Zoobiquity

  ‡Imagine one and a half packed 747s crashing every day and you’ll appreciate the public health significance of the problem.

  §Many things can cause VF and VT and sudden cardiac death. Some dangerous heart rhythms are inborn, such as long QT syndrome. Others are acquired: electrolyte disturbances, viral infections, antibiotics and other drugs, and aortic ruptures can all result in fatal arrhythmias. Even acts of God, like being struck by lightning, a high-velocity karate chop, or a Little League line drive to the chest that falls at precisely the wrong moment, can cause the heart’s valvular structures to vibrate violently and then stop moving (doctors call this commotio cordis).

  ‖Like the on-set veterinarians who allow film studios to declare, “No animals were harmed in the making of this movie,” Mulcahy is an on-site veterinarian in the field, monitoring animal safety for field biologists observing and tracking wildlife. Working for the United States Geological Survey, Mulcahy has pioneered and enforces protocols to make these studies safer for the animal subjects.

  aVeterinarians divide capture myopathy into four classic presentations: “capture shock syndrome,” “ruptured-muscle syndrome,” “ataxic myoglobinuric syndrome,” and “delayed peracute syndrome.” These terms describe various physical manifestations of the syndrome, ranging from weak muscles and unsteady gait to kidney failure and sudden death. A captured wild animal may exhibit one or more of these syndromes during chase and/or capture.

  bThese are all examples of animals in the wild, but stress before being slaughtered in broiler hens, sows, steers, and lambs damages their muscles, too. The same muscles, when wrapped in plastic on a Styrofoam tray, are sold as meat. Some farmers recognize this and (perhaps for the wrong reasons) strive toward less-stressful slaughter techniques.

  cIn long QT syndrome, abnormalities in ion-channel function cause the period between waves of heart activity to lengthen dangerously. This condition predisposes the patient to a potentially fatal cardiac arrhythmia. Long QT can be inherited (many of the genes have now been identified) or acquired. Many common medications, including some antibiotics, antidepressants, and antihistamines, can bring on long QT episodes. So can some electrolyte disturbances like severe vomiting and diarrhea.

  Tellingly, startling patients who have a long QT can actually kill them. The emotional jolt can trigger an extra beat, which leads to a deadly arrhythmia. And that type of jolt can be caused by sudden loud noises, anger, arguing.… or fear.

  dSudden unexpected noctural death syndrome (SUNDS), for example, largely afflicts young men from the Hmong ethnic group of Laos who die in their sleep. Hmong are wary of a very specific nightmare (dab tsog) in which a terrifying evil spirit appears and actually “kills” the dreamer. This effect probably involves an underlying (possibly genetic) electrical problem with the heart. But it needs the cataclysmic (catecholamine-inducing) stress of the nightmare—which takes its imagery from firmly established folklore traditions—to kill. Young Filipino men have also been reported to die from something similar, called bangungut (Tagalog for “to rise and moan during sleep”). There is a reason this may sound familiar to current or former horror movie fans. It is the premise of the Nightmare on Elm Street movie franchise, in which teenagers who are pursued and killed in their dreams by the movie’s villain, Freddy Krueger, die in real life.

  eSometimes the thing that’s supposed to protect you accidentally kills you. An example of this phenomenon is demonstrated in some human-engineered systems. Take air bags. To be effective lifesavers in the split seconds after impact, these scorchproof polyester pillows must deploy at velocities exceeding two hundred miles per hour. Not surprisingly, although tens of thousands of lives have been saved by air bags since their 1997 introduction, thousands of people have died when the force of rapidly opening air bags ruptured hearts, tore pulmonary arteries, and cracked neck vertebrae. This happened mostly to babies and young children riding in the front seat, before legislation made that illegal.

  fSome cases of SIDS may stem from overlapping neurological, respiratory, and cardiovascular syndromes. One emerging theory connects SIDS to abnormal brain function leading to improper sensing of rising carbon dioxide levels, called hypercapnia.

