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Vets Give Lab Animals a Little Love

June 2013–Eric Hutchinson assumed he would become a journalist or, maybe, an English professor. Instead, after completing his undergraduate degree, he wound up building monkey bars — for monkeys. Today, Hutchinson is still working with research animals, now as an assistant professor at the Johns Hopkins University School of Medicine’s Comparative Medicine Laboratory.

Hutchinson’s divergence from liberal arts began with an undergraduate course in animal behavior, through which he visited a field station run by the National Institutes of Health. That station housed an enormous paddock full of monkeys used as control animals in scientific experiments. The monkeys’ living space was designed to keep them happy and healthy. Intrigued by the science behind crafting such living spaces, Hutchinson began interning at the NIH over the summers, and after graduation, the NIH hired him to build enriching environments for research animals. Hutchinson stayed on for another three years and then went on to complete his doctorate in veterinary medicine (D.V.M.).  

Anyone with a D.V.M. can enter private practice immediately after graduation, but those interested in research must continue their schooling. Unlike most graduates, Hutchinson knew going into vet school that he wanted to work with research animals, instead of Fido and Fluffy. “Lab animal medicine is very exciting,” he says. “You’re the first one trying to set a tracheal tube in a marmoset.”

So Hutchinson entered a residency program at Johns Hopkins. The school offers two tracks: a three-year residency program for vets who want to care for lab animals and a four-year postdoctoral fellowship for vets interested in conducting their own research. Entering students specialize in lab animal medicine or pathology.

In their first year at Johns Hopkins, all students complete a rotation in lab animal care or diagnostic pathology. Students who, like Hutchinson, continue along that track can expect to spend their time helping researchers figure out which animal models to use, ensuring that the basic needs of research animals are met, performing medical procedures necessary to the research, and training animals for behavioral studies. In many ways, vets that care for animals are akin to the stage crew in a dramatic production: behind the scenes yet crucial to the success of the show.

Veterinarians interested in conducting their own research can simultaneously work with a research team at the school and complete a Ph.D. — a twist on the established doctorate to postdoctorate route. With most translational research taking place in animal models, many students following this track say that getting a D.V.M. in place of a medical degree makes sense. For instance, Rachael Cohen, a first-year postdoctoral trainee in laboratory animal medicine, has just started looking into possible research projects. Many diseases affect more than one species, says Cohen, so understanding the unique progression of the disease in different species can provide crucial insight into the disease’s mode of action.

Kelly A. Metcalf Pate’s research into simian immunodeficiency virus, the monkey equivalent of human immunodeficiency virus, or HIV, is a case in point. Despite major advances in understanding HIV since it was first discovered in the 1980s, the disease has no broadly available cure and afflicts some 500,000 people in the United States alone. SIV gives researchers a way to test ideas and possible cures in animals.  

As a postdoctoral fellow in laboratory animal medicine at Johns Hopkins, Pate began studying a complication of HIV that causes a central nervous system disease similar to dementia. That complication arises when monocytes, an essential immune responder in the blood, enter the brain. Pate’s Ph.D. thesis demonstrated that platelets, another immune responder, and monocytes interact at the earliest stages of infection. Now, as an instructor in molecular and comparative pathobiology at Johns Hopkins’ school of medicine, Pate is investigating how platelets affect monocyte behavior. Specifically, she is trying to find out whether monocytes bound to platelets are more likely to become infected by SIV and enter tissues. Pate suspects that infected monocytes that bind to platelets are more likely to enter new places in the body. She hopes this research will make it possible to block the virus before it enters the brain.

One of the highlights of training and working as a veterinarian at Johns Hopkins, Pate says, is a strong culture of collaboration among researchers with different specialties. “Almost every project we undertake to better the situation or health of the lab animals involves the teamwork of a veterinarian-clinician, a veterinarian-researcher and a veterinarian-pathologist,” she says.

Those who follow the pathology track focus, by definition, on the recently deceased. Sarah Beck, a fifth-year student in the pathology postdoctoral training program who is on the verge of completing her Ph.D., says that during her early years of training, she spent the majority of her time performing diagnostic necropsies. Though working primarily with Johns Hopkins research animals, she also investigated the deaths of animals in local animal hospitals and the SPCA, the National Aquarium in Baltimore, and the Maryland Zoo in Baltimore. These days, Beck is much more focused on her research investigating whether or not the animal being used for research affects a virus’s ability to survive and replicate.  

Despite following different paths after the first year of training, lab animal care and research aren’t always mutually exclusive. Just six months into his residency, Hutchinson began tending to a colony of marmosets, monkeys with distinctive white tufts of hair emanating from their ears. Marmosets elicit complex calls that researchers use to study hearing. But the marmosets in Hutchinson’s care started to lose weight. They didn’t have diarrhea and they weren’t vomiting. Their appetites, moreover, were insatiable. “It was really kind of weird,” Hutchinson says. Slowly, Hutchinson got more and more caught up in the riddle. He helped locate a biomarker — high albumin levels — that characterizes animals that will acquire the wasting disease. Because training the animals for the experiment can take up to a year, the ability to weed out marmosets destined to fall ill saved considerable time and money.
Yet Hutchinson still wants to know the cause of the disease and what he can do to eliminate it. Hutchinson is starting to suspect that the process of turning the animals into models for research could itself be the culprit — a huge source of frustration for researchers who just want a functional animal model. “For every new experiment, there's a new way that an animal can get sick,” he says. Luckily vets like Hutchinson are obsessed with sorting it out. The marmosets, Hutchinson says, have become “the Moby Dick to my Ahab.”

–Sujata Gupta