Connecting Human & Animal Health with Dr. Barbara Natterson Horowitz
Dr. Barbara Natterson Horowitz
Jonathan: Hey, everyone. Jonathan Bailor, back with another bonus Smarter Science of Slim podcast. Folks, today’s show – I have to tell you, this is pretty cool. This is a subject that’s all about living better and just cutting-edge science that can help us live better lives. We have a guest, a brilliant researcher, professor, author, speaker – just superwoman of sorts – who has done some research. I’ve literally never seen anything like this before and it is just cool stuff!
She has been a cardiologist for over 20 years at the UCLA Medical Center – so no ‘woowoo’ here. She is a professor of medicine in the David Geffen School of Medicine. She is also doing all kinds of stuff with the Los Angeles Zoo. She recently wrote this amazing book, that we’re going to talk about today, called ‘Zoobiquity’. I’m going to let her describe what she does because it is literally amazing! Dr. Barbara Natterson-Horowitz, welcome to the show!
Dr. Natterson: Oh, I’m so happy to be here.
Jonathan: Well, Dr. Natterson, your new book – ‘Zoobiquity’ – it covers something like a species-spanning approach to medicine that I have never heard of before. Can you tell us a little bit more about this?
Dr. Barbara Natterson-Horowitz Cardiologist
Dr. Natterson: Sure. Well, I am a cardiologist. I have spent a couple of decades taking care of people with high blood pressure and heart attacks and cholesterol issues. But then, several years ago, I had this wonderful opportunity to go to our local zoo, the Los Angeles Zoo, and assist some of the veterinarians with some of their cardiac imaging issues. Although zoos around North America are staffed by incredibly qualified vets who know how to brilliantly take care of their patients, from time to time, they will call on colleagues from the human side to come and participate in the care of the animals, and I was one of these lucky physicians.
So I started hanging out with the vets and, I have to say, until that point, the only time I ever really encountered veterinarians was when I was taking my own animals in for vaccinations or minor issues. So here I was, listening to these veterinary doctors talking about breast cancer in lions and obsessive-compulsive disorder in polar bears and diabetes in kangaroos and on and on, and it occurred to me that, here I had spent over 20 years taking care of these same problems in my human patients and I simply had never thought about the world of veterinarians and their patients who were dealing with the same issues. So that’s how this whole thing started with this opportunity to visit with the vets in my local zoo.
Jonathan: Dr. Natterson, let me pop out to why this is, I think, so cool and, in some ways, a whole new field of medicine – which gets me really excited. I’m a science geek. I love reading studies. I have read many, many of them and we know the importance of animal models and studying and animal models, because we can do things in animal models that we can’t do in human models. Plus, there’s also when you use a mouse and you study eating patterns, there is not as much emotional eating and societal influences. We can just look at the mammalian behavior. But you’ve actually seen that maybe if researchers previously thought, “Okay, there is the way humans act and think and they have this emotional side. Then, there are animals and they are totally different.” You’ve actually found some amazing parallels, haven’t you?
Dr. Natterson: Exactly. The surprising aspect of this whole project was asking the questions ‘Do animals ___?’ and assuming the answer would be ‘no’ because I assumed certain behaviors had to be uniquely human.
Let’s talk about eating behaviors. One of the questions that my co-author, Kathryn Bowers, and I asked was, “Do animals ever get fat? Do they ever become clinically, medically obese?” We also asked, “Could an animal get an eating disorder? Do animals ever self-induce vomiting, for example? Or would animals ever engage in secret eating or the hoarding of food or other disorders that psychiatrists would consider pathological on the human side?” It turned out that the answer to each of these questions was ‘yes’. Not only do these behaviors happen in animals, very often the animal experts have very interesting and effective approaches for dealing with these problems.
So, just to start with the ‘Do animals get fat?’ question, ‘Do they become obese?’ Animals, particularly companion animals, are getting, unfortunately, fatter and fatter. Many are overweight. Probably about 50% of our dogs and cats are overweight and about 40% or so are actually obese. It’s such a significant issue that there’s a diet pill, for example, that is now indicated for obese dogs. There are dogs that have actually undergone liposuction. There is a diet that is recommended for some obese felines which is a very high-protein, low-carbohydrate diet that they, of course, call the ‘Catkins diet’. Yeah, it’s incredible! There are actually some zoo veterinarians who, several years ago, began putting some of the animals under their care on a kind of Weight Watcher’s point system-type approach and it goes on and on.
Perhaps it’s not that surprising that companion animals are getting fatter. I mean, they’re under our supervision. We under-exercise and overfeed them and don’t give them the right kinds of food, perhaps just as we don’t do that for ourselves, but it was interesting in our research to learn about even some wild animals who also seem to be getting fatter.
