How do I let the owner know about the cat rate?

I just got a request to house sit a dog and a cat in October. I have my cat rates setup but the owner doesn't have their cat setup on their profile. I was thinking about letting it slide (it would be my first time watching a dog and a cat) but my mom is HIGHLY allergic the cats so that means before I come back home i'm going to have to wash EVERYTHING just in case and I don't have a problem with that but I feel I should defiantly be compensated for that. I haven't meet with the owner yet. I offered to meet today or tomorrow but they haven't responded back. I know I have some time to meet with them since it won't be until the last week of October. How do I go about letting them know about adding their cat? I do know how to edit the price without having to cancel the booking. Should I let them know about adding the cat rate and just remind them to add their cat on their profile for the next time or next sitter? It would only be an extra $35. I just don't want them to think i'm money hungry but I know i'm going to have to wash everything like i said (plus I like cats lol). Any advice would be great!