Animals and pain

[nizmo]

I have noticed that animals appear to be less sensitive to pain than humans... Like when the dog does something stupid and hurts itsself, it looks extremely painful but the dog doesnt even seem to care.

 

Is it possible that animals have evolved over time to be less sensitive to pain? Considering that in the animal kingdom, most animals suffer extremely painful looking deaths...

[Cap'n Refsmmat]

Or perhaps they communicate pain in ways we don't understand -- not all animals express pain by moaning and whimpering and rubbing the affected region. Expressing pain as an animal is probably a disadvantage -- it indicates to predators that you might be easy to eat.

[Daecon]

Maybe they just don't make as much of a fuss about it as humans do.

 

Which can be very frustrating if you're a vet trying to make a diagnosis, I imagine.

[thedarkshade]

I have noticed that animals appear to be less sensitive to pain than humans... Like when the dog does something stupid and hurts itsself, it looks extremely painful but the dog doesnt even seem to care.

 

Is it possible that animals have evolved over time to be less sensitive to pain? Considering that in the animal kingdom, most animals suffer extremely painful looking deaths...

It might actually just look like that. After all, the reaction toward an excitation depends on the rate of electric impulse it causes.

 

It's all a buch of nerves!

[falcon9393]

maybe animals cant express pain as much as humans can so maybe they are like crying on the inside or sumthin like dat!!!

[SamCogar]

It is my opinion that animals can "control" the pain (turn it off) much, much better than humans can.

 

They sense the pain when the injury occurs (a dog will yelp and even bite when the injury occurs) but then they "turn it off".

 

Humans can do this in at least two (2) instances that I am aware of.

 

One is when a really traumatic injury occurs, they will "turn everything off", ..... a condition described as "being in shock".

 

The other one occurs when one is in a "highly exicited state" (adrenalin rush) or when they are "intentely concentrating" on something physically they are doing. This occurs quite often, ...... like when you look at someone, ..... or they look at you ....... and blood is streaming down one's arm or leg and when ask "What did you do?", ...... the answer oftentimes is, ..... "DUH, I don't know, .... it doesn't hurt."

 

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[thedarkshade]

It is my opinion that animals can "control" the pain (turn it off) much, much better than humans can.

I'm not sure if I'm following right here, but the only way to turn the pain off is to stop feeling it any more, and you do that only when you have no electric impulse going through your nerves!

 

They sense the pain when the injury occurs (a dog will yelp and even bite when the injury occurs) but then they "turn it off".

The dog will keep yelping as long as he feels the injury. It will stop yelping only when the pain effect starts to wear off!

 

The other one occurs when one is in a "highly exicited state" (adrenalin rush) or when they are "intentely concentrating" on something physically they are doing. This occurs quite often, ...... like when you look at someone, ..... or they look at you ....... and blood is streaming down one's arm or leg and when ask "What did you do?", ...... the answer oftentimes is, ..... "DUH, I don't know, .... it doesn't hurt."

It does hurt. It's just that you're far more concentrated at something else and your reflex toward the excitation needs no concentration, it happens in a instinctive way!

[iNow]

As has been stated already, the fact that we are too communicatively inept to see it does not mean that animals are somehow less sensitive to pain. That's a complete non-sequitur.

 

Also, which animals? That's a pretty enormous list from which to choose. Can you at least limit it to either land based or ocean based?

 

 

 

To the comment in the OP about dogs...

 

Dogs are pack animals, nomadic and travel together. If one got hurt, it either "cowboyed" up and dealt with the pain and kept up with the pack or it died. Those that sucked it up survived by staying with the pack were the ones which lived to pass on their genes.

 

Humans have had different evolutionary pressures. We are pack animals too, but we are not nomadic/hunters/explorers in the territorial way that dogs (wolves) are. When we cry and moan and make a big deal about pain, we get help from the community. So, humans have evolved to be a bunch of wussies and make as much noise as possible when in pain.

 

 

Dogs... suck it up or die.

Humans... cry like a bitch and get a lollipop.

 

 

None of this, however, means that the dogs are less "sensitive" to pain, only that they've evolved a different response to it.

[vampares]

We humans have the ability to learn from our mistakes (most of us anyways). Our reaction could be part of that learning experience.

 

Animals learn but far less quickly, and there is less to learn from it. It may as well be better to not be so affected so that they can run, etc. A pack animal, like a dog/wolf, benefits from the appearance of having won a fight.