  SEVEN

  Fat Planet

  Why Animals Get Fat and How They Get Thin

  I never, in all my years of counting calories, expected to receive dieting advice from a grizzly bear. But there I was, in a dark conference room with about a hundred zoo veterinarians, raptly listening to a presentation on how Jim and Axhi, two obese Alaskan grizzlies at Chicago’s Brookfield Zoo, had dropped hundreds of pounds.

  Delivering the secret was Jennifer Watts, Brookfield’s easygoing, bespectacled nutritionist, a Ph.D. who oversees the diets of the animals at the zoo. Projected on a screen next to her was a “before” photo. It was just like my favorite moment on every TV makeover show—seconds before the “reveal.” The “before” bears’ shimmying bellies barely cleared the ground. Rolling billows of flesh rippled along their flanks. Years of overfeeding had ballooned their faces and erased all memory of their necks.

  Then Watts flashed the “after” picture. A few chuckles escaped from the animal doctors around me. The difference was huge. Svelte and glossy, the bears simply looked healthier. If they’d been my patients, I’d be breathing easier, too, knowing that, along with their weight, their risk of obesity-related health problems had just plummeted.

  Although I’m a cardiologist, some days I feel more like a nutritionist. Patients, family, and friends all frequently ask me, “What should I be eating?” We all know by now that choosing the wrong foods and carrying extra weight on our bodies can make us sick. Obesity, weight gain, “eating right”: these concerns are at the very core of modern preventative medicine.

  And yet, listening to Watts talk about the grizzly bears, I realized something that was at once astounding and obvious: humans aren’t the only animals on our planet who get fat. And it turns out that it’s not just iconic fatties like hippos and walruses who pack on the pounds. Animals as varied as birds, reptiles, fish, and even insects regularly gain—and then take off—weight. And they do it without ordering dressing on the side or going on slimming crusades involving shots, pills, psychotherapy, and even surgery. Fattening in the animal world has enormous potential lessons for humans—including dieters looking to shed a few pounds and doctors grappling with obesity, one of the most serious and devastating health challenges of our time.

  But until that moment it had simply never occurred to me to wonder, Do animals get fat?

  As you’ve probably heard many times, we are in the midst of an “obesity epidemic.” Millions must cope with this life-threatening disorder. Doctors everywhere are urgently searching for a cure.

  What may surprise you about this obesity epidemic, however, is that I’m not talking about overweight humans (not yet, anyway). There’s another obesity epidemic going on around us. It afflicts our dogs and cats, horses, birds, and fish. Domestic animals around the world are fatter than ever before, and steadily gaining more weight.

  Exact numbers are hard to pin down—in part because pet owners and veterinarians don’t always recognize when a beloved Lab or tabby has crossed the line from well fed to positively plump. But studies in both the United States and Australia put the number of overweight and obese dogs and cats somewhere between 25 and 40 percent. (For the time being, animals are still doing better than we are—the proportion of U.S. human adults who are now either overweight or obese is close to a jaw-dropping 70 percent.)

  With our pets’ excess pounds have come a familiar suite of obesity-related ailments: diabetes, cardiovascular problems, musculoskeletal disorders, glucose intolerance, some cancers, and, possibly, high blood pressure. They’re familiar because we see nearly identical problems in obese human patients. And just as in our population, these weight-related diseases among dogs and cats often lead to premature death.

  The efforts to combat excess animal girth will also sound fam
iliar. Some dogs are put on diet drugs to curb their appetites. Liposuction has been the treatment of choice for some severely obese canines when the extra flab threatened to snap their spines or splay their hips. Companion felines have been placed on the “Catkins” diet—a veterinary version of the popular high-protein, ultra-low-carb Atkins diet for humans. Veterinarians increasingly treat “portly ponies.” They instruct owners not to overfeed chubby fish. They suggest giving husky lizards more exercise to work off their surplus weight. They describe tortoises so fat they can no longer pop in and out of their shells. They’ve seen so many overweight birds they have a new nickname for them: perch potatoes.