When we talked to some ecologists and wildlife biologists, who have spotted this trend in certain populations – we’re talking about some marmots, some rats, some marine mammals – they have some hypotheses that there could be environmental effects, whether these are endocrine-destructing chemicals in the environment, antibiotics, or other issues that could be contributing to this.
The other really interesting and unexpected area that we found similarities in was the issue of eating disorders – of actual eating behavior. Before doing this book, if you’d asked me, “Do any animals other than human beings overeat?” I think I probably would’ve said no. I would’ve assumed that wild animals, for example, had these internal, self-regulatory mechanisms that led to them never eating beyond satiety. Well, it turned out that that’s completely wrong.
We met with some veterinary nutritionists who had worked in the wild who said that, in fact, almost all wild animals, if given access to abundance, will actually over-consume. From an evolutionary perspective, that makes sense. In nature, periods of abundance are almost always juxtaposed with periods of scarcity and so the drive to over-consume really makes sense. Knowing that, it kind of, in a way, helped me better understand my human patients who struggle with over-consumption. In a way, it allowed me to think of it in a…. Not to normalize it in the sense that it’s okay to do, from a health perspective, but to understand it in a broader context.
The other really interesting and unexpected eating behavior that we learned about was the incidence of something called regurgitation and reingestion, which is seen in Great Apes like gorillas and chimpanzees and some marine mammals like beluga whales and dolphins, and this is a behavior where animals, typically when they’re encountering social stress, will actually induce emesis. They’ll induce regurgitation. They’ll make themselves vomit. They do this repetitively. Sometimes they will re-consume the matter that they have vomited and then vomit again. So they’re engaging in a kind of compulsive regurgitation syndrome that seems to be done to soothe them because it happens during periods of social stress.
Those kinds of parallels were eye-opening for me and have allowed me to think about human eating disorders like food hoarding, anorexia nervosa, bulimia nervosa, et cetera. from a much broader perspective.
Jonathan: Dr. Natterson, you mentioned that three things are related. One is that obesity, overweight and animals seem very closely tied to the domestication of animals, meaning that dogs and cats, things we have as pets, having them as pets, a.k.a. domesticating them, seems to correlate very strongly with these obesity and related conditions. Also, even if not domesticated, if their environment – their natural environment – is somehow de-natured, a.k.a. it’s not really their natural environment anymore because it is being interfered with by human-induced toxins or something along the likes – it’s been adulterated in some way, they also experience these diseases typical of civilized humans. Am I understanding that correctly?
Dr. Natterson: Yeah. Unfortunately, our cats and dogs are encountering the same sad collection of medical problems associated with obesity that we have. From diabetes and hypertension, all of these are happening as a consequence of over-consumption. One of the things to think about, though, is that in the wild, animals’ weights vary; that is normal and that is expected. When there is abundance, animals over-consume and then when there’s scarcity, their body weight goes down. That variation is normal and speaks to sort of the cyclical nature of what happens in the outside world.
I’m not sure exactly how that applies to the human case, but I think it is interesting that mammalian metabolism evolved in a setting in which the environment kept shifting and that it’s likely that up until very, very recently, even the human body weight shifted based on the seasons. So that is interesting because typically, as a physician, I don’t like to see big shifts in my patients’ weights. The ideal is to have a patient be at an optimal weight where their blood pressure is normal, where they’re happy and comfortable, and their lipids are outstanding. That’s what we like to see. We don’t like to see kind of a waxing and waning. But in fact, in nature, it’s very different.
Jonathan: Sorry, so what did you see or what did you observe? Certainly there are seasonal climates, but there are also Mediterranean-type climates or climates near the equator, tropical climates where an animal that eats nothing but plants, seems to have access to unlimited amounts of plants all year round, yet they do not become morbidly obese. What’s taking place in that animal?
Dr. Natterson: Well, I can’t answer for sure. I can just share with you some of the ideas that the research has sparked. Based on what we learned from these veterinarian nutritionists, the desire to over-consume is there, but animals, in the wild at least, their eating is regulated by, in part, danger. So, predatory threat becomes a significant factor in how often animals will feed versus hide, when they’ll come out.
In fact, in environments where predators have been called – and one example of that was in Yellowstone when the wolves were removed many years ago – the elk began grazing more hours per day, they got heavier, there was a shift in their body morphology. So my suspicion would be that wild animals who live in settings of constant abundance don’t ultimately over-consume because there is a constraint imposed by predation risks that they encounter daily.