 

Humans get themselves into more predicaments and benefit more from being rescued.

[bascule]

How can you quantify the perception of pain in regard to "animals"?

 

How pain is perceived will vary greatly from species to species...

[SamCogar]

It does hurt. It's just that you're far more concentrated at something else and your reflex toward the excitation needs no concentration, it happens in a instinctive way!

 

Now Darkside, if "it does hurt", ........ but you do not "feel the pain", ..... then it is apparent that your body and/or your brain somehow "turned the pain off". Which proves to me that humans and other animals are capable of "involuntary pain management". Now if we could just figure out how to voluntarily (consciously) do that, ….. we could save a fortune in “pain medications”.

 

In that “pain” almost has to be classified as a “survival trait” that came about due to evolution’s “survival of the species” thingy, then one almost has to assume that all animals that suffer a bodily injury that could be “life threatening” would also “feel the pain” of that injury or any injury. A localized group of “injured” cells could not very well be selective in knowing if the injury to them would be “life threatening” to the organism as a whole, the individual animal. All should be able to “feel pain” except those species that evolved an extremely high “reproduction strategy” as their survival trait, such as fish, frogs, crabs, etc. (multiple live birthers or egg producers)

 

Given said, then one has to assume that each species of said animals evolved their own “pain management” techniques when an injury occurs. Thus, an animal, including humans, only experience the “hurt” or “pain” of an injury because the injured cells transmit a chemical/electrical “signal” via the nerves to the spinal cord, then and/or the brain stem, then and/or the brain. (I worded the aforesaid as such because I do not know for a fact that all the nerves in one’s body are directly connected to the spinal cord.)

 

And said “pain” will only continue to be “felt” by the animal as long as: 1) the injured cells keep transmitting said “signal”, 2) until said cellular transmission is halted by another process, and/or 3) if the nerve itself transmits “false pain signals”. (# 3) is sometimes experienced by people who have had all or a portion of an arm or leg amputated.)

 

And given that each species has “evolved their own ‘pain management’ technique”, …. their means of curtailing said “pain” is anyone’s guess.

 

Orcas are also “pack animals” and I will have to assume they also feel pain, ….. or so they imply that Orcas do, to wit: ”The pod members protect the young, the sick and the injured.”

 

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[thedarkshade]

Now Darkside, if "it does hurt", ........ but you do not "feel the pain", ..... then it is apparent that your body and/or your brain somehow "turned the pain off". Which proves to me that humans and other animals are capable of "involuntary pain management". Now if we could just figure out how to voluntarily (consciously) do that, ….. we could save a fortune in “pain medications”.

First of all, it's darkshade!

It's simply an ignorance toward the pain. That does not make the pain smaller! And our reaction toward that pain in that case would be instinctive and unconscious!

 

Given said, then one has to assume that each species of said animals evolved their own “pain management” techniques when an injury occurs. Thus, an animal, including humans, only experience the “hurt” or “pain” of an injury because the injured cells transmit a chemical/electrical “signal” via the nerves to the spinal cord, then and/or the brain stem, then and/or the brain. (I worded the aforesaid as such because I do not know for a fact that all the nerves in one’s body are directly connected to the spinal cord.)

The simplest rule of what you call a "pain management" is to move away from what causes pain. That's not a hard thing to do, all animals do that! The difference it that we know it will hurt, so we can avoid it in various ways.

[SamCogar]

First of all, it's darkshade!

 

thedarkshade, I apologize for not keying your screen name correctly, it was not intentional, I assure you. If it had been I would have used something more “original” like ……. oops, better not do that.

 

The simplest rule of what you call a "pain management" is to move away from what causes pain. That's not a hard thing to do, all animals do that! The difference it that we know it will hurt, so we can avoid it in various ways.

 

thedarkshade, what you describe therein, ........ I myself would call "pain avoidance". Ya know, like "stay away from it", ...... "avoid it", ........ and then it won't hurt ya.

 

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[lucaspa]

How can you quantify the perception of pain in regard to "animals"?

 

How pain is perceived will vary greatly from species to species...

 

And it is perceived very differently from human to human. Medicine has the "pain score" of 1 - 10 of how much pain a person is in. Given the same injury or chronic pain, different people say they have VERY different levels of pain. I've seen studies where the responses vary from 1 to 10!

