The Hippo with Toothache (31 page)

Given their long plane flight and the two days they'd spent in a dark, sealed bag, I fully expected to find one or both of the dragons acting sluggish or looking thin. These are common signs of mild stress due to shipping, since fish are not fed during transport and are in a confined space.

At worst, if the concentration of dissolved oxygen in the
water had dropped more than it should have, or if a considerable level of nitrogen (the waste product of fish) had accumulated, I wouldn't have been surprised if the dragons had a high gilling rate. This sign of stress is equivalent to breathing fast. By rapidly opening and closing their gills, which are supplied by a dense network of capillaries, fish can take in more oxygen and also get rid of waste products that build up in the bloodstream.

Alex, one of our biologists, held the lid of the box open while I took my first look at the dragons. Just as he'd warned, they were floating at the surface and struggling to stay upright. I watched them for several minutes, thinking about what to do next. For whatever reason, they couldn't keep their bodies beneath the water's surface. This species of sea dragon has a long snout, and the gills sit right behind the angle of the jaw. Neither of the new dragons could keep its snout or gills under the water. They were piping, or gasping—not for air, but for water. This was a life-threatening situation. No vertebrate animal can survive without oxygen. Something must have gone wrong during the shipment, or perhaps the box hadn't been properly prepared to begin with.

I quickly directed Alex to take a sample of the shipment water to the water quality lab. He'd been instrumental in helping me get the animals to Florida, following up on every detail to make certain everything went smoothly. He looked just as worried about the dragons as I was. We tested for temperature, nitrogen waste product levels such as ammonia and nitrite, dissolved oxygen saturation, salinity, and pH. The results were normal.

If the problem wasn't in the water, it had to be inside the patients. Dragons, like many other types of fish, have air bladders (also called gas or swim bladders). This organ helps them with buoyancy control, so that they can maintain their position in the water. Maybe their air bladders had become overinflated during transport. Even worse, they might have ruptured, allowing free air into their body cavities. This excess air, whether inside the bladder or outside, would make it impossible for the fish to swim beneath the surface of the water.

I ran through the possible reasons for an overinflated air bladder. Changes in air pressure during the flight could cause this; maybe the cargo hold hadn't been properly pressurized. The lower pressure could result in gas leaving the bloodstream and forming gas bubbles in the tissues of the fish. Another possibility was that the box had been exposed to excessively low temperatures, which could have affected the concentration of oxygen and other gases in the water and bloodstream, increasing the amount of gas released into the air bladder, and then expanding when temperatures warmed up again. Or, and this last possibility was at the top of my rule-out list, the water in the sealed transport bag had been supersaturated with oxygen gas during some part of their trip.

If you've ever purchased a pet fish for your home aquarium, you may have seen the salesperson tie the plastic bag so that it puffs out with air, like a half-filled water balloon. The oxygen in the air will help keep the oxygen levels in the water at a healthy level. When fish are transported long distances, pressurized oxygen gas is added to the container to ensure that oxygen levels remain high inside the bag for
several days. But if the dragons' sealed bag was inadvertently overpressurized, the gas pressure inside the air space, and thus the water, would have been initially too high, exposing the dragons to excessive, harmful gas pressures.

It was going to be difficult, if not impossible, to find out for certain what had happened to the dragons during transport, and it wouldn't necessarily change the treatment options. Time was of the essence. My priority was to confirm the diagnosis even if I couldn't be certain of the root cause. The game plan was simple: radiograph the animals to look for overinflated air bladders.

Since the dragons were small and relatively inactive, they didn't need anesthesia for radiography. We could position them on the X-ray film cassettes the way we do other small fish, take the picture quickly, and replace them in the water. Gently I picked up the first patient, wearing powderless latex gloves to minimize damage to its skin and protective mucus, and placed it on its side directly onto the cassette. Susan, my veterinary technician, positioned the X-ray beam, lined everything up, and set the machine. She got ready to hit the exposure button while I darted behind the lead screen. Seconds later, I ran back into the room to return the dragon to the water. We repeated the procedure for our second patient.

