If you find zoo unethical, you may want to visit a sanctuary instead. All the animals at Wildlife Learning Center were rescued from previous owners who abandoned them or zoos that could no longer afford to take care of excessive animals.
Located a little north of downtown LA in Sylmar, WLC offers a variety of programs that let you interact with some of their rare animals such as a sloth, wildcat, porcupine, burmese python, porcupine, and prairie dog!
My friend and I wandered around the place, which was pretty small, and we were done in a little less than an hour. We decided that we wanted to stay longer since it was such a far drive from Orange County for us, so we paid a little extra to pay a friendly sloth a visit.
We entered the cage with a knowledgeable guide who did a great job at educating us about the sloth and about the place as a whole. We got to pet the sloth. Although I tried not to touch him too hard as I doubt he liked being touched by a random creature.
The sloth definitely made it all worth it for me. If you come with a big group like a birthday party for your son or something, they have a great program where you can pay about $150 for 10 people and you get a private tour for your group and interact with four different animals.
One Cool Thing Every Weekend 
Thanks for sharing this!
One suggestion: Sylmar isn’t really close to downtown LA, but you write that it’s “a little north.” This might make people think that you’re referring to, say, Atwater Village or Highland Park. Perhaps edit to indicate that Sylmar is about 30 minutes’ drive from downtown?