Yes, it is difficult on many levels. But the reality is that thousands of wild animals do live in captivity, and even wild places are no longer free of human impact. As veterinarians, we take an oath to help any animal in need. It’s our moral responsibility. It's also a form of direct action for those of us who believe that as humans, we have a responsibility to protect the health of the planet and all of its creatures. We cannot return farmlands to forest or restock oceans—at least not on our own.

In my current job working with mountain gorillas, my patients are free-living, but only to an extent. They're also habituated to people, and their range is limited. Thus routine health-monitoring is possible, though each visit entails hours of trekking up into the mountainous forest.

With unhabituated free-living wild animals, the situation is far more difficult. The vet’s encounter with a patient may often be a one-time event.

So there’s an upside to working on wild animals who live in zoos, aquaria, and wildlife parks. It's much easier to get to know the patient, and the experience teaches us a great deal about the individual animal. There are also the unique challenges and opportunities that come with caring for wild animals in situations where their health depends entirely on humans.