The choice to spend high school and college summers in biology labs studying the intricacies of canine diabetes is not for everyone.
But for Emily Shields, 23, now a second-year graduate student in genomics and computational biology at Penn's Perelman School of Medicine, that decision was easy.
"I always knew I wanted to go into science," says the West Caldwell, N.J., native over an outdoor lunch on the Penn campus. "In ninth-grade biology, we had an assignment to look at pond scum and there was this roly-poly wormlike thing wriggling around under the microscope and I remember thinking - this is the coolest thing ever.
"I know it's a cheesy story." She grins. "But that was it for me."
The result? According to her mentor, Jake Kushner, formerly of Penn and now chief of pediatric diabetes and endocrinology at Baylor School of Medicine, Shields' high school and college lab work at Penn and Baylor contributed important insights for a newly published paper.
The study, published in PLOS ONE, quantifies the loss of insulin-producing beta cells in dogs with the disease and compares it with those of people with type 1 diabetes. Kushner was senior author on the paper.
"There's a twofold value to this paper," said Shields. "It better explains diabetes in dogs. People care a lot about their pets; they go to great lengths to care for them. Secondly, it might be a new frontier to study type 1 diabetes [in humans] and further our understanding of the disease."
With Shields leading the research team, investigators employed advanced imaging techniques to examine pancreatic tissue from 23 dogs with diabetes and 17 without the disease. The pancreas contains islet cells, which in turn contain insulin-producing beta cells. Insulin is necessary for turning sugars into fuel for the body.
The study showed that, like humans with type 1 diabetes, dogs develop diabetes after a dramatic loss of beta cells. Without enough beta cells, the pancreas can't produce enough insulin, which must be replaced through injections.
Unlike humans, who tend to develop type 1 diabetes in childhood, dogs develop it later in life. The study found that humans have about half the number of beta cells in their islets compared with dogs. This might explain why canine diabetes starts later, as they may need to lose more beta cells before symptoms begin.
"Another surprise was that dogs we studied had very few islets left and only a few beta cells," said Kushner. "Humans often have some residual islets. It suggests that some really aggressive process is destroying these cells."
The researchers had hoped to find evidence that, like type 1 diabetes, canine diabetes was an autoimmune disease. But, said Kushner, they found no "smoking gun" that showed inflammation or an autoimmune attack on the islet cells in dogs.
Kushner said they might have been looking at samples in which it was too late in the course of the disease to see that response.
"What we think is that dogs have diabetes for many years but it's clinically unapparent," said Kushner.
By the time symptoms are evident and canine diabetes can be diagnosed, dogs have lost the ability to manufacture insulin.
"I would love to know why the disease develops in a dog," said Rebecka Hess, professor of internal medicine at Penn's School of Veterinary Medicine and an author of the study. "If we improve our understanding of how the disease develops, we can intervene earlier to help with treatment and prevention."
Certain breeds have a higher risk of diabetes, including Samoyeds, miniature schnauzers, miniature and toy poodles, pugs, and Australian terriers.
The good news is that with insulin injections, said Hess, dogs rarely die of diabetes.
The next step in the research is to establish biomarkers that might help identify animals prone to diabetes before it strikes, and to look earlier for evidence of an autoimmune process at work.
Shields started work on the canine diabetes project after graduating from high school, during the summer before she attended Tufts University. The paper was written - and rewritten - during her first semester at graduate school.
Kushner found Shields' enthusiasm and hard work during the project amazing.
"She took this project on entirely on her own," he said. "She was just relentless."
Shields says science is "just hard work."
"The desire to figure something out that no one else knows," she says. "That's what drives us all."
Do those moments make all the hard work worth it? Emily gathers the remains of her lunch and her book bag, ready to head back to her grad school studies.
"I think so," she says. "I think so."