• Looking to buy a cephalopod? Check out Tomh's Cephs Forum, and this post in particular shares important info about our policies as it relates to responsible ceph-keeping.



Sepia elegans
Staff member
Moderator (Staff)
Feb 1, 2007
Des Moines, Iowa
Many people have to make the decision to euthanize pets such as dogs and cats. Does anyone out there euthanize their cephalopods if they begin to show vast deterioration and extreme lethargy? The reasoning for both animals would be the same; euthanasia is the humane way of putting down an animal that may be "suffering".

Just throwing this out there.

I have been thinking about it all day! I read on an old thread that a bowl of ice and a little water will slow HR and the ceph will pass in about 3-5 seconds....
This hits home. I think it was Ink who lingered on weeks after she started deteriorating. She was one of the abnormal who laid eggs and continued to eat while guarding them and then lived weeks after the eggs disappeared. I was releaved when she finally passed as it was torture watching her aimlessly pace the tank as her body deteriorated. Had there been a humane way to end what I perceived as her suffering, I would have as I have taken all sorts of creatures to the Vet to humanely end their suffering.
A colleague and I wrote a paper on the subject of using benzocaine as a euthanizing agent for Enteroctopus dofleini (link coming). The benzocaine is the same benzocaine found in many antibiotic creams that humans apply. The cause of death is through terminal anesthesia; the animal just goes to sleep. This method has garnered support from many people; it is the preferred method for both GPOs and cuttlefish at Moody Gardens. The results on cuttlefish were very, very rapid with the benzocaine taking a matter of minutes while the GPO (it being a cold water animal and all) took nearly 60 minutes.

Freezing is still considered humane but may take some time. You can also utilize ethanol (or other alcohols) to anesthetize the animal and then freeze it. There is some evidence to show that simply freezing the animal without sedation may be "inhumane". One of the reasons that GPOs are often frozen is that the amount of alcohol to kill the animal would be very costly so in that case the animal is sedated and then frozen. Benzocaine is fairly cheap and quite effective.

What would the dosage of benzocaine be for a medium sized octo (not sure how much the average captive octopus weighs)? Also how would you go about medicating the animal? My guess would be that it would not be done in the show tank, though a fair amount of carbon may be able to take the medication out after the octopus (or cuttlefish) is gone.
Here is the link to the journal.


I believe it is on page 8.

The dosages given in the paper can be extrapolated out for smaller octopuses. Species such as Octopus bimaculoides, and the like, may only require 25% of the concentration needed to euthanize GPOs, as the water temperature is greater which will induce a quicker uptake time. Smaller octopuses are many times euthanized via ethanol because the volume needed is much less than the larger octopuses (due to the large containers that these larger octopuses occupy). Please note the descriptions of the octopuses behavior during the trials. While it may appear that the animal is "suffering" its behavior is actually normal for this procedure. Many marine animals, especially fishes, will go through an excitement phase before they expire and while this may appear inhumane, it is merely a normal reaction occurring. Because benzocaine works as an anesthetic agent you can (from my observations) rest assure that the specimen is not in pain during the procedure.

The two GPOs used were both in senescence and were euthanized in a large garbage can off exhibit. Sepia pharaonis and Sepia officinalis were euthanized in a 4 L container off exhibit. These combined results will be published fairly soon as well as results for another cephalopod species (knock on wood).

The weight of the specimen is irrelevant when determining dosages for baths. Treatments via baths are dependent upon water volume while IV injections, and the like, are dependent upon weight. You are dosing the water with the benzocaine, or what have you, not the animal. Factors that may cloud this are temperature and pH but concentrations between different sized animals (given temperature and pH are the same) should be equal.

This may be way off base and have no meaning but I was so afraid that Trapper (female mercatoris) would decay while alive and I know I couldn't euthanize (I had a beloved seahorse that I should have but just could not) that I tried giving her a small amount of antibiotic for two weeks while she was brooding. She became very weak after surviving the hatching 11 weeks but her skin never developed sores (she lost the ability to color and her arms seemed to shrink in thickness) and she stayed moderately active. Even her final walk during daylight lasted over a week. What I don't know is if the antibiotics made her final time less painful or if they did anything at all so I guess I am asking if you know of other similar attempts and the outcome. I have a brooding female now that is difficult to feed and I have not tried gut loading what I can get to her but, after reading about Alexandria's end, am considering an attempt.
Pain. I have very strong feelings of actual pain felt in animals (humans included), let alone invertebrates but I really do not want to open up that can of worms, yet...

