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Photo of Howard Krum Howard Krum
Doctor Fish

At Boston's New England Aquarium, the medical center is a real hospital where visitors can observe exams and emergency care for animal patients. Veterinarian Howard Krum and his team have operated on some unusual patients, like the bridled burrfish we see on this episode, to build up a repertoire of advanced surgical techniques. Learn more about Howard's work and his patients by reading his answers to viewers questions.

q Did the bridled burrfish (which had the calcification removed from it during this story) recover fully?

A She survived the surgery very well. The incision site healed and she began eating but died a few weeks later. We are still waiting for the pathology results which should help us determine the cause of death. Unfortunately, she was basically a geriatric fish (an old timer) and I don't think she was ultimately strong enough to recover fully. We felt compelled to give her the chance to try and in the process, we learned a new technique that will help some of our other fish patients.

q Of the techniques you have learned on the captive fish, what has had the greatest potential impact on the wild populations of fish?

A This is a very good question. In my opinion, the work we do at the aquarium has impacts on the wild populations of fishes in two main ways:

1) As we care for our patients at the aquarium we discover many new diseases and investigate disease processes (infectious and nutritional) that can significantly affect the animals' health and shorten their lives. When this information is used to enhance the culturing ("Aquaculture") of fish for food or pets we lessen the need to harvest fish from the wild. This is very important since the world's human population grows so rapidly and the demand for fish is so high.

2) If we can enable the display of beautiful, healthy and happy aquatic animals for millions of people to see each year, they may want to learn more and help protect the aquatic world.

q Guthrie was impressive! How long did it take to train him to be so cooperative for his medical tests?

A It took many years for Guthrie to learn these behaviors. He started when he was a youngster (2-3 years old) and he is in his teens now. He has numerous training sessions each week (5-10) which helps to reinforce what he already knows and allows us to change behaviors as needed. For example, he or the other sea lions, may need to be positioned at a slightly different angle for an x-ray or a physical examination.

q Are sea lions and harbor seals related?

A The answer to this question is not known at this time. In fact, there appears to be considerable controversy regarding the ancestry of phocids (seals) and otariids. (sea lions). We do not know if all present day pinnipeds arose from one, two, or more stock ancestors. Many scientists hold the view that the seals without external ears (phocids like the harbor seal) arose from otter-like stock, and the eared pinnipeds (otariids like the California sea lion) descended from bear-like ancestors.

Some references on this topic are as follows:

Scheffer, V.B., Seals, Sea Lions and Walruses, a Review of the Pinnipeds, Stanford University press, Stanford, CA, 1958, 32.

McLaren, I.A., Are Pinnipeds Diphyletic? Syst. Zool., 9. 18, 1960.

Mitchell, E.D., Parallelism and convergence in the evolution of Otariidae and Phocidae, Rapp. P. -v Reun. Cons. Int. Explor. Mer, 169, 12, 1975.

Tedford, R.H., Relationship of pinnipeds to other carnivores (Mammalia), Syst. Zool., 25, 363, 1976.

q My students at Community Catholic Middle School really enjoyed this segment. When it was finished we realized that the problem of the hunch-back sharks was never addressed. Is the cause known? If so can or has it been cured. Thanks for your time.

A Good observation. This health problem is probably a good one to discuss. The condition seen in our "hunch-back" sand tiger sharks occurs at other zoos and aquariums as well and no one is certain of the cause (etiology). In our situation, the sharks appear to be normal when they are younger (3-4 feet in length) and as they grow, their backs slowly deform but not all individuals develop this problem. Affected individuals usually develop that "hunched" appearance which is a dorso-ventral (from back to belly) curvature of their spine. Some of the sharks develop a scoliosis (a side-to-side deviation as well. We have performed various diagnostic tests such as blood chemistry analysis, plain radiography, CAT and MRI scans and had tissues examined by pathologists when an affected shark dies. In fact there is a group of veterinarians and scientists from various institutions consolidating their data and tissue samples to try to learn the exact cause.

Some scientists believe that the condition is nutritionally based, that in fact, the sharks in captivity are being fed excessively (quantity and excessively rich foods). A nutritional etiology is most likely; however, others feel that the deformities could arise from injuries suffered during acquisition from the wild. Sand tiger sharks are usually acquired from fisherman that obtain them as accidental bycatch (not the species being targeted by the fisherman/person). Still others believe that this pathology may occur naturally but is made worse by some aspect of captivity. These people commonly also feel that affected sharks might have perished in the wild but are maintained beyond their natural life spans in the aquarium where "the living is easy", competition is eliminated and food is plentiful. I think that the later theories are unlikely. Hopefully, a definitive answer will be forthcoming.

When a shark develops this condition we are always concerned about the question of patient comfort/pain perception. In some cases we have tried to treat affected sharks with pain reducing medications. But we have no real "feel" as to whether these treatments helped or if the animal was actually "in pain" to begin with. This is a very complicated issue in veterinary medicine even when working with traditional species let alone a shark.

q Dr. Krum, my question is in regards to the unique surgeries that you perform on various sea animals from the Aquarium. I was wondering, since most of these surgeries have never been done before, from where do you draw your information on what exactly to do? What is it that makes you confident that you are doing the right thing? Thank you for your time in answering my question.

