1. You'll be able to find the people that you are looking for.
2. You will have a paid listing for your business that could get you more good exposure and it may help get your rankings up in the search engines.
So here are a couple thoughts I have about this as I have had to deal with issues of this nature in the past with a couple of former clients.
If you are worried about getting rid of a bad review that someone has written on the bathroom wall, you're wasting your time. It's not coming off no matter what the cost. Once something has been indexed the only way to get it out of sight is to write article after article that promotes your business using the same keywords they are using to harass your business.
Let's face it, the internet is the easiest place to throw up anything you want in regards to a business. We actually had to hire writers to help create a ton of articles to stay ahead of the people that were trying to bang up my clients. It was nerve racking, but we got it done over a period of about six months. It may be much easier to just ignore it, and allow people to come see for themselves how it is humane and how you help animals legally find peace when necessary.
Another thing you can do is launch a PR campaign that will allow your story to get out on the news and into your community. Make sure you get a copy of it and post it to YouTube.
One more thing, I understand your concern, but sometimes this type of publicity makes more for opportunity than hardship. Look at this is for what it is. A mere smear campaign that won't really affect the smart, especially when you educate them with the truth.