Invisible Clues

An ashy-headed goose

Working in the Molecular Diagnostic Laboratory is often an adventure. I never know when I am going to get an email or phone call from our Pathology Lab letting me know we have an interesting animal case and they are sending a liver, or a lung, or various other animal parts for testing using our molecular techniques.

When the clinicians and pathologists have a good idea of what disease or pathogen the animal may have, our molecular diagnostic tools can be just the thing they need to confirm and back up their diagnosis. In some unusual instances, our testing may even reveal a pathogen that has never been described in that particular species. One method we use most often is PCR (polymerase chain reaction). With this tool we can use extracted DNA or RNA from the animal sample and amplify it from a few copies to millions of copies. In order to make this technique very sensitive and specific, we use primers that are specifically designed to attach to and amplify certain targeted genes of viruses, or other pathogens.

One interesting case example was a 15-year-old female ashy-headed goose that had died. A thorough review of her health history, as well as a necropsy and histology, was performed. The clinicians and pathologists had an idea as to what organism could be affecting this animal but needed further confirmation so that the lagoon exhibit could be managed in the most appropriate and effective manner. After extracting the DNA from the goose’s cecum and liver, running it on a conventional PCR, cloning (inserting the PCR product into a vector) it, and finally sequencing the PCR products, the clinicians’ and pathologists’ findings in conjunction with the molecular results determined that Avian schistosomiasis, an infestation of trematodes (blood flukes, scientific name Dendritobilharzia pulverulenta) was what made this bird sick.

Having these valuable techniques available is a complement to the management processes that protects and maintains the health of San Diego Zoo Global’s animal collections. Working with such a talented team of clinicians, pathologists, and all the animal care staff is very rewarding and fulfilling!

Jennifer Burchell is a research coordinator for the San Diego Zoo Institute for Conservation Research.

One Response to Invisible Clues

  1. There is a lot of very distinctive waterfowl on Tierra del Fuego. Being isolated at the southern tip of South America, made them develop that way. I wonder if Charles Darwin categorized them, when he sailed through the Straits of Magellan aboard the HMS Beagle on his way to the Galapagos Islands?