When I was on an externship in Central Maine, the veterinarian I was assisting got a call to come see a reindeer (Rangifer tarandus) that the owner thought was not doing well. The owner stated that she thought the animal had been losing weight, while its herd mates were not losing weight and were thriving. We finished up pregnancy checks at the dairy barn we were at and proceeded to the farm with the reindeer.
When we arrived, we found the animal and corralled it in a run-in shed. When working with cervids (deer species) it is important to be as calm as possible because they are prey species and prefer to be left alone. If you are too rough with them or push them too far, they can injure themselves or the people working with them. Once we were sure the situation was safe, we inspected the animal. It did not have a high temperature, its heart sounded good, and its mucous membranes appeared normal. It was underweight, but it was still eating. It did seem a little depressed compared to its herd mates. It was all up to par on its vaccinations and state paperwork. Chronic wasting disease (CWD) is always a concern with cervids, but this disease was not suspected. It isn’t present in Maine, so state officials are always sure to monitor all cervids that enter the state. CWD is a prion disease, like scrapie in goats and mad cow disease in cattle.
We took blood from the reindeer and took it back to the clinic. We discussed possible causes of the animal’s condition. Parasitic worms were high on the list, as well as Parelaphostrongylus tenuis, the meningeal worm of deer that is common in Maine. I mentioned that Babesia could be a cause. Babesia is a red blood cell parasite that I had seen infect a reindeer in New York State. It was a long shot, but the clinical signs fit. Also, the reindeer was purchased from upstate New York, where Babesia has been documented in multiple reindeer.
We returned to the clinic and I took the blood from the reindeer and made a blood smear. Sure as the sun, once I stained the blood smear and looked under the microscope, the red blood cells were riddled with Babesia parasites. After consulting my parasitology notes to make sure I was not seeing things, I brought my findings to the head veterinarian. All the doctors in the clinic were interested, as many of them had not seen this disease in person before. While it is unfortunate that the animal had this infection, it sure was satisfying to diagnose it!