What kind of animals is Anna asked to look after?

Anna: Hello.
Peter: Hi, Anna. Look, I’m sorry to bother you so late. I just wanted to ask you a little favor.
Anna: Oh, sure. Well, I’d like to help out. Anything you want.
Peter: Look, I’m going to London for a week.
Anna: Oh, how wonderful. I wish I could get away on holiday.
Peter: Look, I have got a problem though, you know, I have got some cats and I need a home for them.
Anna: Oh, er well, the only thing is, how many of them are there?
Peter: Well, there’re only two.
Anna: Oh, well, that’s okay then. I think I still have a box. But it’s pretty worn out and a bit dirty, not too nice, you know.
Peter: Well erm, I think that’ll be all right. I’m sure it’ll be fine as long as you didn’t. I didn’t want to mention this earlier, perhaps, but er well, I didn’t want to mention this earlier, perhaps, but er one of them is pregnant, you see. One of the cats is pregnant and she’s going to be delivering er pretty soon.
Anna: Oh, no I’m a little nervous about it now. I mean er I don’t know if I can cope with that.
Peter: Of course you can. Look, I mean, they’re okay. She looks after her babies. She had six the last time. You’ll love them.
Anna: Six? Wow, that’s just a little too many. I mean, I don’t think I could cope with that, I mean. And how do I tell when they are due, you know, when they’re going to be delivered?
Peter: Very simple. You see, the mother starts spending more time in her box and starts meowing a lot. You will know that she’s ready to have the babies.
Anna: Well, what kind of food do I have to give them?
Peter: Very simple. They don’t need anything and the mother nurses them for about five to six weeks. You just give the mother cat food and milk.
Anna: Well, does it have to be hot?
Peter: No, just fresh milk.
Anna: Anyway, why do you keep them? I mean, don’t they cause you an awful lot of work and trouble?
Peter: Oh, no. They’re so sweet. You’re going to just love them when you see them. They’re so nice.
Anna: Well, here’s an idea. Why don’t you bring what they need, and I’ll just have—then I won’t have to worry about it anything.
Peter: Okay, I could do that. I’ll bring a big bottle of fresh milk and a large box of cat food, then that should be okay.
Anna: A large box? How long did you say you were going to be away?
Peter: Now look, don’t start worrying too much. She may not produce these little cats this week at all.
Anna: Well, I certainly hope not. I mean, I’m not used to this sort of thing, you know.