Many marine mammals, one health

Environmental, human, animal health come together in San Diego
Published on March 20, 2013
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A dolphin undergoes a CT scan
A dolphin undergoes a CT scan at the Naval Medical Center. Capt. Lara S. Cotte said these procedures require working out a lot of logistics beforehand. (Courtesy of U.S. Navy Marine Mammal Program)

Marine mammal medicine—much like all of veterinary medicine—has changed a lot in the past 20 years because of better technology, a greater focus on specialty medicine, and an increasing emphasis on one health.

It’s the third development, however, that seems to have truly elevated the medicine practiced at the U.S. Navy Marine Mammal Program in San Diego. And it was born out of a necessity for expertise in a field in which not much is known.

“Some days, we’re doing procedures that have never been done before. That can be very rewarding and nerve-wracking. That’s why it’s nice to consult in the human and veterinary medical fields. You draw a lot of expertise in. So if you do a procedure that’s never been done before, you can put together a protocol that’s as safe as you can possibly put together,” said Dr. Eric D. Jensen, managing veterinarian for the program. “But there are days, though, when all of us would like to pull a book off the shelf and say, ‘Acute renal failure—how are we going to handle this in the dolphin?’ We can’t do that quite yet. There are new challenges almost on a daily basis.”

Hospital visit

The one-health concept became important to the program well before anyone knew to give it a name. Veterinarians would often consult with a wide range of specialists—from human oncologists to radiologists to infectious disease experts—at the Naval Medical Center in San Diego. Capt. Lara S. Cotte of the Army Veterinary Corps, officer in charge of clinical veterinary services for the program, said they have a good working relationship with interventional radiologists at the hospital, which allows them to perform ultrasound-guided biopsies and CT-guided bone marrow biopsies.

Before, the veterinarians didn’t have a good way to place a catheter in a dolphin to administer fluid support during a procedure, so they used the knowledge gained from the human medical field, she said.

Experts in surgery and medicine from the Navy hospital have also visited the program to help with particular needs. For instance, urologists assisted with the first ureteroscopy of a male dolphin.

The collaboration doesn’t stop with the hospital. Dr. Cynthia R. Smith, executive director for the National Marine Mammal Foundation, said the Navy program’s other major collaborators include the University of California-San Diego, University of Texas Southwestern Medical Center, Sea World, Dolphin Quest, and the Sarasota Dolphin Research Program, in addition to medical experts from various universities and hospitals around the country.

Translational research

If the Navy program’s plans are any indication, it appears further collaborations with human medicine are on the horizon.

Every five years, the program’s veterinarians sit down with invited guests to create a clinical investment strategy. The last meeting, held in June 2010, came up with the following:

  • Determine unique quality-of-life needs of aging animals.
  • Improve the detection, treatment, and prevention of infectious and metabolic diseases.
  • Apply advanced clinical technologies to better define population health baselines.
  • Provide protection against disease.
  • Apply one-health approach to research and medicine.

“We all thought it would be a great opportunity for us to learn more about what’s state-of-the-art in human medicine and pick and choose what to bring here and apply to this population of animals,” Dr. Jensen said.

Capt. Cotte applies local anesthetic
Typically, the U.S. Army Veterinary Corps works with the animals that deploy. Here, Capt. Lara S. Cotte applies local anesthetic during a dolphin procedure. (Courtesy of U.S. Navy Marine Mammal Program)

This partnership won’t be one-sided, though.

Dr. Stephanie Venn-Watson, director of the foundation’s One Health Medicine and Research Program, hopes to translate research findings into medicine advances that benefit both marine mammals and humans. As part of this effort, she is seeking partners and funding to research methods for better detection, prevention, and treatment of infectious diseases and diseases associated with diabetes and aging.

For example, she and Dr. Sam Ridgway have found that the best nonhuman model for type 2 diabetes mellitus may be a dolphin. While healthy dolphins naturally have sustained hyperglycemia after eating, they can also be susceptible to metabolic diseases and conditions associated with diabetes in humans, such as fatty liver disease, excess iron storage, and kidney stones.

In 2007, Drs. Venn-Watson and Ridgway, after reviewing seven years of routine blood samples from 52 dolphins, found that their blood chemistry values after food was withheld resembled values for people with diabetes—with elevated concentrations of glucose and other molecules—while their blood chemistry values after a meal were similar to those of healthy people.

Figuring out how dolphins turn their diabetes-like state on and off—and how this leads to problems—could reveal clues to preventing diabetes in humans, Drs. Venn-Watson and Ridgway believe.

Taking a look at your surroundings

In emphasizing the one-health approach, program veterinarians are also looking at how the environment may impact the Navy program’s animal population. The program has monitored total coliform counts in San Diego Bay for decades, Dr. Jensen said, but there’s still a lot they don’t know. A number of hazards exist, from runoff on the beaches to wildfires to pollution in the Tijuana River to sewage and oil spills.

Two swimming dolphins
The large brains of dolphins parallel those of humans, providing an opportunity to capitalize on the one-health approach. (Photo by Malinda Larkin)

Dr. Jensen said the Army Veterinary Corps officers with the program are tapping into their environmental resources and are reaching out to the Navy for help in deciding how and what information to collect.

The possibilities include testing fish, mussels, and plankton for domoic acid—a contaminant from blooming algae known to have toxic effects in marine mammals—and for metals, pesticides, and polychlorinated biphenyls. They may also look at the impact of native wildlife.

“We’re putting together what we hope will be a comprehensive and sustainable environmental health program for here in San Diego. When we get that up and running, we want to see how that will translate when we deploy. So, if we’re going to live somewhere for a month, how can we go on our site survey, look at the water and what might be running off the shores, the weather, and decide what impact, if any, it will have on animals and how we can mitigate that,” Dr. Jensen said.

He added, “It’s challenging. I’m not a toxicologist, and as we research and learn about it more, we realize it’s a really complicated area of health, so we’re really having to rely on finding experts and getting their opinions.”