After developing the film, we could see that the body cavity of one dragon was completely filled with air. In the other, we saw the outline of an overinflated air bladder, which was most likely compressing the intestines directly below the bladder.

There might appear to be a simple solution to this life-threatening
problem: place a needle into the air bladder and withdraw the excess air. But in a sea dragon, such a procedure can result in the introduction of infections or in laceration of other internal organs. To complicate matters further, the dragons' thick scales, like a coat of bony armor, make it difficult to insert a needle through the skin without squashing the fish.

I had another idea: treat the fish as you would a human. Put them in a high-pressure chamber that gradually moves the trapped gas out of the wrong places. Maybe we could take them to a dive chamber and treat them as if they had the bends, a common complication of scuba diving. Florida is a popular diving destination, and I knew there were several recompression chambers nearby.

This thinking was based on what we know about fish anatomy. The air bladder is normally filled with various gases, oxygen being one of them, thanks to a system known as countercurrent exchange. The oxygen gets there via a complex bed of arterial and venous capillaries known as the rete mirabile (Latin for “wonderful net”). The capillaries are arranged in such a manner that blood rich in oxygen flows past blood low in oxygen; the gas then moves from areas of high to low concentration. The exchange takes place near the wall of the air bladder, so it can deflate or inflate depending on the concentration of the gases passing by in the blood vessels. By exposing the dragons to high pressure, simulating a dive, maybe we could drive the gas back out of the bladder and into the bloodstream.

Fish also use countercurrent exchange to breathe. The arrangement of capillaries in the gills is not as elaborate as in
the swim bladder rete, but the overall result is the same. The gas moves from high to low concentration, from the water into the bloodstream and then to the tissues. This is, of course, why our floating dragons were in big trouble. Their overinflated air bladders prevented them from keeping their gills underwater. If we could get the gas out of the air bladder and into the bloodstream, maybe it could leave via the gills.

Though we humans don't have an air bladder, the gases in our bloodstream are subject to the same rules of physics. They move in and out according to pressure as well as chemical differences. The bends, also known as decompression sickness, occurs when scuba divers ascend too quickly. The air in their tanks has been compressed under pressure, ensuring that oxygen is delivered to the tissue as they dive down. As long as the diver ascends slowly, these gases will leave the body as the pressure equalizes. However, if the diver rises to the surface too fast, the gases will expand and form bubbles in blood vessels and tissues, which can cause painful tissue damage or even death. Trapped gas in the wrong place is a medical emergency—in any species.

I decided to go for it. It sounded like a weird plan, taking tiny fish that look like seaweed into a hospital recompression chamber, but why not give it a try? I knew that our local hospital, St. Joseph's, had such a chamber. In addition to treating dive accidents, it's used in the treatment of several human diseases, including diabetes. People with this disease have very poor circulation in their feet and hands, and the increased chamber pressure helps improve oxygenation.

For people with the bends, the chamber pressure forces
gas bubbles in the tissues to dissolve and go back into the bloodstream, where the gas would then be slowly released out through the lungs. In the case of the sea dragons, I hoped for the same thing: the pressure would compress the excess gas out of the air bladder and allow it to be absorbed back into the bloodstream, and out of the body through the gills.

When I called the hospital, the officials responded to my odd request by giving us an appointment for the next morning. Because running the chamber is time-consuming and expensive, they requested that the dragons share the chamber with several human patients. Grateful for the offer, and knowing the dragons couldn't survive for much longer, I accepted.

In order to keep the animals from staying at the surface overnight, we placed them in the container we'd prepared for their arrival. Using a plastic grate, we gently pushed the dragons down into the water and left the grate in place so that they would remain several inches under the surface.

The next morning, Alex filled a portable acrylic tank with about twenty gallons of water and set it in a shallow Styrofoam container to which we added ice. We wanted the water temperature in the tank to stay relatively cool, around 60° Fahrenheit. He added an air stone attached to a small portable compressed air tank that would keep the water oxygenated. Carefully I slipped the animals into the tank and, with the help of Alex and three other biologists, slowly lifted the “travel package” into a van.

