OP, I don't know if you are coming back to comment or read the responses but I have a question for you.
Is your interest in animals or your interest in travel stronger?
Do you have a passion for either?
As many noted here, neither parts are especially glamourous, and the animal part especially involves often a lot of hard work, manual labour, uncomfortable situations, and/or muck. (Often lots of muck)
And then there is the dark side of the animal world - animals in captivity are often kept under cruel conditions. While the circus comment may or may not have been tongue in cheek (it somewhat fits your criteria), I suspect that most animal lovers would be put off by actually working for a circus which still uses animals.