When senescent symptoms set in and are visually seen, it can be deduced that the internal infection is severe. When internal organs begin to deteriorate bacteria accumulates. Very soon the bacteria will reach the circulatory system and become systemic. This condition is very difficult to treat in any animal and is often times fatal. Antibiotics may give the immune system enough strength to add some time to its life but I do not see how antibiotics can lessen any "pain" felt on the animal. If pain is a consideration, then look at it from this viewpoint; antibiotics may lengthen life span but may lengthen this life span at a consequence to the animals' pain by prolonging its life in this condition.

Systemic infections can only be cleared up if the animal has the strength to heal itself after the antibiotics have taken control. In an animal is deteriorating from the inside-out, the antibiotics may clear up the infection momentarily but the internal anatomy will still be prone to future bacterial infections and the cycle will continue.

I do not recommend antibiotics of any kind when all the facts point to senescence.

Your points and emphathy are well noted but ... If the antibiotics given before deterioration started taking its toll and allowed her to die by just going to sleep, I would want to continue with the practice. I just don't KNOW that this was the effect. Visually, she was still in good condition (with the exceptions noted but fraility is not necessarily extreme pain) and she was moving on her own, not flopping around in the tank. The extended life is not what I am hoping to achieve but wonder (if there is any relationship at all) if it is not a sign that it provided a better end.
I have yet to read the paper so I don't know if it is mentioned in there or not; Is 4 liters the volume of the container the cuttlefish were euthanized in or was that a typo on your part? That would be roughly 1 gallon, which I would guess is too small for the cuttle to occupy.
The paper only details the trials with Enteroctopus dofleini. The paper to come will include further data.

To answer your question, yes it was 4 L. The container was a large bowl-shaped container with a lid. As the decision was made to euthanize the specimens, there was no need for any container larger than that. As I said, the cuttlefish were euthanized in about 2-3 minutes. A main goal of the study was to provide cost effective alternatives to euthanasia, thus using the smallest amount of water (and consequently less additives) would yield the best results for the study. The specimens were about 20-25 cm. When they did bump into the bowl, the direct force was not felt as the slant of the bowl allowed for some deflection. Given the quick time in this method, I feel that no more water is necessary for this.


You would have to check the chemical composition of the antibiotics to determine if there are any anesthetic components in it that may alleviate or numb the pain. If the bacterial infection was subdued by the treatment, this alone would not guarantee that no additional pain was felt as the primary complications (the internal breakdown of systems) would still be present. Ths is very interesting to discuss.

Boy, that raises a lot of tricky issues... one of the reasons I like learning about cephalopod nervous systems is that they're so different from us, so I'm thinking that it's hard to know how much our own sense of what "pain" and "consciousness" and "awareness" and "suffering" mean carries over to cephalopods. I'm pretty sure that most of us agree that those words have some meaning for cephs, but the way their nervous systems work is different enough that it's hard to know if their experience of anything is analogous to ours.

One thing that comes immediately to mind is that, AFAIK, there is no blood-brain barrier in cephalopods like there is in vertebrates. So any chemical that's in their bloodstream or tissue, can directly effect the neurons of the brain. But also, the nervous system has a lot of peripheral ganglia that respond to stimuli, as well, but are sort of autonomous... the brain is known to be responsible for learning, and it's probably safe to say it handles awareness and consciousness as well, so maybe the place to draw the line of "feels pain" is "brain receives a signal of pain" but severed arms will show some responses to stimuli, including and "ouch" like withdrawal from uncomfortable stimuli, without any connection to the brain at all. Is making a severed arm "feel pain" something that should be avoided?

Although I find that argument about pain related to internal infections and organ failure to be plausible, I can also imagine other plausible views... there are a lot of human organ ailments that have little or no pain at all, because we don't really have detectors for some things that can go wrong, like holding your breath when you're coming up from a deep SCUBA dive(!), but other ones, like kidney stones, where internal organ problems cause immense pain.