  Exotic animals in nonwild settings are getting rounder, too. Concerned about the health effects of extra flab, zoo veterinarians in North America and Europe have placed overweight animals from flamingos to baboons on slimming diets. Many of these regimens borrow strategies from human weight-loss programs. If you’ve ever tallied daily Weight Watchers points, you understand the routine of the gorillas and cockatoos at Brookfield Zoo, where Jennifer Watts has put the animals on a similar system. In Indianapolis, zookeepers have encouraged rotund polar bears to move around their enclosures by tempting them with calorie-free, artificially sweetened gelatin treats in place of the sugary marshmallows and molasses of yore. In Toledo, plump giraffes have been offered biscuits that are specially formulated with lower salt and higher fiber, in place of the junk crackers they had been getting.

  What all these corpulent animals share, what sets them apart from their wild cousins and ancestors, is one thing. We feed them. They are mostly or completely dependent on humans for every meal, and we regulate both the quality and the quantity of everything that passes their lips and beaks. Consequently, we can’t really blame them for their weight problems. Of course, a dog will eat pretty much whatever you put in front of her, and still sniff around for more. The very idea of a cat exercising willpower to resist a fattening treat seems ridiculous. And so we’re left with one conclusion: we, the species that both manipulates food to make it more unhealthful and has the intelligence to understand that we shouldn’t eat so much of it, are to blame. We’re responsible not only for our own expanding waistlines but for those of our animal charges as well.

  And even just living around us humans can make animals balloon. City rats crawling the alleys in urban Baltimore, for example, grew about 6 percent fatter, per decade, between 1948 and 2006, presumably because their food came almost entirely from human garbage cans and pantries. These rats also showed about a 20 percent increase in the chance of becoming obese. But our fattening leftovers might not have been the sole cause of the rodents’ increase in body weight. The researchers who studied these urban rodents found an intriguing parallel weight gain in another group of animals. The city rats’ country cousins also became fatter—at nearly the same rates—during some of that same time period. And even though their food supplies were more “natural,” rats in the parklands and agricultural areas around Baltimore also showed an increase in the odds they would become obese.

  It’s pleasing to assume that when animals are in their native environments, eating what they “should” (the unprocessed foods they evolved with), they will stay effortlessly lean and healthy. But that’s not necessarily true. I’d long imagined that, in the wild, animals will eat until they are full and then stop. In fact, given the chance, many wild fish, reptiles, birds, and mammals will overindulge. Sometimes spectacularly so—even on wholesome, natural foods. Abundance plus access—the twin downfalls of many a human dieter—can challenge wild animals, too.

  Although we may think of food in the wild as hard to come by, at certain times of the year and under certain conditions, the supply may be unlimited. Seeds spill across fields. Larvae cover sand and vegetation. Eggs lie easily available under every leaf. Bushes fill with berries. Flowers ooze with nectar. And when animals’ environments are this abundant, they will gorge. Many stop only when their digestive tracts literally cannot take any more. Tamarin monkeys have been seen to eat so many berries in one sitting that their intestines get overwhelmed and they soon excrete the same whole fruits they recently gobbled down. After gorging on abundant prey, carnivorous fish sometimes start excreting undigested flesh. Big felines, like lions, as a matter of course stuff themselves after a hunt until they can barely move. Mark Edwards is an animal nutrition expert at Cal Poly, San Luis Obispo, and was the first nutritionist at the San Diego Zoo and Wild Animal Park. As he told me, “We’re all hardwired to consume resources in excess of daily requirements. I can’t think of a species that doesn’t.” In fact, when presented with unlimited food, domestic species, including dogs, cats, sheep, horses, pigs, and cattle, eat nine to twelve meals per day.

  With ready access to superabundance, some wild animals have become impressively fat. A seal with the catchy nickname of C-265 was recently euthanized by the Oregon Department of Fish and Wildlife. His crime: bingeing on more than his share of endangered chinook salmon during the annual run. So enthusiastically did C-265 feast on the lox smorgasbord that he nearly doubled his weight in just two and a half months (going from 556 to 1,043 pounds). His appetite was undeterred by the firecrackers and rubber bullets deployed by rangers to protect the precious salmon stocks. And C-265 was not alone in his gluttony. Dozens of seals have been euthanized since a federal judge’s controversial 2008 ruling allowing eighty-five of them to be killed each year to protect salmon reserves.

