I'm halfway through my necropsy rotation. I've not blogged about it yet not because I'm terribly busy (I'm not) but mostly because it's just depressing.
A necropsy is an autopsy or "post-mortem examination" on a deceased animal. Why they call it a necropsy, I have no idea.
And what we do during a necropsy is basically what they do during human autopsies: namely, cut out and examine all of the organs.
Over the last 5 days, I've necropsied dogs (young and old), cats (kittens and adults), cattle (beef and dairy, bulls/cows/aborted fetuses), horses (adults), and a koi (16 years old).
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Warning: the following information is not for the faint of heart. You've been duly advised.
Here's a sample of how we do a necropsy.
1. External examination of the animal, noting any bruising, swelling, masses, etc.
2. Lay the animal on its back (or on its side, in the case of large animals). Use a giant knife to make an incision through the skin on the underside of the animal, extending from the point of the chin down across the chest, across the abdomen, and down to the anus. Use the knife to cut the skin away from the subcutaneous tissues along either side. Cut through the muscles that bind the scapula to the thorax, so the forelimbs can be splayed flat out to the sides. Cut through the hip joints so the hindlimbs can be splayed out as well.
3. Poke a hole into the abdominal cavity. Cut the musculature along either side of the abdomen to expose the cavity. Look for any free abdominal fluid.
4. Pull back the liver so you can see the diaphragm and look for any holes. Poke a hole in the diaphragm and make sure air rushes into the chest cavity.
5. Use a knife to cut through the muscles along the ribs on either side of the chest. Then use giant garden shears to cut through each of the ribs so you can eventually pull off the underside of the rib cage to expose the thoracic cavity.
6. Use a scalpel to cut along the inside of the mandibles on either side under the jaw, so you can cut out the tongue. Disarticulate the hyoid apparatus (the tiny bones that suspend the tongue muscle). Peel the tongue back, down the neck, cutting connective tissue to free the trachea and esophagus as you go. Cut the esophagus, vena cava, and aorta where they enter the diaphragm. Remove the "pluck" in its entirety (includes the tongue, tonsils, thyroid, trachea, esophagus, thymus, heart, and lungs).
7. Flop the liver up into the now-empty thoracic cavity to get it out of your way. Cut out the omentum with the spleen attached.
8. Push the feces out of the rectum. Cut through the rectum, then cut through the connective tissue that suspends the intestines within the abdominal cavity until the intestines can be entirely removed, along with the pancreas and stomach.
9. Cut out the liver, gallbladder, and diaphragm as one unit.
10. Cut out the adrenal glands.
11. Cut out the kidneys (with ureters attached).
12. Cut into and examine the lining of the urinary bladder.
13. Examine each organ (tongue, tonsils, thyroid, trachea, esophagus, heart, lungs, lower airways, pulmonary vessels, thymus, spleen, omentum, mesentery, rectum, cecum, ileum, jejunum, duodenum, pancreas, liver, gallbaldder, diaphragm, adrenals, kidneys, urinary bladder) in detail. Take samples of most of those organs to submit for histopathology.
14. Cut out a femur or humerus and have it sliced in half so you can look at the marrow.
15. Cut open some or all of the joints (hocks, stifles, hips, elbows, carpi) to look for arthritis.
16. Cut off the head. Hack open the skull with a meat cleaver so you can remove and examine the brain.
17. Clean up.
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See why I'm not having very good dreams this week? The 'highlight' of Friday morning was cutting off a 3 week old kitten's head. The 'highlight' of Thursday morning was watching a live cow being shot then exsanguinated in the parking lot so we could necropsy it. Who knew, but it turns out that not all animals that arrive at necropsy are dead yet. Well, we fixed that.
It's heartbreaking when you let yourself realize that all of the animals (at least the small animals) were someone's pet with a name and a history and relationships. It's easy (and often helpful) to forget about that and just hack out the organs in a routine fashion, but sometimes it strikes you that this dog was only 2 years old, or look how cute this kitten was, or you think about how much pain one of the animals must have been in before it died, based on what you find on necropsy.
So, yeah, I'm ready to be done. If I'm to look on the positive side, at least I've gotten a good review of basic gross anatomy. And I'll undoubtedly need to do at least a few necropsies during my career. And I've learned an efficient way to decapitate a pet for the times when I need to submit a specimen to the public health department for rabies testing.
But that's about as positive as I can be after 5 days of eviscerating, dismembering, and decapitating dead animals, with another 5-7 days (depending on how many cases arrive next weekend) to go.
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