snow on the outside is the temp outside,inside although still technically below freezing,can be considerably warmer than outside(I'm coming at this from a winter mountaineering point of view),if you had one person outside the gloo/hole they'd die off quicker than the person in the gloo/hole primarily due to the heat given off by the person inside which in turn affect the overall inside temp keeping it at a stable but low temp?prolonging the survival time....kinda rubbish but easy for me to understand example.

Perfect exemple illustrating the insulating charachteristcs of snow!

 

[JacksonR]

Carbon monoxide would probably be even better. Numbs it, makes the animal fall asleep..etc.

Be harder to do and not as safe for a person to put down an animal. I don't know how you'd do it...plasctic tub with a hole in it that a car tail pipe would go into. lol Is it tail pipe...i'm not good with cars.

I'm also wondering if the article on CC should include carbon dioxide as an acceptable method of euthanasia. It seems to be widely accepted as humane. It is possible, even at home, to rig up an enclosed chamber with dry ice in the bottom, such that a small animal could be exposed to the gas, but not the coldness of the dry ice. I can buy dry ice at the local supermarket, but I don't know how common this is.

 

[Molch]

I never said ANY species actually survives having it's body frozen, I just said they survived freezing temperatures, which I have witnessed.

You THINK that will kill the salamander. However, I have no problem with testing it because I believe the caudate in question would survive.

but Oz, you yourself indicated you thought a caudate could survive a freezer. I mean, it's 15 to 20 below in there and it would freeze solid in minutes. Not even a wood frog would survive that.

anyways, enough of that freeze-thaw talk :lol:

By the way, if any of you ever want to turn this into a research study, there's potential funding in there. Two of my fellow grad students at the U of Alaska studied cryobiology - one in wood frogs, one in Arctic ground squirrels, who are the only known mammals who can lower their body temperature below the freezing point (without freezing). They had their projects funded by NASA . I guess NASA is interested in cryobiology to better preserve astronauts on that long trip to Mars

 

[Ed]

Bear with me as I've got to work backwards through a lot of this discussion.

As to the origin of ETOH (ethanol) as a euthenasia method the easiest thing would be to ask Dr. Wright. If no one else in interested in contacting Kevin, I don't mind doing it. He can be contacted via here Arizona Exotic Animal Hospital and while he can't send medications to treat animals over the state lines, he is happy to work with vets or even individuals on problems with thier animals. I haven't spoken to Kevin in a few years but he is a good guy with a lot of interest in herps.

Yes the source for the use of ETOH was from Amphibian Medicine and Captive Husbandry. On page 121 it has it's own seperate paragraph with a title so it isn't basedon a corruption of text. It also notes that ETOH was commonly used to preservation as not only does it fix some colors better but it doesn't result in some of the muscular distortions seen when 10% buffered formalin was used. It should also be noted that ETOH as a euthanasia agent was also rediscussed in the 2nd edition of Mader's Reptile Medicine and Surgery in the Amphibian section and the time line reported in that reference for the amphibian to become unresponsive is 15 minutes with a 10% ETOH solution.

With respect to some of the other potential agents like clove oil (eugenol), this needs to be dissolved in ETOH to create the bath as it isn't soluble in water by itself.

As for eugenol, there is concern that the eugenol would result in a plane of anesthesia that would make it appear to be dead only to recover after it was discarded. The most recent update to acceptable euthenasia methods for animals (see http://www.avma.org/issues/animal_welfare/euthanasia.pdf (it is effectively the same as the 2000 upodate) does not consider eugenol an appropriate method by itself due to lack of study. There are some more recent studies on using it as a method of anesthetic (see for example, Eugenol Anesthesia in African Clawed Frogs (Xenopus laevis) of Different Body Weights ) so some level of data would need to be researched before really considering it (also remember that it needs to be dissolved in ETOH before it can be used).

The use of CO or CO2 is not considered humane as amphibians can survive extreme hypoxia events (up to 27 hours) and freezing and boiling are not acceptable either due to the level of pain that the animal can suffer before succombing. Freezing is also not suitable for a variety of cold tolerant amphibians as this may actually not kill them only to have the amphibian begin to revive after being discarded.

Trauma as a method of euthanasia would require that the animal be killed on the first blow. Ideally the amphibian would be anesthetised before death.


