TAMPA — Lying on her back with her feet in the sand, Dr. Amara Estrada tried to find the heart of the manatee lying above her.
Reaching under the custom-built table, she used an ultrasound sensor in her right hand and leaned forward to see the screen.
"You have to have some fairly decent ab strength (to do this)," said Estrada, a veterinary cardiologist with the University of Florida. "Once you got used to it, it was fine."
Few people have tried to look at a manatee's heart while it was still beating. Estrada worked with Dr. Trevor Gerlach, an aquatic animal health intern at UF and a veterinarian at Lowry Park Zoo, to see if echocardiography — an ultrasound technique used to look at the hearts of other animals — would work on manatees.
"We don't know anything about manatee hearts," Estrada said.
There's plenty of information on what a manatee eats, its anatomy and how it lives, Gerlach said, but very little research has been done on the health and wellness of manatees.
"It's more for knowing when a manatee is healthy enough to be released," Estrada said. "Maybe this should be part of their assessment."
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Gerlach said the new focus on manatee hearts started in 2011, when a 45-year-old manatee named Amanda was on her way back to the wild.
She had been rescued on Christmas Day in 1973 after being hit by a motorboat along Florida's southeastern coast. She had lived in Homosassa Springs Wildlife State Park for 25 years. Before she was to be released, however, Amanda had to undergo a biopsy for abnormal mammary swelling.
She was put under sedation, but never woke up. A necropsy showed she had underlying heart disease, and Gerlach said the drugs used to sedate manatees could have played a role in Amanda's death.
"A lot of drugs we use have effects on the heart," Gerlach said. "We don't have a ton of information on their health."
Gerlach had already worked at UF on a study that developed best practices for echocardiography in wolves, and an internship with UF's aquatic animal health program turned his attention to sea mammals.
Amanda's death, plus the lack of information on manatee heart health, led Gerlach to manatees.
"There was a need for it," he said.
Dr. Ray Ball, a veterinarian at Lowry Park Zoo who was involved with the initial trials of Gerlach's procedure, said that manatees coming in from cold shock and red tide are more likely to have clotting disorders — a problem that can be exacerbated by heart disease.
"That's another thing I'll add when assessing these animals," Ball said. "We can say, 'This manatee is dying of natural causes,' and that will change our treatment plan."
But how do you take an echocardiograph of a manatee's heart? You can't get in the water with the manatee, because the ultrasound equipment doesn't work underwater. You can't just put the manatee on solid ground, because their anatomy makes it impossible to get to the heart at that angle.
So Gerlach made some sketches, went to The Home Depot and talked to folks about the most structurally sound way to build a platform to support a 2,000-pound marine mammal.
The final product is made of pressure-treated wood and marine-grade polymer board. It's almost 10 inches high, 3 feet wide and 6 and 1/2 feet long. There's a foot-square hole right where the manatee's heart rests on the table.
That way, all Gerlach had to do was get the manatee onto the table, crawl underneath and try to find the heart on the ultrasound screen.
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It takes a team of 15 just to carry the manatee and conduct the research, and Gerlach said crowds of 100 to 200 people sometimes gather. It can be chaotic at times, but after nearly 50 captures, they have a solid protocol down.
A boat with a net works in a semicircle motion to herd manatees toward the beach. Then the manatee is put on a stretcher, then onto another boat, then taken to another beach, then onto the custom-made echocardiography table where the manatee is tested, then it's back to the water.
The process has to take less than an hour for the safety of the manatees, which stay awake the entire time, strapped down for the safety of the manatees and their handlers. That leaves less than 10 minutes for an echocardiograph. Most animals, such as horses and dogs, take 20 minutes – and that's on dry land.
"Cutting it down to 10 on an animal you've never looked at before is stressing," Gerlach said. "It's a big feat."
The ultrasound image is black and white – more shadow than light – and the technology makes it a little blurry, but the heart chambers are recognizable and the beating heart is visible. Researchers can measure the size of the heart and its valves and see how fast blood is moving through it.
"It is fun to see everyone's face when we get one up on the screen," he said. "It really was neat to see we could do this. We didn't think we could."
Initially, Gerlach says he was just looking to see if it could be done. Now researchers are trying to collect data to see if heart disease is common in manatees and if so, what can be done about it.
"There might be none," he said. "We just completed the first step. We're working on the second step and then we'll go from there."
Charles Scudder can be reached at [email protected] or (813) 225-3111.