A Most of the information we use when working with exotic patients, such as fish, is derived and adapted from work commonly performed on the traditional veterinary species such as dogs, cats, horses, cows, etc. That's why it is so important for people pursuing a career in exotic animal medicine to be well-trained in traditional veterinary medicine practices. Almost every time we are planning a procedure, we consult with our veterinary colleagues at veterinary teaching hospitals, and other zoos and aquariums. It usually takes a long time to become fully prepared and many unforeseen complications can arise. It can be scary.

Doing the "right thing" is an issue that is always on our minds. Many times it is very difficult to definitively decide what is the most effective course of action. If no one has done a procedure/treatment you are planning to perform, there is no track record to evaluate and to give you clues as to the validity of the treatment. That's why we consult with as many people as possible, to hopefully aid us in choosing the best course of action for each patient. Sometimes it comes down to the fact that if you don't try, the animal has no chance at all. As some sort of consolation, you certainly hope that if the procedure is not successful, what you will have learned in the process will help other animals with similar problems in the future.

q When surgery was performed on the burrfish, how did it live without being in water?

A We continuously pumped water over the fish's gills and kept its exposed skin moist.

q What has been the toughest operation you have performed and on what kind of fish was it performed on? And I would also like to know if you have discovered any new medical techniques that you use on fish that could be applied to human surgery?

A Fixing a spinal fracture on a grouper was probably the toughest operation I ever attempted. The animal was a long-term resident of our Giant Ocean Tank (seen with the sharks in this episode). He was normal for years and then suddenly one day could not swim. He was found resting on the bottom of the tank and also would not eat. X-rays showed a serious spinal fracture (broken spine) that was just above his swim bladder. We chose to try to realign the spine and maintain the bone position to promote healing with an external fixator device. As you can imagine, stabilizing broken bones in fish is complicated. The use of the traditional plaster cast is definitely out of the question. An external fixator is basically composed of stainless steel pins that are inserted into the vertebral bodies above and below the fracture site. These pins protrude from the side of the fish's body and are rigidly held in position with a stainless steel rod. This type of apparatus is commonly used to aid in repairing fractures of birds, people and other animals. In this case, all this metal caused the fish to tip to one side so foam floatation had to be wrapped around the metal to provide neutral buoyancy in the water.

The procedure took approximately three hours and the animal recovered and began eating but died several days later. On necropsy examination (an animal autopsy) we found out that a severe fungal infection of the swim bladder had caused the original spinal fracture and the animal's ultimate death.

We have never developed techniques that were applicable to human surgery. However, many techniques we use are adapted from human medicine.

q What are the largest and the smallest animals you have operated on?

A The smallest animals were probably poison arrow frogs which were about the size of your thumbnail. The largest animals I "operated" on (attaching tracking tags/collecting blood for health assessments) have been whales and dolphins.

q I saw the operation you performed on the fish and I was wondering why you spent the time and money to operate on that fish considering that bridled burrfish are not very rare. Also I was wondering if fish operations are taught in veterinary school or if you are just experimenting with a new science.

A A good point. There are several reasons why we perform such extensive procedures even on commonly available animals:

1) We feel compelled to provide a uniform level of veterinary care to all species that we maintain at the aquarium regardless of species status (e.g., common, endangered, threatened). Basically, all animal life is of equal value.

2) Since we brought all of these animals to this facility they deserve the best care that we can provide. We are ethically and morally responsible for their lives. During their stay with us and while they are acting as ambassadors for their species and their home environments we are responsible for their health and welfare.

3) Procedures "practiced" while helping common species can then be adapted to more endangered species when needed.

4) This is a valuable opportunity for teaching veterinary students and the general public visiting the aquarium.

A few veterinary schools do offer limited experiences with such fish procedures. Most of this type of work is learned while the veterinary students are taking individualized courses called "rotations" that are offered on a competitive basis at various zoos and aquariums. A few aquariums such as the New England Aquarium, the National Aquarium in Baltimore and the Mystic Sea Life Aquarium offer one-year-long internship positions for newly graduated veterinarians. This type of opportunity offers the most valuable and diverse training. A new residency training program had begun at the veterinary teaching hospital at North Carolina State University that focuses on aquatic animal medicine. The competition for these limited educational opportunities is intense.

q I have questions about the operation we saw: What kind of anesthetic was used on the fish and how long did it last? What type of material do you use to sew up the fish after you do surgery?

A We use an anesthetic called tricaine methanesulfonate, commonly abbreviated MS-222. It is a white powder that dissolves in water very easily. Its effects wear off completely usually within 10-15 minutes after the fish is transferred to water without the anesthetic agent. We use the same suture material that is utilized in human and other animal surgeries.

q I am watching this show in my class and we have some questions about Guthrie, the sea lion. First, does he get frustrated after a while if he is working to long? Is Guthrie the only trained seal there? If not how did you decide which one to use for a show?

A Yes, he gets frustrated so he will just stop! All the work is on a voluntary basis. We have other trained sea lions, harbor seals and sea otters. The trainers have a rotating schedule for the animals so that nobody gets bored. And many times the choice of performer is made by the animals themselves. Whoever wants to perform the most that day!

q During Doctor Fish, a Zoo trainer told Alan something I thought was particularly fascinating. The person warned of a bacteria that was transmitted by the bite of a seal. I am an eager student of medical bacteriology, and I would love to know the name of this pathogenic seal-mouth normal flora. Please tell me the name of this organism so I might study it further. Thanks for your time and for the ability to ask you in this medium.

A A bacterium called "Mycoplasma phoca cerebrale" has been implicated in the disease. It is usually easily treated with standard antibiotics.


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