Animals in Translation

by Temple Grandin

  Predator animals like dogs are less likely to mask their pain, but even they do it to some degree. Pain masking may be why a lot of vets will neuter a female dog and send her home without any painkiller. Any human who’s ever had abdominal surgery will tell you it’s agonizingly painful, but vets say that dogs sure don’t act like they’re feeling anywhere near as bad as a human does. We don’t know whether they’re masking their pain or whether they just don’t feel as much pain as we do in the first place. Either way it’s a problem, because animals need some pain to keep them quiet so they can recover. If dogs do mask surgical pain it’s especially dangerous, because a dog won’t spend any time alone if she can help it. A lot of vets will tell you they don’t like to give pain medication because they want your dog to have enough pain to slow it down for a while. That’s not a concern you’ll ever hear from a doctor who operates on humans.

  A friend of mine found this out the hard way. She had a young female Lab who was used to playing with three other young dogs. You put four very young dogs together, and you’ve got some wild and woolly play, which is what went on every day in my friend’s backyard. The Labrador had her surgery in the afternoon, then went home the same night. She was groggy and out of it, but the first thing she did when she got home was jump up on the sofa at the end of her owners’ bed and from there up onto the bed. No human being five hours out of abdominal surgery will jump onto a couch, ever. That’s something you just don’t see.

  So my friend and her husband gave the Lab doggie tranquilizers for a couple of days to keep her quiet, but she still played so vigorously with the other dogs that she didn’t heal properly. Instead of developing a thin red scar where the incision had been made, the surgical wound kept getting wider, turning into a concave area of shiny, moist tissue.

  Unfortunately, my friend didn’t know what the wound was supposed to look like and didn’t realize until almost too late that it wasn’t healing right. She was inspecting the wound every day to see if it looked infected, and while it didn’t look good to her, the incision didn’t look infected, either. She was getting more and more worried, but she thought she was just being an anxious owner.

  Finally she got so worried she took her dog back to the vet. He took one look at the dog’s belly and told my friend that if she hadn’t come in that day her dog’s intestines would have been “lying on the floor” by nighttime. There was no infection, but the skin tissue was completely broken down, and there was only a thin veneer of it left holding the viscera inside. My friend was horrified. You can see why vets worry about too little pain instead of too much. That Lab could have died from a routine spaying procedure all because she wasn’t showing any pain, so she didn’t slow down her social life with the other dogs for even one day.

  DO ANIMALS HURT?

  The short answer is yes. Animals feel pain. So do birds, and we now have pretty good evidence that fish feel pain, too.

  We know animals feel pain thanks both to behavioral observation and to some excellent research on animals’ use of painkillers. Starting with behavior, dogs, cats, rats, and horses all limp after they’ve hurt their legs, and they’ll avoid putting weight on the injured limb. That’s called pain guarding. They limit their use of the injured body part to guard it from further injury. Chickens who’ve just had their beaks trimmed peck much less, another obvious form of pain guarding. (Ranchers trim chickens’ beaks because chickens get in horrible fights and will peck each other to death. The vet trims off the sharp point so the chicken can’t use it as a knife blade.)

  We think insects probably don’t feel pain, by the way, because an insect will continue to walk on a damaged limb.

  Up until recently nobody knew whether fish felt pain or not, but two researchers in Scotland have shown that they almost certainly do. The study used electrical measurements of the brain backed up by behavioral observation. First they anesthetized some fish and applied painful stimuli like heat and mechanical pressure to their bodies while running a brain scan. They found neurons in the fish’s brains that fired in a pattern very close to pain firing in a human brain. Assuming this study can be replicated, it shows that fish have at least the sensory component of pain, though it doesn’t tell us whether the fish were actually feeling it consciously. Humans with certain kinds of brain damage can have the sensory component of pain without the “suffering” component, which I’ll get to in a moment.

  In the second part of the study, the researchers used behavioral observation to figure out what the fish were probably feeling. They injected either bee venom or vinegar into the fishes’ lips, which would be painful for humans and other mammals, and then watched to see what the fish did. The fish acted exactly the same way mammals act when they’re in pain. It took the fish an hour and a half longer to begin eating again than it did fish who’d had painless saline water injections, a classic sign of pain guarding. Their lips hurt, so they didn’t want to eat. They also showed other signs of pain. They rocked their bodies, something you see zoo animals do when they hurt, and they kept rubbing their lips against the side and bottom of the tank.

  These obvious behavioral changes are strong evidence that the fish were consciously experiencing pain, although the fish brain is so different from the mammalian brain that we can’t say for sure. Fish don’t have any neocortex at all, and most neuroscientists think you have to have a neocortex to be conscious. Still, the fact that a fish doesn’t have a neocortex doesn’t have to mean that a fish isn’t conscious of pain, because different species can use different brain structures and systems to handle the same functions.