Jonathan: It’s fascinating, Dr. Natterson, because there seems to be a bit of a dichotomy in the research. I know there was a big struggle, at least in mice and rats, prior to the advent of the cafeteria diet. Trying to fatten these experimental animals just by giving them more rat food was difficult. They would literally try to pump rats full of food into their stomach and the rats would just stop consuming food voluntarily to avoid chronic obesity. So I’m curious if you have any insight into that?
Dr. Natterson: I can’t answer that question, other than to say that I think there’s no constant, there’s no one answer, and species are as varied as they are. We know a tiny little bit about this whole question of appetite and metabolic regulation. I mean, it’s exciting to be at the beginning of this, but what I’m sure about is taking a comparative approach. That is, look at metabolism, hunger, satiety across species, can generate new hypotheses. One of the problems is, as physicians, we only look at homosapiens and that’s been limiting us.
Jonathan: I love that, I love that. The reason I’m digging on this one area, for lack of better terms, is there has obviously been this big push, it seems, and a lot of success by homosapiens to say, “If you just eat things that homosapiens ate historically – not processed garbage, but rather things you could find in nature – the natural diet for humans, it becomes very difficult. There are tens of hundreds of thousands of people who will tell you it’s very hard to over-consume non-starchy vegetables and nutrient-dense protein, like it hurts before you would eat too many calories.
Dr. Natterson: Yeah, I think that’s a really good point. That’s a great point, yeah.
Jonathan: I am just curious because it’s almost like one of the things you would learn from the animal kingdom potentially, is the more something becomes divorced from its evolutionary context, it seems things tend to go downhill when that happens.
Dr. Natterson: Oh, yeah. You can look at a lot of diseases from the perspective of a mismatch between the environment in which we evolved and what we encounter today. There is an emerging field called evolutionary medicine which is looking explicitly at this issue – how to understand why we get sick. Mmuch of the time, the reason we get sick is that we’ve created environments – built environments, biological environments – that are very different from the way we’ve evolved.
Jonathan: What are the most compelling hints you’ve seen from the animal kingdom, especially maybe our close ancestors like apes and such, where ‘if they are put in these social contexts or if they’re given these cues, things get better for them.’ What are some promising areas there?
Dr. Natterson: I think a couple of areas, which is kind of a low-hanging fruit, is the behavioral stuff. When vets encounter animals who are getting fatter and are unhealthy, particularly animals who, let’s say, are in captivity or perhaps are under our care and in a variety of situations, you can’t talk to an overweight bear, let’s say, or an overweight monkey or whatever about showing more willpower or making better food choices. That’s impossible. But what you can do is you can modify their environment. They do something called environmental enrichment.
They will make the enclosure – this is in zoos, for example – more complicated. They will make it challenging for the animal to access their foods. They have toys that are called environmentally-enriched toys and they’ll put the food in difficult-to-find places. What they’re effectively doing is they’re making it harder, more interesting, actually more intellectually challenging, to access the food versus strapping on a feed bag and just letting them feed at will.
It’s funny. As I was learning about all the ways that vets deal with animal obesity through modifying the environment, environment enrichment, it began affecting how I was shopping for food for my own family and thinking about how I accessed food. I have always been pretty interested in nutrition and kind of eating whole foods and whatnot, but I haven’t spent a lot of time thinking about how a longer prep time could probably lead to me consuming a little bit less of what I didn’t need and a longer prep time could probably be more gratifying for my family if we all participated in it. So it actually started influencing me a little bit.
What vets do with environmental enrichment is very powerful. They’re able to treat veterinary anxiety, animal anxiety, which is a very significant problem for dogs and cats, and they’re able to treat compulsive disorders, particularly canine compulsive disorder, with modification of the environment. They deal with bullying that way. So that’s one of the interventions that I think there’s a lot of promise for and I’ve actually encouraged our Department of Psychiatry here to consider sending the residents in Psychiatry to spend time, maybe a week or so, with a veterinary behaviorist to learn how they do it with animals that can’t use language to communicate what they’re feeling and what’s working.
Jonathan: Obviously, there seems to be much to learn here. On some level, especially we’ve shown the genetic similarities between certain species of apes and humans. I mean, we have the ‘animal’ part of our brain. Obviously, you’re the expert here. Is that what we are seeing patterns? Like, ‘the amygdala works this way in mammals’ kind of. Is that what we’re seeing or…?
Dr. Natterson: Yeah. I think there’s a lot more that’s conserved than that’s different and that’s been the big light bulb. If you ask most physicians about it, they’ll agree with you almost instantly, but we don’t think that way. We tend to think these issues are uniquely human. So when I first started learning, for example, about post-traumatic stress disorder in dogs and anxiety disorder… By the way, I have to tell you that I’m a very skeptical person. My co-author and I approached this entire topic, particularly of animal psychiatry, with tremendous skepticism. Neither of us knew much about it, but I became convinced that, in fact, absolutely animals can suffer from anxiety disorders, they absolutely can suffer from a canine form of obsessive-compulsive disorder, and actually the gene for canine compulsive disorder has now been identified by Nick Dodman at Tufts. So these things that we might – that I, let’s say – used to assume were uniquely human, were not.