  The weight of blue whales off the California coast fluctuates from year to year, depending on the population of krill, their favorite food. Some years, they’re so skinny the individual vertebrae protrude noticeably from their backs. Other years, as a whale-watching boat captain described it to me, they’re “fat, happy, and relaxed.” And who can forget the undulating, pendulous, black-and-white bellies in the movie March of the Penguins, belonging to birds that could barely waddle after gorging for weeks in the ocean?

  In the Colorado Rockies, warmer temperatures since the 1960s have correlated with a body change for yellow-bellied marmots. As Daniel Blumstein, chair of the UCLA Department of Ecology and Evolutionary Biology, explained to me, “As the snow has melted earlier over the past forty years, marmots have emerged from hibernation sooner, had a longer growing season, and entered hibernation in better condition, which increases both survival and reproductive success.” In other words, marmots have gotten fatter. A study Blumstein copublished in Nature with biologists from Imperial College London and the University of Kansas showed that across generations of marmots, average weights have swelled by more than 10 percent over the nearly five decades of the research period. If this doesn’t seem like a lot, consider that CDC data show that over the same five decades, average adult male weights in the United States have also increased by about 10 percent (from about 166 pounds in 1960 to about 186 pounds in 2002). This trend tracks with the human obesity epidemic, although the implications may be different. Says Blumstein: “The marmot population has tripled in the past decade. Chubby marmots are happy marmots.”

  Slovakians living at the base of the Carpathian Mountains once believed that their local lake contained a unique species of wild carp—bigger and meatier than the fish found in nearby waterways. But upon closer inspection, it turned out that the impressive specimens were Esox lucius—exactly the same species as the smaller fish. A flood had swept nutrients off nearby farms into the lake, providing the piscine gluttons with so much extra food that their bodies had swelled beyond recognition. This ability to get hugely fat when there’s extra food around is shared by fish in many other regions.

  So wild animals can get fat the same way humans do: in environments with unfettered access to abundant food. Of course, animals also fatten normally—and healthily—in response to seasonal and life cycles (and more on that in a moment). But what’s key is that an animal’s weight can fluctuate depending on the landscape around it.

  A zoobiquitous approach gave me a more nuanced appreciation of why and how animals g
et fat. It reminded me that weight is not just a static number on a chart. Rather, it’s a dynamic, ever-changing reaction to a huge variety of external and internal processes ranging from the cosmic to the microscopic.

  This echoes something I heard a wise colleague say: “Obesity is a disease of the environment.” Richard Jackson is the chair of Environmental Health Sciences at UCLA and a former head of the National Center for Environmental Health at the CDC. In an impassioned Internet video recorded in 2010, he explained what he meant:

  One of the problems with the obesity epidemic is we too often blame the victim. And yes, every one of us ought to have more self-control and ought to exert more willpower. But when everyone begins to develop the same set of symptoms, it’s not something in their mind, it’s something in our environment that is changing our health. And what’s changing in our environment is that we have made dangerous food, sugar-laden food, high-fat food, high-salt food … and we’ve made it absolutely the easiest thing to buy, the cheapest thing to buy, and yes, it tastes good, but it’s not what we should be eating.

  This point is similar to one made by David Kessler, the former head of the U.S. Food and Drug Administration, who pointed the finger at processed foods in his 2009 book, The End of Overeating. Excess sugar, fat, and salt, Kessler argued, “hijack” brains and bodies and drive cycles of appetite and desire that make it nearly impossible to resist certain fattening foods. Essentially, even if we can resist one package of chips or plate of cookies, our “environment” now comprises endless mountains of these foods everywhere we look.

  And these fattening landscapes present themselves to animals, who then overconsume. Even some animals you’d think would know better.