I don't know if there have been any studies that determined criteria for measuring the pain or discomfort level for cephs... we know anecdotally that octos will try to climb out of their tanks more if the water quality is bad, and they'll certainly try to escape if you poke them or annoy them. So they seem to have ways of expressing displeasure at outside sources of pain, but it's not really clear to me how to tell from their behavior whether they're "frail but happy" and wanting to be pampered in their last days, or "miserable and despondent." Maybe some octo-keepers have a sense of this... I guess there have been a number of studies which I've only seen referred to in books like Hanlon & Messenger that studied senescence (like the one that showed a delay in it when the optic gland was removed)-- do those provide any behavioral criteria for assessing senescence or quality of life? The table at the end of Greg's article has some criteria for "stages" and "planes," and it sounds like that's the accepted standard, but it seems to be more about level of consciousness than any sort of "quality of life" assessment or chronic pain and suffering, or even the cephalopod's experience of what's happening in the short or long term.

Even in humans and mammals this stuff is pretty poorly understood, and has a lot of weird rationalizations of morality, correctness, and so forth that I find are more emotional than rational... a lot of anesthesia doesn't so much prevent pain as much as it inhibits memory formation, so the patient may be in agony during the operation, but doesn't remember that afterwards. Are these sort of things immoral because the pain is momentarily experienced, even if there's no memory of it later? They seem to be established as acceptable. And I've heard (although possibly from unreliable sources) that it was an accepted belief at some point frighteningly recently that babies didn't need anesthesia because they don't experience pain, or at least that they don't remember it or it doesn't count or something... which, of course, the babies didn't argue with, but when someone came up with (obvious) things to look for, they noticed that babies given anesthesia before surgery seemed to be showing less signs of extreme discomfort.

I'm intending all these questions as inquiry and investigation rather than criticism of any position... I'm trying to raise questions that have some bearing on the discussion about antibiotics for life extension as either an extension of the animal's experience of life or experience of suffering, but I don't really know how they fit in to reaching some sort of conclusion... heck, we as a society can't even decide on who gets to make what decisions and by what criteria for people, who we can probably assume experience pain and suffering and awareness and consciousness just like the rest of us, on life support or with fatal illnesses or who have been condemned to death.

Getting a bit far afield of cephalopods, I read recently that when Richard Feynman was going through cancer treatments, he was concerned that he couldn't make an objective decision on when to stop fighting the cancer and give up, so he arranged that when he thought he should stop his own treatment, he'd ask his wife and sister if they thought that was appropriate, and if either of them thought that he was suggesting it out of temporary depression or something, they would be a check on the decision. When they all agreed that the time had come, he asked the doctors to stop the extreme measures preventing the cancer from taking its course. I have mixed feelings about this (it seems to put one's loved ones in an uncomfortable position) but it does address some of the sticky issues.
monty;104493 said:
And I've heard (although possibly from unreliable sources) that it was an accepted belief at some point frighteningly recently that babies didn't need anesthesia because they don't experience pain, or at least that they don't remember it or it doesn't count or something... which, of course, the babies didn't argue with, but when someone came up with (obvious) things to look for, they noticed that babies given anesthesia before surgery seemed to be showing less signs of extreme discomfort.

I shortened your wall-of-text a little to comment on this part. There have been studies that babies that are not given anesthesia show an increased sensitivity to pain during immunizations later on.
Merely witnessing an octopus retract an arm when some harm has come to it does not constitute pain to me. It is a reflex. The nerves "realize" something is wrong and if the octopus continues performing this negative action its fitness level will drop, thus the octopus pulls back. Much like humans do if they were to touch a hot stove. You do not actually think to yourself to remove your hand, it is a reflex. Once your hand is removed, apparent emotions may overtake you and you may begin to cry for help. That is the tricky part: separating pain from emotions. Many times you may be hurt and not realize it until you look at it. Then fear may set in and you begin the emotional roller coaster. Crying may just be a simple way of asking for help from somebody; merely a reaction to a physical distress.

Back to antibiotics. I know that it can be hard for hobbyists to deduce what types of bacterial infections, if any, may be going on, but I have always been under the idea that antibiotics should not be given to anything without clear facts of an infection. The aquaculture industry is experiencing this first hand as many fish are given drugs without any basis, merely a proactive approach. I believe it was in the Great Lakes region that some fish were beginning to develop immunities to certain parasites. This can also happen with cephalopods although the short life span may not render the absolute conclusions visible, throwing antibiotics around is not a good habit to get in to (even though some doctors just love it).


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