Animal Health Q&A: Dolphin Care
The field of marine mammal veterinary science is constantly evolving, and we've received some great questions from our community over the last few months about how we care for our dolphins.
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We sat down with Dr. Scott Gearhart, Clinical Veterinarian for the National Marine Mammal Foundation and Dr. Leigh Clayton, National Aquarium for details.
From a veterinary perspective, the most obvious challenge is that dolphins are a large, powerful species that's exclusively aquatic. This limits our ability to easily provide the most common therapeutic method we use in almost all other species—intravenous (IV) fluids, which is the fastest way to deliver medicine and fluid replacement through an animal's body. Lacking IV fluids as a treatment option makes it challenging to correct and manage hydration when animals are feeling very ill and don't want to eat. Additionally, other common treatment options are much more challenging, such as abdominal surgery. Dolphins consciously breathe—they need to actually "think" about it in a way humans and other mammals do not—making general anesthesia more challenging than in other mammals.
The most unique part of a dolphin's anatomy would be their respiratory tract and stomach. The naris (blowhole/nose) is on top of the head. The stomach has three chambers, connected through very small tubes. Our field has yet to find a way to visualize or take samples from the third stomach chamber or small intestines—both mainstays of diagnosing disease in humans and pets like dogs and cats.
Staff are the first line of defense when it comes to detecting potential illnesses in dolphins. They often see extremely subtle changes in behavior and body language that can indicate early illness and are quick to notice if a dolphin appears to be a little "off."; The dolphin may hold their body or swim slightly differently—arching slightly, swimming more slowly, appearing tense—or their eyes may be squinted. Just like us, dolphins also have typical ways of interacting with each other and their surrounding environment. Staff may notice a change in how the dolphin is interacting with others in their pod or how they're spending time with enrichment and staff. Some animals may interact more with staff when they feel ill, while others may withdraw. Dolphins will generally not want to eat as much or as readily when they're not feeling well. Other signs of illness might be vomiting, diarrhea and/or lethargy.
We look for how their current blood values may be different from their historical blood values and from reports of normal ranges in other populations of animals. We are looking for what values appear to be within normal limits and what values are outside a likely normal range.
A routine diagnostic workup for an animal that isn't feeling well often includes a physical examination, blood collection, fecal and stomach fluid collection and an exhaled "chuff"; (blowhole) analysis. For the most part, these are obtained with voluntary cooperation of the animal, since husbandry behaviors are one of the foundational skills. Ultrasound examinations of the abdomen and thorax are also routinely completed.
Results of these diagnostics tests usually provide valuable clues to the state of the dolphin's health. Elevated white blood cell counts are routinely seen in dolphins with bacterial or fungal infections, just as you'll see in dogs, cats and humans. We'll also look to see how fast red blood cells settle at the bottom of a test tube—a process known as erythrocyte sedimentation—or if fibrinogen levels—a type of protein—are increased. Both tests can indicate inflammation or infection in the blood. Fecal, gastric and chuff samples may also show evidence of abnormal bacterial populations or inflammation.
Dolphin digestive systems are structured to most efficiently serve their aquatic environment—one that might see them needing to take advantage of variable feeding opportunities and prey abundance. The first chamber or forestomach is the largest of the compartments and can distend and stretch easily. It serves as a receiving chamber for food items. The second chamber—also called the glandular chamber—is responsible for secreting the digestive enzymes which break down the food. Lastly, the pyloric compartment functions to regulate passage of digested food into the small intestines.
The liver in animals has a wide variety of functions. A major function of the liver is to help digest and process nutrients from food. For example, the liver makes bile, which is sent to the small intestine to help with digestion and absorption of fats and fat-soluble vitamins. Blood from the intestine goes to the liver. Nutrients are taken from the small intestine to the liver and can be sent to the rest of the body or processed for storage. The liver also has a major role in making proteins needed for a variety of functions in the body, such as blood clotting. These are just some of the functions the liver performs.
We take a wide variety of factors into account when developing a treatment plan for each dolphin. Some of the major factors include how sick we think the dolphin might be, how quickly we think the dolphin might get better or worse, the personality and behavior history of the dolphin, the physical facility we have, and the social needs of that dolphin and others in its colony.
The first clinical signs of recovery from illness in dolphins are usually improvements in overall behavior and appetite—just like us, they have more energy and start eating more normally. On diagnostic tests, we'll look to see bloodwork returning to normal if there were changes. The elimination of inflammatory cells in respiratory, fecal, and stomach samples are also encouraging signs of improvement in the dolphin's health. Just as with people, dolphins may live for many years with some chronic health issues, so sometimes changes don't fully resolve.