I apologize for the lengthy background, but I'm not sure what is important and what is trivial, so thought it would be better to err on the side of too much information rather than too little.

I belong to a group that is putting on a fundraiser for the group. I am a member of one of the subgroups responsible for one aspect of the fundraiser. We have been having meetings at various coffee shops, but because of scheduling issues, I offered my home as a place for the last meeting.
I only know one other member of the group fairly well...the other women are more acquaintances that I have worked with fairly casually in other situations. None of them but the member I know has been to my home before.
We have two cats, so I checked to make sure that no one had any issues with allergies/fears and was assured that that was not a problem. So, everyone comes to my house and the two cats come out to meet them.
People were patting the cats (who are both attention hogs) and then, just as we were about to get started on the meeting, one of the women I don't know very well said in a very accusatory tone: "Why have you been so cruel shaving the white cat? Don't you know how incredibly awful it is for them to be shaved?"
While I wasn't thrilled with her tone, I did politely tell her that that particular cat had had surgery to remove her entire large intestine and due to the surgery, was unable to deal with hairballs. The vet had told us to keep her shaved to eliminate the problem and she had three heated beds as well as our heated waterbed to choose from if she got cold.
And then the woman launched into a lecture about how wrong I was, how my vet knew nothing and I could see everyone in the group getting more and more uncomfortable.
The only way I could see to stop the conversation was to tell her that I was just going to have to agree to disagree with her and that we needed to get started on the meeting. She interrupted me (and this is where I fear I was rude) to start in again and I said: "My vet and I have this under control and I do not wish to discuss it further, please stop."
She did stop (thank goodness!) but the rest of the meeting was fairly uncomfortable with people just hurrying to get it finished and leave.
What could I have done and said differently other than keeping the cats shut up in a separate room so that no one could see that one of them has a clipped coat? It really bothered me that the other committee members were made so uncomfortable by the exchange, but I couldn't think quickly enough to figure out a more effective way to shut down the conversation!