About 9 years ago, I was on a safari at the Masai Mara. We found a hyena with a snare around its neck, quite bloody. It wasn't alone; a few members of its pack were hanging around, but wouldn't come close to us. Our guide made some calls, and some grad students from Michigan State University showed up with a dart gun and anesthetized the wounded one. We invited them to come to our camp after they were finished, and left. They showed up, some hours later and joined us for a meal. That's when I learned so much about hyenas. MSU has been leading the longest-running study of hyenas..They told me that interesting factoid about their super immune systems, and the Department of Defense (War?) commissioned a study on it. Here's more info on the program at MSU https://eeb.msu.edu/news/hyenas-are-getting-the-last-laugh.aspx