You know it’s been a good day when letting your hair down results in the release of the fragrant aroma of ocelot feces. The ocelot in question was artificially inseminated a month ago, and now it’s time to find out if she’s pregnant. Unfortunately, there is no “pee on a stick” method for diagnosing ocelot pregnancies. Abdominal ultrasound would certainly tell us if she is pregnant, but that requires a cooperative animal and weeks of training prior to insemination. Since this was not the case, we were left with measuring the hormonal changes present in her poop.
Diagnosis of feline pregnancy using fecal hormones requires monitoring of progesterone. In cats, progesterone levels increase following ovulation, regardless of whether or not the cat is pregnant. However, the level of progesterone will remain high if she’s pregnant, whereas it will fall again if she’s not pregnant. This fall usually happens a month or so after ovulation. So, to diagnose her pregnancy, you need to first establish a baseline by monitoring progesterone levels for a month before insemination, and then continue measuring it for a month afterwards.
Let’s pause for a moment to reflect on what that last paragraph actually means. Every day or two over a period of two months, zoo staff pick up her feces and place it in a plastic baggie labeled with her name and the date. The feces is stored frozen until the whole lot of it is collected, and then it’s shipped out to a facility which has the equipment to measure fecal hormones (i.e. where I was located for my clinical rotation on Block 18). Once the feces arrives to that facility, it is stored frozen until the staff (or, in this case, the visiting vet student) has time to process it. This involves freeze-drying it, pounding it into a powder, weighing out a specific amount of poop-powder, mixing the poop-powder with ethanol, and then mixing tiny samples of the resulting liquid with reagents for progesterone. The liquid will then change color depending on the amount of progesterone in the liquid. Before this rotation, I wondered why more zoos didn’t analyze fecal hormones themselves. Approximately 1000 breaths of poop-powder later, I no longer wondered.
Ocelot was not the only species of poop with which I worked while visiting the Center for Conservation and Research of Endangered Wildlife (CREW). Other species included black rhino, Pallas cat, and polar bear. While CREW certainly does fecal hormone analysis on their own animals, the samples I worked with while I was there were from other zoos. CREW does a lot more than just fecal hormone analysis. They have multiple “signature projects” focused around conservation breeding programs, and species with which they are working include polar bears, black warrior waterdogs, Indian rhinos, otters, Pallas cats, ocelots, Sand cats, black-footed cats, and fishing cats. Ultimately the goal is always the same: healthy babies that can join the fight to bring their species back from the brink of extinction. However, CREW’s research is tailored based on the challenges faced by that particular species. CREW also has thousands of cryopreserved samples from both endangered plants and animals, carefully stored as a safeguard for the populations which they represent.
I feel extremely fortunate to have had the opportunity to spend two weeks with this incredible facility. As a quick hat tip to the importance of networking, this opportunity became available to me because I attended a talk given by the veterinarian, and stayed after the talk to ask if I could come spend time with her. While there are a few facilities across the United States and the world doing this type of research, there are not many, and I otherwise would not have had the opportunity to spend time exploring this very different facet of veterinary medicine.
And yes, the ocelot was pregnant!
This post is part of a series documenting my clinical year in veterinary school. To read more from the series, please visit the Clinic Series homepage.