You can use baking soda and water to bathe dogs. I have three dogs, and I bathe them at home. However, my vet, Animal Place in Miraflores, is fantastic, and they do grooming. I highly recommend them. We also purchase our food from them as well, because the food in the markets is of very poor quality.
It's hard seeing all the dogs roaming the streets, and actually, that's how we ended up with our third dog, Camote.