  We have more evidence that animals feel pain from the experiments Francis C. Colpaert did on animals and pain medication in the early 1980s. He injected rats with bacteria that produce a temporary bout of arthritis we know is painful in humans, then gave them a choice between a bad-tasting liquid analgesic and a sweet, sugary-tasting liquid rats normally like. The rats chose the bad-tasting painkiller over the sugar solution, a pretty good sign they were choosing it for its painkilling properties. They definitely weren’t choosing it for its taste.1

  Once their arthritis cleared up they switched to the sugar drink, another sign they were using the painkiller to treat pain. If they’d been choosing the painkiller just because they liked it—maybe the same way humans can use painkillers as a recreational drug—they would have kept on using it after their arthritis cleared up. But they didn’t. When their joints were inflamed they chose a yucky-tasting painkiller; when their joints returned to normal they stopped choosing the yucky-tasting painkiller.

  Somebody needs to do Colpaert’s experiment with fish. That would tell us a lot.

  HOW MUCH DOES PAIN HURT?

  I think the real question isn’t whether or not animals (and birds and fish) feel pain. It’s pretty obvious they do.

  The real question is how much does pain hurt? Does an animal with the same injury as a person feel as bad as a person does? We should be talking about degrees.

  I think the answer to whether the same injury in an animal feels as bad as it does to a person is often no, for a couple of reasons. For one, even when they’re alone animals usually—not always, but usually—act as if an injury or disease hurts them less than the exact same injury or disease would hurt a person. That’s important.

  Beyond that, a lot of what we know about the brain leads me to think animals may have a different experience of pain than people do. I remember being struck a year or so ago when I came across a study saying that chronic pain is associated with widely spread prefrontal hyperactivity.2 That surprised me. Pain seems like such a basic sensation I’d just naturally thought of it as a primitive reaction all creatures have to have to protect themselves from injury. To me, pain seemed like an ancient, lower-down brain function. Since the frontal lobes are as high up as you can get, I wasn’t expecting to read that pain is associated with high frontal lobe activity. That study made me wonder whether an animal’s conscious pain may be less intense than a person’s, be
cause an animal’s frontal lobes are smaller and less developed.

  When I started looking into the literature on frontal lobes and pain I found out that psychiatrists have known about this connection for years. The idea that active frontal lobes mean active pain was so well established that in the 1940s and 1950s a few psychiatrists began treating cases of severe and intractable chronic pain by surgically disconnecting the patient’s frontal lobes from the rest of his brain. The operation they did was called a leucotomy, and basically it was a less-invasive lobotomy. Where a lobotomy removed the frontal lobes completely, a leucotomy left the frontal lobes in place but cut the connections between the frontal lobes and the rest of the brain.

  Both operations had a lot of horrible side effects, but the positive effect on a pain patient’s suffering was almost miraculous. A couple of days after the operation patients who’d been completely disabled by pain would be up and about, doing the things they used to do. The “recoveries” were so dramatic that Antonio Egas Moniz, who invented the operation, won the Nobel Prize for his work in 1949.3

  I put “recovery” in quotation marks because leucotomy patients didn’t exactly recover. They acted like they’d recovered, but whenever people asked how they felt, they’d always say the pain was still there. What was different after surgery wasn’t the pain; it was their feelings about the pain. They didn’t care about it anymore. Antonio Damasio has a description of one of these patients in his book Descartes’ Error.4 The first time Dr. Damasio saw him, the patient was in such bad shape he was “crouched in profound suffering, almost immobile, afraid of triggering further pain.” Two days after the operation the man was sitting in a chair, playing cards with another patient. He looked completely relaxed.

  When Dr. Damasio asked the patient how he was doing his answer was, “Oh, the pains are the same, but I feel fine now, thank you.” You can read story after story exactly like that one in the literature on leucotomy and pain. After their operations, leucotomy patients stopped caring about their pain. Dr. Damasio says they kept their pain but lost their suffering.

  It’s impossible to imagine what it would feel like to have severe pain but not be bothered by it, because for the rest of us severe pain means severe suffering, period. They aren’t two different things. I’m sure that’s because our frontal lobes integrate sensory pain pathways so totally with frontal, emotional pathways of suffering that we can’t perceive any separation at all. It’s a little like stereoscopic vision: if your vision is working right you can’t separate what your right eye is seeing from what your left eye is seeing without closing one eye.

  Even though we can’t feel what the leucotomy patients were feeling, it seems like they were still feeling something like what we would call pain, because they still asked for painkillers. On the other hand, after the operation they stopped asking for really strong painkillers like morphine. All they needed was aspirin. It’s possible they were feeling something similar to what the rest of us feel when we have pain mild enough to ignore. Mild pain is still pain, but it doesn’t ruin your life, whereas severe pain hijacks your attention system. That’s almost the definition of severe pain, that it commands all of a person’s attention.

  Another piece of evidence the leucotomy pain patients were still feeling “real” pain, at least to some degree, is that if you suddenly poked one of these patients with a pin they would shriek in pain. They would actually shriek louder than a normal person with normal pain perception. Most researchers chalk this up not to greater pain but to lower impulse control. The frontal lobes censor and control outbursts of any kind, including screams of pain. Since these patients had lost their mental brakes, they screamed at a mild poke.