As you begin realizing that they happen in a very similar way in non-human animals, you then have to look at the conserved biology that, yes, it’s shared neurochemistry. It’s that fear and anxiety are ancient. Mammals have been on Earth for about two hundred million years, but we know from veterinarians who specialize in reptiles that even reptiles, snakes and lizards, can develop what they call an emotional tachycardia. Tachycardia is the medical term for an accelerated heart rate. They can develop an emotional fever when they are scared, when they’re handled too much. So, in fact, even something like anxiety is even older than two hundred million years. These emotions, and that would include, my guess, is the relationship between fear, anxiety, food, resources – all these responses are shared by many animals with whom we shared common ancestors literally hundreds of millions of years ago.
Jonathan: So, we’re seeing the overlap of human medicine and evolutionary biology and veterinary medicine – what gets you most excited about the confluence of those three disciplines?
Dr. Natterson: At UCLA, we’ve just started a program in evolutionary medicine. The chairman of evolutionary biology, Dan Blumstein, and I are really excited that UCLA undergraduates can now minor in evolutionary medicine. We’re starting our first cycle of courses this year and I’ve been putting together lectures. I started by just drawing a timeline of disease. So it’s literally like one of those timelines everybody looked at in school where you have the present on the far right and way, way, way past on the left. As I began looking leftward, I was able to put diseases.
Paleontologists have found evidence of cancer, for example, in the bones of dinosaurs, so I put, at about a hundred million years ago, cancer. There’s evidence of diabetes in hoofed animals and members of the order Carnivora, so I’m able to write diabetes at least sixty million years ago. Gout, arthritis, stress fractures also seen in dinosaurs – able to add that to the list, and so on and so forth. So this idea that these disorders that I’ve been taking care of since I became a doctor have actually existed in long-deceased animals, but their ancestors still bear these genes. So these disorders are not only not uniquely human, they are not unique to our contemporary times. That, for me, is a mind-blower.
Jonathan: I love it, I love it. Well, what’s next for you, Dr. Natterson? What’s next for you, the Zoobiquity movement, UCLA – what’s going on in the future?
Dr. Natterson: Right. We have been putting together these conferences to bring together veterinarians and physicians to talk about the shared diseases of their different patients. At past conferences, we’ve looked at obesity, we’ve looked at bullying, we’ve looked at self-injury, cutting – because, of course, animals self-injure unfortunately in response to stress, just as some humans do.
Our next conference, we’re most excited about, is going to be in New York on November 2, and it’s going to be jointly sponsored by the Wildlife Conservation Society of New York, which oversees the zoos and aquariums in New York and does a lot of international outreach for wild animals, and the Animal Medical Center, a very prominent longstanding provider of veterinary services in New York City and UCLA.
We are going to have truly the leaders in human and veterinary medicine. We have the Deans of vet schools, we have Dr. Harvey Fineberg, who is the President of the Institute of Medicine, coming on the human side. In the morning, this group of 300 physicians and veterinarians are going to be discussing breast cancer in, I think we have a beluga whale case on the animal side and a cat case on the animal side and we have a couple of human cases – women with breast cancer.
We’re going to be discussing anxiety disorders. We’re going to be looking at eating disorders across species in the morning.
Then at noon, this entire group is going to get on buses and we’re going to all go to the Bronx Zoo, which is wonderful. I think it is the oldest zoo in the United States. We’re going to be going on WalkRounds led by the very prominent veterinarians there at the Bronx Zoo. So it should be a wonderful day. Any physicians, veterinarians, even nurses, psychotherapists who are interested in these connections between the disorders of humans and animals should look into it. It’s going to be a great day.
Jonathan: Dr. Natterson, that sounds very, very, very fascinating. Just as fascinating as your wonderful book which, again, folks, is called ‘Zoobiquity – What Animals Can Teach Us About Health and the Science of Healing’. You can learn more about that book as well as our wonderful guest, Dr. Barbara Natterson-Horowitz, over at zoobiquity.com. Dr. Natterson, thank you so much for sharing your time and this very interesting research with us today.
Dr. Natterson: Oh, Jonathan, it’s been a pleasure! Thank you so much.
Jonathan: Listeners, I hope you enjoyed this conversation as much as I did. Please remember, this week and every week after – eat smarter, exercise smarter, and live better. Chat with you soon.