I'm going to ask the basic question that seems to have been missing in this discussion... Why are we assuming that an increased activity level means that the amphibian is in pain? In the early stages of intoxication, increased activity is reported in other animals including humans, then the alcohol begins to depress the motor activity reducing coordination. Why is there the assumption that when these occur in amphibians exposed to 10% or less ETOH that they must be due to pain? When ETOH is used in higher concentrations, it is known to irritate the gills of fish, which is why the concentration of the solution needs to be carefully evaluated before using it with the amphibian. It would be incorrect to simply dump a strong alcohol into a container with the amphibian as concentration gradients are going to expose the amphibian to higher levels resulting in irritation. The solution should be made up ahead of time and be as close to the temperature of the water in which the caudate is residing to prevent thermal shock.

Some thoughts

Ed

 

[Molch]

Why is there the assumption that when these occur in amphibians exposed to 10% or less ETOH that they must be due to pain?

good point, but why assume that it doesn't? Conversely, why assume that an animal which remains still in a bath of alcohol or clove oil does not experience pain or discomfort?

The fact is, we just don't know exactly what the newt perceives. We can measure nervous system activity maybe, but the subjective experience of the newt is unaccessible to us, and probably always will be. The only truly objective measurement we have is the amount of time till death. So tentatively, I'd say the shorter the better.

 

[Ed]

good point, but why assume that it doesn't? Conversely, why assume that an animal which remains still in a bath of alcohol or clove oil does not experience pain or discomfort?

The fact is, we just don't know exactly what the newt perceives. We can measure nervous system activity maybe, but the subjective experience of the newt is unaccessible to us, and probably always will be. The only truly objective measurement we have is the amount of time till death. So tentatively, I'd say the shorter the better.

What we do know is that they do reach a plane of anesthesia where they do not react to stimili. This is a strong indicator of anesthetic effects. We also know that both provide numbness across multiple taxa...both due to human tests and responses and in lack of response to stimuli in other taxa so by definition, they are not experiencing pain unless it can be demonstrated otherwise as has occured with freezing.

I asked it as it in other taxa, increased activity can occur when intoxication with alcohol starts. This is also before we think about increased activity due to other stimulus.. none of which may have anything to do with pain. The reason I flagged it is because of the repeated implication that automatically associated it as a pain response. It is known that ethanol can stimulate the trigeminal receptors in multiple taxa so the caudates may be responding to a sensory overload... There are also some studies that indicate that caudates may be able to detect ETOH and avoid it as ethanol is of importance in the dealing with anaerobic metabolic effects (see for example http://www.mnf.uni-greifswald.de/fileadmin/Zoologisches_Museum/Hildebrandt/Dokumente/bickler07.pdf) and exposure to ETOH could indicate an enviroment where avoidence could be important.

There is nothing wrong with shortening the time for the anesthetic effect to occur but it may not be in the reach of all hobbyists.

In reviewing the article on clove oil, it should be stressed that about 1/3 of the salamanders in the treatment were not sufficiently anesthetized during the test which went on for a considerable length of time. As I noted above, the secondary consideration since it slows down the heart beat would be being able to recognize the difference between a heavily anesthetized salamander versus a euthanized one. If there is/was an inability to tell the difference a heavily anesthetized animal may recover and suffer after disposal. If clove oil is used, I would suggest once the caudate achieves the proper level of being non-responsive a more sure method to guarantee that the animal is euthanized be used, such as immersion in 75% ETOH.

Some comments,

Ed

 

[newtboyuk]

This thread has been quite active I see! I will need to have a proper read through when I get a chance but a few things stand out, all of which have been said by previous posters.

There's been a lot of back and forth discussion regarding the freezing issue and previous posters have also summarized the main point which is essentially the vast majority of caudates to the best of our knowledge are not directly exposed to the temperatures encountered in a household or commercial freezer and cannot survive it - in the time this takes, it has been shown that this is most likely to be a painful experience. It is possible, that there are some species with physiological adaptations similar to the likes of the wood frog that confer some freeze resistance and that we are not yet aware of them - if one goes by this assumption then freezing is still not acceptable.

As Ed has mentioned, clove oil is generally not described as a single method for euthanasia in the literature. Rather, its use is to provide complete anaesthesia prior to a more permanent method, be that chemical or physical.

I'm sure there was more but it's been a long weekend!

 

[Mark]

I’m still a little unsure what the conclusion was with regards to ETOH and it’s effectiveness as an anaesthetic for amphibians.