 

This discussion is about 2 things. Ostensibly it's about how much pain other species feel.

 

BUT, the only way we can determine how much pain an individual feels is for them to communicate it to others. So we look at animal behavior and try to guess whether, and how much, pain they feel. Because the animal can't tell us. And the behavior can have other causes: fear, anger, defense, etc. I've seen rats react violently to being picked up and held if the person moves very quickly. The behavior is one that is very similar to a pain response. However, if a rat is used to a behavior, even one that should be painful, there is no behavioral response. For instance, I witnessed one experiment where the researcher would inject into the abdomen every day. He would just come in, grab the rats by the scruff of the neck and the rats would just hang there. Then he would jab the needle in the abdomen and make the injection. Still the rats would just hang there. No reaction at all. No squealing, squirming, avoidance, anything! Were they in pain? Logic says "yes" but the observational data says "no".

 

This is complicated by a point made by SamCogar: our human perception of pain depends on circumstances. There is ample documentation of people in war who suffer horrendous trauma but don't feel any pain at the time. In other circumstances, even it is equally documented that minor injury can have a person screaming in agony.

 

Now, the nerves must be conducting the pain signals, but some mechanism in the brain either interferes with the perception or augments the perception.

 

So, back to the OP: "Is it possible that animals have evolved over time to be less sensitive to pain? "

 

Possible, but not likely. Remember, we use animals as models for understanding the physiology of pain. That we can relate that research to alleviating human pain argues that the nerve response in animals is equivalent to humans.

 

Also remember our own evolutionary history! For all but the last few decades of our history individuals suffered daily trauma and disease was much more common. WE should also have evolved to be just as "less sensitive" to pain as any other species. Why would human evolution in regard to pain be any different than any other mammalian species?

[thedarkshade]

Don't worry Sam, it's all fine!

 

And lucaspa, I think you got a point! When I read your post, the first thing it came to my mind was the hard fact that I had to get used to getting up very early in the morning to go to school after a long holiday! I guess we all (including animals) get used to every kind of stuff!!

 

Cheers!

[Revenged]

Animals are used all the time to model pain...

 

As someone mentioned before when we are in the clinic we ask people to state their pain between 1 and 10.

 

But this method is rubbish, especially if you want to invest money into a costly clinical trial.

 

This is why most of the evidence from the effectiveness of pain killers is from animal models (before they ever reach clinic) since it is hard to read people's pain and it is very subjective, varies dramatically and can be influenced by hundreds of other factors.

 

Fortunately animals are actually extremely good models, which is rare when you deal with the nervous system.

 

Most disorders of the CNS are impossible to model in animals - Alzheimers, Parkinson's, schizophrenia (the models used are very poor)...

 

The exception may be epilepsy (but even with best knock-out mice studies and EEG recordings it is difficult to come to any firm conclusions)...

 

This is perhaps one of the reasons why we have had no major breakthrough in treatments for epilepsy. The first line drugs (valproate, ethosuximide, carabamazepine) have been around for decades.

 

However, with pain many new drugs are available and widely used.

 

e.g. Gabapentin development for neuropathic pain (i.e. nerve pain)... it is making zillions because most of the drugs (NSAIDs, glucocorticoids) are only effective in inflammatory pain and it was the only real treatment for nerve pain (e.g. diabetic neuropathy, spinal cord damage, sciatica...etc.)...

 

pretty surprising considering it was discovered by chance... the drug company developing it made gabapentin to act on GABA receptors... it worked on neropathic pain but after a few years of work it was found to acts on calcium channels and not GABA... it was pretty damn surprising...)

 

There is also a lot of research occurring in the area of pain e.g. research looking into selective sodium channel blockers that can be taken orally...

 

currently we only use local anasthetics (non-selective sodium channel blockers in injections or creams)...

 

but there are currently clinical trials carried out into selective sodium channel blockers (Nav1.7 and 1.8) that can be taken orally...

 

if effective clinically and side effects are low (as have been in animal models) - these drugs will be massive...

[Glider]

I think there needs to be some clarification on the difference between 'nociception' and 'pain'. Nociception refers to activity in the physiological mechanisms that have evolved to detect noxious and potentially harmful stimuli. However, "Activity induced in the nociceptor and nociceptive pathways by a noxious stimulus is not pain, which is always a psychological state, even though we may well appreciate that pain most often has a proximate physical cause.IASP

 

I would go further and say that the relationship between noxious stimulation (e.g. tissue damage) and pain is only correlational. This can be hard to accept because every time we stub a toe, or cut ourselves or whatever, we are provided with 'evidence' that tissue damage 'causes' pain. However, none of the predictions that are implicit in a causal relationship are true.

