Animal Autopsies: Gaining Insights From Death to Help the Living

by Michelle Barbieri, DVM

One Friday morning a couple of weeks ago, long before most people finished their morning coffee, the vet lab set to work preparing for some unpleasant handiwork. Our “patient” was a dead stillborn pup, RNX1, retrieved from a nearby beach on Oahu.  The monk seal research and recovery programs needed to know why he died and it was our job to find out.

Data are collected from dead seals by doing an animal autopsy.  We describe the color and texture of each organ and the distribution of any abnormalities.  It is aptly referred to as a gross necropsy (yes, it is stinky and bloody, but it is so called because we are examining the body and organs with the naked eye).

In addition, we collect and preserve tiny bits of organs and send them to a histopathologist who inspects them under a microscope.  If you know anyone who has ever had a biopsy, it was a histopathologist that looked at that biopsy sample to help establish a diagnosis.

Together, gross necropsy and histopathology are the two main ways we investigate causes of mortality in animals.  Using these tools to investigate RNX1’s death is especially important because his other three siblings were also either aborted or found stillborn.

During the necropsy, we found some internal bruising and bleeding around the neck and chest, and noted a few areas of discoloration in the placenta as well, but we could not conclusively determine whether or not these occurred before or after death.  This week, we received the histopathology report on RNX1’s tissues.  It confirmed that RNX1 was a stillborn – his lungs were devoid of air, so we can conclude that he never took a breath.  Additionally, instead of air, the appearance of his lung provided evidence of fetal distress inside the uterus.

RI37

The mother of RNX1, RI37.

Interestingly RNX1’s mom, RI37, sustained trauma to her hind end just before birthing her first stillborn pup in 2010.  The histopathology report from that pup is strikingly similar to RNX1. Could RI37’s injury have involved her reproductive tract?  Scar tissue and an inability to give birth properly could be one explanation for the deaths of her pups.

This is just one example of how our work as scientists can be paired with the keen observations of seals made by our community – in this case, it is helping us determine a cause of death. Fortunately, RNX1’s tissues showed little evidence of infection.  But we know that some viruses and bacteria can cause death without much evidence, both to the naked and microscope-assisted eye.  So we will be anxiously awaiting the results of a few more tests before we make any conclusions.

While many of our efforts are focused on live monk seals, the examination of seals that are found dead is key to understanding threats to their health.  It may not be glamorous, but it is an essential part of what we do – and it turns out to be quite fascinating, if you have the stomach for it…

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