An entourage of officials and public relations personnel met us at the hospital. Dragon paparazzi!! The local press wanted to film the event because it was so unusual; also
because it helped highlight the fact that many of the procedures used in human medicine can be applicable to animals (in fact, many are first developed using animals).

We set the tank and accessories on a cart and wheeled it down the hall to the chamber room. The chamber itself looked like a large steel bank vault, with pressurized windows on the sides, and several chairs. There were lots of curious looks as well as a few chuckles from the hospital staff and the human patients who were waiting for the procedure to start. Maybe the sea creatures would help make a long, boring procedure a bit more exciting for everyone. After the people had taken their places in the chamber, I walked in with the tank that held the dragons and set it near one of the windows so Alex and I could watch the procedure.

The hatch was closed, locked, and sealed to deal with the pressure changes, and the process began. The pressure in the chamber would slowly increase, simulating a sixty-foot dive. The two animals in the acrylic tank gradually began to sink toward the bottom—precisely as we had hoped. There were a few thumbs-up gestures from the patients in the chamber.
Phew
, I thought,
maybe we can save these little guys after all
.

For the next few hours, there was nothing for us to do but wait and hope the capillary beds inside the sea dragons could do their jobs. As we waited, we talked with hospital staff and the patients' relatives about aquatic animal medicine. They were amazed at what was possible. We explained that we routinely take fish radiographs, perform surgery, and treat a range of different animals, from corals to sharks. We even use many of the same antibiotics and other drugs used in
people. The range of success, however, is variable: aquatic medicine is still a new frontier in veterinary medicine.

When time was up, we watched anxiously as the pressure in the chamber was slowly reduced. At about thirty feet, the sea dragons gradually moved upward, but not all the way. Holding my own breath, I hoped they would hold their positions. But as soon as the pressure returned to room conditions, the animals were back on the surface, struggling once more to stay upright. The procedure had not worked.

Back at the aquarium, I went through all of the possible causes of the dragons' problem and alternate treatments. After making a few phone calls and checking the literature again, I had no new ideas. I desperately wanted to save these special creatures, and not just because of all the time and effort (and money) we'd put into bringing them to Florida. With their arrival, our aquarium had joined a partnership known as Project Seahorse, an organization designed to call attention to the endangered status of sea dragons as well as sea horses.

Before being shipped halfway across the world, our pair of dragons had been nurtured and fed in a special setting. We'd worked with an experienced collector in Australia who holds one of very few permits issued by the government to collect a limited number of specimens per year. These permits are given to discourage illegal collecting of adult dragons. Fishermen catch them not for food but as sources of “alternative” types of human medicine or as souvenir trinkets for sale in countless numbers of curio stores. It's sad to think of these animals ending up in such shops. They are so beautiful in life.

The collector is permitted to collect two types of dragons: one male weedy sea dragon, like the ones we received, and ten male leafy sea dragons. In aquarium lingo, we call them the “weedies” and the “leafies.” Sounds a bit like sports teams. The weedies have fewer appendages but tend to be more colorful, with yellows, blues, reds, and lots of decorative white spots. The leafies are the kings of camouflage, with ornate yellow and green fronds that blend in so perfectly with underwater vegetation that they can be hard to spot even when they hover right in front of you.

Like sea horses, sea dragon males carry the eggs, though they are attached to their tails rather than inside pouches, and they can carry up to 250 eggs each. The wild fish are kept in a holding facility until they give birth, and then released back to the wild. When the eggs hatch, the young dragons, only about a quarter of an inch long at birth and practically transparent, are maintained in optimal water conditions, free of predators, and fed several tasty meals a day—sort of an aquatic bed-and-breakfast arrangement. Once they grow to about four inches in length, they are ready to be shipped. This complicated step requires all kinds of permits and paperwork, special containers, and logistical arrangements to ensure the shortest flight routes and times.