 

For example, if tissue damage (A) causes pain (B), then:

 

If A happens, B must always happen (not true).

 

B must always be preceeded by A (not true).

 

The same intensity of A presented to a person on repeated occasions will always result in the same intensity of B (not true).

 

The same intensity of A presented to two individuals will always result in the same intensity of B being experienced by each individual (not true).

 

So, whilst as a general rule, tissue damage will be 'painful', where there are so many exceptions to that rule, there cannot be said to be a causal relationship. The psychological state of 'pain' is associated with tissue damage.

[Edtharan]

So, whilst as a general rule, tissue damage will be 'painful', where there are so many exceptions to that rule, there cannot be said to be a causal relationship. The psychological state of 'pain' is associated with tissue damage.

As a sufferer of chronic pain I can fully aggree with this. I have a reoccuring injury (dislocaed sholder) which partically dislocates a couple of times a day (from a few milimetres to about 1.5 cm). Needless to say I am in constant pain.

 

I have learnt to control this pain by controling my focus. If I concentrate of the injury, then I am aware of the pain and it feels worse. But I can force my concentration elsewhere and I can reduce my awareness of the pain.

 

However, the Noxious stimulus (from the subluxations) are still there.

 

Noxious stimulus, from my experience, does not equal pain. But it is associated with it.

 

You can have pain without any noxious stimulus (phantom limb syndrome for example), and you can have noxious stimulus without pain (as I do when I avoid concentrating on my injury).

 

I would say that "Pain" is awareness of the noxious stimulus. But, we can have this awareness fooled by non-noxious stimulus, much as any sense can be fooled.

[Glider]

That's the crux of it, yes. Tissue damage will always result in activity in the nociceptive pathways, but that activity does not necessarily always result in pain.

[Revenged]

Chronic pain is different as a constant nociceptive stimulus can cause different levels of pain since the pain pathway can be both upregulated or downregulated...

 

Although psychological methods (i.e. distraction) can have a part in reducing pain - if you are in a lot of pain i doubt that thiss will work alone and you will have to take some sort of pain killer.

 

So why is it you can have different levels of pain for a constant pain stimulus?

 

You can have peripheral sensitisation - i.e. activation of sensory nerves (Ad and C fibres) causes these nerves to be more easily stimulated...

 

[i.e. if you cut yourself you have hyperalgesia in the surrounding area, even light touch in that area will be painful]

 

Peripheral sensitisation can also cause cental sensitisation - i.e. activation of NMDA receptors (wide up) in the spinal cord. This will increase the activity of the spinothalamic (pain) pathway.

 

However, this will be counteracted by downstream pathways.

 

Activiation of the limbic system changes neurotransmitter levels in the pain (e.g. serotonin and noradrenaline are particularly relavent in pain)... [edit: this can both up or downregulate pain... as a general rule serotonin tends to decrease pain + noradrenaline increases pain - this is why SSRIs are not a treatment for chronic pain whereas tricyclics are...]

 

It also causes release of other endogenous painkillers e.g. enkephalins (an engogenous opioids)...

 

You can increase this counteraction by drugs...

 

a) centrally acting pain killers - reduce central sentisation

 

Opiates (Codeine / Morphine / Diamorphine)

Low dose tricyclic antidepressants (e.g. amitriptylline)

NMDA antagonists (Ketamine - not really used for obvious reasons)

Ca2+ channels (Gabapentin)

 

or you can reduce inflammatory stimulus (note - not all pain states have an inflammatory cause so these not always effective)

 

b) Peripheral acting pain killers - anti-inflammatory agents

 

NSAIDs (ibuprofen / aspirin), Corticosteroids (hydrocortisol)...

 

For chronic pains you are probably prescribed a mixture of central and peripherally acting pain killers. i.e. co-codamol (coedine and paracetamol), co-dydramol, co-proximol (now withdrawn)...etc

 

But the majority of people feel better once the pain is removed simply by pain killers. With chronic pain the problem is different as side effects of the drugs may mean that taking the drugs for years is a bad idea (e.g. long term intake of opiates or steroids)

[Glider]

The difference is that Edtharan's pain is not strictly 'chronic' in the clinical sense. Whilst I don't doubt that it has persisted for a long time, it is more a long-term structural condition resulting in frequently recurring acute pain (i.e. repeated stimuli thoughout the day). There is a known organic cause, structural deformity and recurring soft tissue trama.

