Steely, you have AWESOME ideas and a wonderfully creative mind. I have faith in you.
For your dog business, the car sign is a MUST. They are not expensive and can be VERY good ways to get the word out. Every time you have your car in a parking area it will be advertised. Once you have the sign on, start parking in places wehre it can be seen. When you go to the grocery park back near the entrance of the lot where people would pass your car driving in. Make sure that no one can park on that side. It gets business exposure ANd is a way to get a little extra walking into your day (parking at the back of the lot). If you cannot walk far (disabled for some reason, like me) then take advantage of that and use the disabled spots on the ends so that the car can be seen.
Just be CAREFUL that when you put the sign on the car is clean clean clean underneath. Not just been washed clean, gone over with cleaner just that moment to be sure ther eis no grit. Otherwise the sign will rub the grit against the paint, which isn't good. I say this because a friend put a sign up for a business and didn't clean the door before she did it - and her door is ALL scratched up now.
You have signs up at the vet, but have you made friends with anyone who works at the vet offices? You want them to recommend you. So stop in now and then with business cards, etc (check vistaprint for their free stuff - you just pay shipping usually) and bring some kind of treat for the office staff. Cookies are great. If you hear the staff complain about their pens running away, (LOTS of people who work as cashiers complain about this) consider spending some time making pens for them. You can use floral tape to fasten silk or plastic flowers to stick pens, then you put them in a flower pot with some marbles or whatever to keep them standing. It is a lot harder to pocket pens if they have a big fake flower on them. Put your business name/logo on the side of the flower pot. Get the flowers at a thrift store or yard sale.
Make the maps with the business names. You might ask at a pizza delivery place if they have maps or can give you a map - often they have the best maps. Make sure your business name is printed on the map (of course). I don't know if yard sales are a big deal there. they are here. A HUGE deal. Sat mornings the cops jsut ignore a LOT of bad parking if there is a yard sale in sight because they would spend the entire day dealing iwth that otherwise. I used to have a laminated map that I plotted otu where all the sales I wanted to go were so I had a route to follow. I used a map that one of the convenience stores sold and I just laminated it. I had more people buy those out of my hands that I thought was possible. They offered crazy amts of $$ esp as the map cost fifty cents and the lamination was a buck back then.
Lots of people use GPS but many still find it confusing. This might be a good form of advertising for your business, esp given the twists and turns int he area.
You say google has a business complex nearby. Get creative and go do something that can be seen from their offices. An event maybe. Contact pet food companies and see if they need people to give out samples in the area. One of the vets here ALWAYS has samples from some company or other and I know she doesn't pay for them (not only is she so cheap that she would not give away anything ever, she is a neighbor of my folks and has told me she gets them free). Maybe contact an event marketing group if there is an upcoming festival and try to arrange something.
Volunteer in pet related things in your area. I don't know how you feel about organized religion, and that is NOT the point of this suggestion. If organized religion triggers bad things for you, ignore this as it is just an idea. See if a church in the area does a pet/animal blessing. We are a fairly rural area and we have a major agricultural university and a vet school too, so we have a LOT of pet things that happen. I know that the Episcopal and Unitarian churches in town both do a service where people bring pets to church. If a church does this, see if you can give out something with your logo to them and maybe business cards. Homemade dog treats are not that hard to make, recipes are all over the internet, so maybe some of those in baggies with bows? Or just ribbons to decorate collars? Or take food color markers to decorate the animals with "makeup"? I used the Wilton ones and the color mist spray food color. NOT spray icing, it is just food color in a spray bottle. IT can be used iwth stencils. I have gotten vet approval to use these - this was important to me because I used them on cats and cats lick their fur. But kids would go NUTS for a pet version of face painting in the park at an event or outside after a church service where they brought pets to bless.
I am assuming you have a logo. Do you have a shirt iwth the logo? While ordering a bunch of them with the logo might be too expensive, Vistaprint will do shirts. A couple years ago I used their caricatures to design one iwth all the kids and grandkids for my dad. They had a deal for a "free" shirt where you designed it and paid shipping. Shipping was under $10 so it was a good deal for my purpose. If you don't want to do that, get creative and put it on a shirt for yourself. At events, wear the shirt as you give out business cards.
I can think of other ideas if you give me some examples of the logo, the target market, where and how you have started to spread the word. I will be happy to help in any way I can - my degree is in marketing and I have done a lot of event marketing, etc....