I have been unable to find ANY references in the literature to the use of ethanol as an immersive anaesthetic. There are a number of mentions of its use as an intravenous or oral agent in other species, but I have concerns about its efficacy via immersion, and its use in amphibians at all. Whilst I must admit to a certain naivety where the use of ethanol as an anaesthetic is concerned (I think that it is archaic?), I suspect that the osmotic gradient alone could cause severe electrolyte imbalances and damage (pain) to the animal in question, giving a fairly unpleasant death. How do we know that it isn’t just weakening and then killing these animals? As no studies seem to have been performed, I do not think that I could happily advocate this method of euthanasia as being humane, and with other much better alternatives in existence, I don’t think that anybody should be routinely practicing its use.

I can’t see that it would have any significant anaesthetic or analgesic (pain relief) properties. It probably just kills them slowly. As Liam has mentioned, all of the places that mention this method have based it all on the same reference which is outdated and should probably not be perpetuated. (Perhaps time to update the CC article?)

Yes the source for the use of ETOH was from Amphibian Medicine and Captive Husbandry. On page 121 it has it's own seperate paragraph with a title so it isn't basedon a corruption of text. It also notes that ETOH was commonly used to preservation as not only does it fix some colors better but it doesn't result in some of the muscular distortions seen when 10% buffered formalin was used. It should also be noted that ETOH as a euthanasia agent was also rediscussed in the 2nd edition of Mader's Reptile Medicine and Surgery in the Amphibian section and the time line reported in that reference for the amphibian to become unresponsive is 15 minutes with a 10% ETOH solution

 

[nwmnnaturalist]

Fascinating yet difficult subject. I've personally used a few steps in euthanizing any vertebrates in my care. I usually expose them to cooler temperatures, just to bring them into a torpor as much as possible. I then use a slightly blunt chisel to sever the brain stem and then complete with a hard blow to the rest of the brain. It's a very tough thing to do, but I cannot tolerate the idea of a creature suffering needlessly. I've done the same with captive fish as well.

On the subject of freezing temperatures, as someone who lives in Northwestern Minnesota, I am quite well experienced in the adaptations of our native reptiles and amphibians. To an extent, most amphibians are technically dead and frozen during the winter. The reason they survive is that cell activity continues thanks to the presence of glucose in the tissues. Basically an antifreeze. The only 'living' activity is on a cellular level. Other species of amphibians and reptiles also perform this miracle, but to a lesser extent. Wood Frogs (Rana sylvatica) are the most tolerant of these temperatures and exposure, as far as I know. Other species of amphibians and reptiles tend to seek subterranean shelter. For example, the peat and soil below marshes, along the lake shore and elsewhere (which actually remains warmer thanks to decomposition).

However, the process is a delicate one and is very difficult to replicate in an artificial environment. Years ago, when I was in high school, a substitute science teacher was planning on capturing Wood Frogs to use in an experiment replicating this. His idea was simply to bag up the live frogs, toss them in the freezer and try and revive them (or at least dissect them). I immediately protested, which he didn't take seriously until I contacted someone at the DNR and they reprimanded him for it. He couldn't understand what the big deal was. To replicate that miraculous process, it would require such careful planning and execution to mimic the temperature and daylight changes to incur the process. Not tossing the poor things in a freezer and letting them suffer a miserable death.

 

[Ed]

It should be noted that the torpor in this case has not impact on reducing the animal's ability to feel pain instead it just reduces or removes the ability to struggle.

As for overwintering in deeper strata, this can be due to multiple factors (not an all inclusive list) or combination of factors including getting below the frost line, or utilizing shallow aquifers (this is how timber rattlesnakes overwinter in the pine barrens of New Jersey (below the surface in cedar swamps with only thier head out of the water)) or using cover that functions as an insulating blanket.

With respect to the wood frogs there are seasonal variations in tolerance to freezing with the best tolerences in the late fall, winter and spring. As for tolerance to freezing, there a limits to what they can tolerate and wild collected wood frogs can be killed by exposure to temperatures lower than -3 C.

For those interested in wood frog freezing see woodfrogfreezing

Ed

 

[nwmnnaturalist]

That's pretty much why I put them into torpor. That way I can better ensure a clean strike.

One reason I always hope for a decent amount of snow is the fact we can get wind chill factors of -70F during the deeper part of winter. An example of them utilizing the substrate for shelter is an area near my home that has an outflow of water from a marsh that never freezes, not even in bitter cold. The temperature is consistently around 40F during the winter months. Snapping Turtles will burrow into the muck and silt in these seeps to hibernate. This also afforded me the chance of discovering a new population of an endangered species of caddisfly, Chilostigma itascae, which breed in these open seeps and only emerge on warm from February through April, when there is still plenty of snow cover.

It would be a fascinating subject to study the locations, substrates and depths these creatures utilize for hibernation, but I couldn't bring myself to disturb and expose them to the chill of winter.