 

'True' chronic pain (i.e. the type chronic pain clinics are set up for) is more often idiopathic; neuralgias and myalgias and so-on. All of uncertain or unknown origin (i.e. no detectable organic cause). Chronic pain is a whole different animal and is much more strongly associated with affect and limbic function than direct nociceptive activity. Depression and chronic pain are very strongly correlated, but the direcction of any causal relationship could be either way.

[Revenged]

The difference is that Edtharan's pain is not strictly 'chronic' in the clinical sense. Whilst I don't doubt that it has persisted for a long time, it is more a long-term structural condition resulting in frequently recurring acute pain (i.e. repeated stimuli thoughout the day). There is a known organic cause, structural deformity and recurring soft tissue trama.

 

'True' chronic pain (i.e. the type chronic pain clinics are set up for) is more often idiopathic; neuralgias and myalgias and so-on. All of uncertain or unknown origin (i.e. no detectable organic cause). Chronic pain is a whole different animal and is much more strongly associated with affect and limbic function than direct nociceptive activity. Depression and chronic pain are very strongly correlated, but the direcction of any causal relationship could be either way.

 

I thought the clinical definition of chronic pain is pain lasting more than 6 months...

 

That include everything pretty much...

[Glider]

I thought the clinical definition of chronic pain is pain lasting more than 6 months...

 

That include everything pretty much...

That's true, but in Edtharan's case, it's not one 'single' pain that has persisted, it's repeated trauma to the same site.

 

I have a reoccuring injury (dislocated sholder) which partically dislocates a couple of times a day (from a few milimetres to about 1.5 cm). Needless to say I am in constant pain.

 

I hesitate to put words in Edtharan's mouth, but I would guess that the pain on dislocation is quite intense, but subsides in intensity until the next event. His condition (instability of the joint) is chronic, but the pain is acute, associated with each repeated trauma to the soft tissue of his shoulder, but the frequency of the repeating trauma won't allow the inflammation or associated pain to subside completely.

 

If the site was stabilised the inflammation would subside quite quickly, as would the associated pain.

[Edtharan]

That's true, but in Edtharan's case, it's not one 'single' pain that has persisted, it's repeated trauma to the same site.

The actual classification is a little difficult and some doctoers class it as Chronic Pain (as the pain has lasted for more than 6 months - going on nearly 8 years now - 1st of May will be 8 years), but because it has been caused by a repeated injury, some doctors call it a chroinic injury (although I don't think there is such a medical term).

 

I hesitate to put words in Edtharan's mouth, but I would guess that the pain on dislocation is quite intense,

Very intense .

 

It is why I will occasionally not post on here for several days sometimes, due to a particularly bad episode with my shoulder.

 

Because ofthe pain from the inflamation, I can uauall get around 10 minutes of typeing done before I need to take a break (around 1/2 hour with an ice pack) to bring the inflamation down.

 

but subsides in intensity until the next event.

Yes. However, as the pain never quite goes away (just from the sheer amount of tissue damage that has occurred through 6 opperations, and nearly 8 years of almost constant dislocations). The amount of constant pain I am in (when not in an accute phase) is roughly the same as having your arm twisted hard behind your back. I have learned to live with this level of constant pain through the methods I talked about earlier (distraction, etc).

 

Without consious awareness, this background pain is manageable.

 

However, when the subluxation occurs, then there are other signals that draw my attention to the injured site and it is much harder to avoid awareness of the pain, but I can control it in the same way (it just takes much more effort to avoid awareness of the stimulus).

 

If the site was stabilised the inflammation would subside quite quickly, as would the associated pain.

Yes. I can avoid using the shoulder (which is really difficult as it is the shouder of my dominent hand ) and reduce the inflamation, which does bring down the background levels of pain. But, it doesn't elimiate them as there is soft tissue damage, and possible some minor nerve damage that means that there will always be some pain.

[iNow]

So... Shall we all go now and dislocate the shoulders of a few non-human animals so can have evidence for or (more likely) against the OP?

 

 

 

<tongue fully lodged in my cheek>