I'm not sure if this is the correct place to post this thread, so forgive me if I made a mistake.
Anyway, I decided to volunteer at a local animal shelter. I emailed the couple in charge of the shelter, and was very excited when they emailed me back allowing me to volunteer. But I have a few questions that keep on rolling around in my mind. Any answers would be much appreciated

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What should I be expecting from the dogs that I'll be asked to look after for? (which would include cleaning out their kennel, walking them, playing with them, and perhaps grooming). Could their be aggressive behaviour? And if there is, what would be the best way for me to handle this? And also, I'm worried about timid behaviour? What is the best way to have a dog trust me? You see, while I do have dogs on my own, I have never experienced either aggressiveness or timidness in either of them. So having a dog that has these problems would be a challenge for me.
And if anyone has volunteered in a shelter before, or knows someone that has, can they tell me what to expect exactly? For instance, did you/they enjoy volunteering? Would recommend it to a friend?
Oh, and I should mention, this shelter has both dogs and cats. And in the email the shelter sent me they indicated I would probably end up working with dogs. But would it be wise for me to learn about how to care for cats? As I know nothing at all about cats.