If you do choose to use Aspirin for your dog, start small and up the dosage if it doesn’t seem to be working. A standard aspirin is 320 mg, and a baby aspirin is typically 80 mg. That would mean your Chihuahua should only get half a baby aspirin, or 1/8 of an adult aspirin. A Rottweiler, or another 60 pound dog, could get a full aspirin. However, Advil and Aspirin should not be used if your dog has arthritis or osteoarthritis since these have been shown to damage joint cartilage. There are some NSAIDs (Non-Steroidal Anti-Inflammatory Drugs) approved for veterinary use.