4743 N. Highway Drive.
2701 S. Sixth Ave.
Arizona Feeds Country Stores were traditionally known for their Arizona Feeds brand horse food. Today, they still sell that. Plus, everything you need for your horse. Plus, everything you need for your other animals. Their website even says that if they don't have what you're looking for, just ask: They might be able to order it special just for you.
2. OK Feed & Supply
3. PAWSH (Humane Society of Southern Arizona)