Pathologists: The Disease Detectives

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Zoo InternQuest is a seven-week career exploration program for San Diego County high school juniors and seniors. Students have the unique ability opportunity to meet professionals working for the San Diego Zoo, Safari Park, and Institute for Conservation Research, learn about their jobs, and then blog about their experience online. Follow their adventures here on the Zoo’s website!

Riley_W5_picThis week interns met with Dr. Megan McCarthy, a Resident Pathologist at the San Diego Zoo. Although it may not sound like it, Dr. McCarthy’s job is similar to the work of a detective. When animals die, Dr. McCarthy’s job is to find the cause of death and prevent other animals from dying the same way. The difference is, instead of chasing criminals Dr. McCarthy is hunting down microscopic bacterium and viruses. Pathology, or the study of disease, is a key component of conservation. When disease spreads in animal populations it can wipe out entire species and disturb the ecosystem. Dr. McCarthy and the other Veterinary Pathologists at the Zoo aim to “remove disease as a roadblock to conservation.” From protecting the Zoo collection to identifying viruses in wild animals the pathology department plays a very important role in conservation.

The first step in finding a disease is to take tissue samples from the deceased animal. On our visit to the Hospital, Dr. McCarthy demonstrated a necropsy, or animal autopsy. Necropsies are performed on all animals found dead at the zoo including native wildlife, and collection animals. This way, Pathologists can target the start of disease and inhibit its spread. Once an animal has died, it is important to collect tissue samples from each vital organ as soon as possible. Sometimes, there are obvious “clues” to indicate the cause of death. Other times, the animal looks completely healthy. In both cases, samples are passed on to the histology lab. In histology, the tissue samples are made into microscope slides so the Veterinary Pathologist can take a closer look at what happened to the animal. Identifying diseases is the hardest, but most important part of the job.

Once a disease is identified, preventative measures can be taken to assure the health and safety of the collection. This becomes crucial to conservation efforts. The Zoo holds many irreplaceable critically endangered animals; it could take just one disease to wipe out the entire population. By studying disease in collection animals, important knowledge is gained about diseases in wild populations. The pathology department can help animals that are critically endangered, like the California condor, by identifying the main causes of death and preventing future animals to die in the same way. For example, a wild condor was brought into the Zoo hospital with lead poisoning. Even though it was being treated, it unfortunately died. The necropsy revealed it died from an undiagnosed viral infection. In future cases, veterinarians would know to look for infections and a compromised immune system.

Disease investigation could be the saving grace many species need to overcome extinction. Although there is still little known about diseases in exotic animals, the San Diego Zoo has made leaps and bounds in research. The hard work of Dr. McCarthy and the pathology department have contributed to the health of the Zoo collection as well as the success of the Zoos conservation programs. Dr. McCarthy says her favorite part of the job is to see the animals happy and healthy, and to know that she is making an impact by minimizing the threat of extinction.

Riley, Conservation team
Week Five, Fall 2015