Winter is the season for bovine abortions. Two-thirds of bovine abortion cases are closed with no cause determined. That's an average that holds true in veterinary diagnostic labs across the country. As a side note, miscarriage is not used in vet medicine. Vets use the word abortion to cover the loss of a fetus in animals.
Despite the statistics, I recently had a bovine abortion case for which I was able to get a diagnosis. The fetus looked like all aborted bovine fetuses, that is, not very diagnostic. But this time the vet sent us some placenta, a very rare sample indeed. Bovine placentas are membranes studded with these raised, thick, slightly cup-shaped structures. There are two parts to these structures, a dam side and a fetal side. They supply nutrients and blood and waste removal for the placenta.
At first glance, this sample was fairly typical for placentas (even unicorns have "typical"). It had been picked up off the ground so it had bits of leaves and grass and dirt stuck to it. It was torn so had probably been partially eaten by the dam, foxes, or the farm dogs. But some of those cup-shaped structures looked off to me. Wrong color, wrong texture. I made sure we trimmed those in for histopathology. Turns out they had fungus growing deep inside of them! There was a strong immune response to the fungus, causing disruption of placental function, early fetal death, and the subsequent abortion.
They teach us about all the causes of abortion in vet school. Even so, my histopathologist said it was the first case of fungal placentitis that he'd ever seen in his decades-long career. It will probably be the only one I ever see too. So for once I had a rare successful bovine abortion case.
On the other end of the scale is a bovine fetus I unwrapped a couple of weeks ago. I always do a physical examination of animal remains before starting a necropsy. As I was looking this one over, I noticed that it was missing both ears, the right eye (crows, most likely), the last couple of centimeters of its lower jaw, and then...whoops! I turned it over and found that it was missing all of its abdominal organs. All of them, including the skin of the abdomen and the umbilicus. Neatly removed along with all of the ligaments that hold them in there. The abdominal cavity of that fetus was smooth and clean as a whistle. Farm dogs are efficient. Amazingly, the diaphragm was intact so I sampled what I could--lungs, heart, thymus. Not much hope of getting a diagnosis from this one. I called the vet and asked her why she sent me the case. Turns out she had received a call from the producer about the abortion, and she told him to box the fetus up and get it to the lab. She didn't know it was in such bad shape. I gave her a pass as this does happen now and then.
Production animal necropsies come with unique challenges. In order to get diagnoses for the cause of death, we have to be flexible and creative with the samples that we get.
Except for maggots. I don't do maggots.
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