  I think injured animals are probably somewhere in between a leucotomy patient and a normal human being. They do feel pain, sometimes intense pain, because their frontal lobes haven’t been surgically separated from the rest of their brains. But they probably aren’t as upset about pain as a human being would be in the same situation, because their frontal lobes aren’t as big or all-powerful as a human’s. That’s why they don’t slow down after surgery the way we do. They don’t feel bad enough to slow down. I think it’s possible that animals may have as much pain as people do, but less suffering.

  AUTISM AND PAIN

  A lot of autistic people are the same way, which is another reason I tend to think animal pain is less severe than human pain on average. As I’ve mentioned more than once, whenever I come across a difference between animals and normal people that involves the frontal lobes, I’ve usually found the same difference in autistic people. We have a lot in common with animals. So I’m expecting to find the same thing with pain perception.

  Just like animals, quite a few autistic people—not all, but many—act like they feel less pain than nonautistic people. This happens so often that insensitivity to pain is listed on most symptom checklists for autism. It’s especially shocking with little kids who are self-injurious. Some of them can slap their heads hard with their hands and not seem to feel any pain at all (other autistic children slap their heads and then cry). There’ve even been reports of autistic children burning their hands on hot stoves and not reacting, although fortunately that’s extremely rare. Autistic children don’t have such low pain sensitivity that they’re in danger of injuring themselves without knowing it.

  Another interesting thing: a lot of parents tell me their autistic children don’t have normal sensitivity to cold, either. They can spend hours in the deep end of a freezing cold swimming pool while all the other kids just splash around for a few minutes and then go warm up on the deck. I don’t know whether animals have lower cold sensitivity on the whole. Animals in northern climates do better in winter cold than people do, but they have nice fur coats to keep them warm and people don’t. A wolf’s coat is so thick snow doesn’t melt on its body.

  So I have no way of knowing how cold perception compares between animals and people with autism. Also, I want to make sure I’m not implying to parents or teachers or anybody else that autistic people are impervious to everything that comes their way. The autistic sensory system is abnormal for a person, while an animal’s sensory system is normal for an animal, so I don’t know where the similarities begin and end. I do know that while some things are less painful for autistic people than for typical people, other things, especially certain types of sounds, are more painful. I remember one autistic woman saying she found the sound of the ocean excruciating. (There might even be stimuli that are more dangerous for people with autism, though we don’t know that. A few years ago I talked to a woman involved in autism research who said she was concerned that some autistic people might be more susceptible to heat stroke. I’d never heard that before, and she based her comment on just a couple of families, so I don’t want parents to start worrying about it. I bring it up because I don’t want to minimize the discomfort an autistic person could be feeling.)

  I don’t remember how I reacted to pain as a child, but as an adult I’ve been told that I’m a lot less sensitive to pain than nonautistic people. When I was “spayed” (I had a full hysterectomy, medically the exact same procedure as spaying a dog, that left an eight-inch scar across my stomach) I acted more like my friend’s Lab than a post-surgical human being. The nurses said I didn’t use anywhere near the amount of IV painkiller other patients did. Then when I went home, I took one prescription pain pill and that was it. I didn’t need any more.

  In the hospital I ran a little experiment on myself. When I was sure the nurses weren’t around, I got out of bed and got down on all fours like a dog. The staff would have had a fit if they’d seen me. I found out that as long as I held still my pain was a lot less than it was standing up or sitting down. Crawling felt terrible, but not as bad as walking did. Still, even on all fours I didn’t feel like jumping up on a sofa, so obviously I’m not as impervious to pain as a Labrador retriever. Then again, no dog is as impervious to pain as a Labrador retriever, either. Labs are notorious for their h
igh pain threshold, which is one of the reasons they make such good pets for children. A little kid can jump all over them and maul them half to death and they feel nothing. (Not that I’d recommend any child being allowed to do that. It’s bad manners, and with other breeds it could be dangerous.) Try stepping on any normal dog’s paw and you get an ear-splitting yelp so loud that for a moment you think you’ve killed your pet. Step on a Lab’s paw and he doesn’t even blink. Labs are built for racing through bramble and brush to retrieve game, or jumping into freezing cold water to retrieve fish. Nothing fazes them.

  Back to my experiment, it’s possible there’s something about being a four-legged creature instead of a two-legged creature that makes the pain of physical injuries less intense. But even if that turns out to be true, I expect it’s going to be only part of the explanation for why animals act as if they have less pain than we do for the same injury. Eventually we’ll find out that the real explanation for the difference in behavior is a difference inside the brain.

  FEAR IS WORSE THAN PAIN

  A lot of effort has been put into creating humane slaughter systems so the animal doesn’t suffer. That part was easy, relatively speaking. If all you had to do to eliminate suffering was to make sure the animal died instantly, today almost all of our slaughterhouses would have to be considered humane.

  But eliminating pain isn’t enough. We have to think about animals’ emotional lives, not just their physical lives. We’re responsible for slaughterhouse animals; they wouldn’t even exist if it weren’t for us. So we have to do more than just take away physical pain.

  The single worst thing you can do to an animal emotionally is to make it feel afraid. Fear is so bad for animals I think it’s worse than pain. I always get surprised looks when I say this. If you gave most people a choice between intense pain and intense fear, they’d probably pick fear.