Dogs may be given aspirin for injuries or other short-term health issues, according to WedMD. Long-term use of aspirin by dogs is considered risky and can cause increased bleeding, which is due to its blood-thinning properties.
If a dog is going to be given aspirin, it is recommended that they take coated aspirin that is mixed with their food. Over-the-counter aspirin is often prescribed to dogs over other painkillers because it is effective for relieving pain in most cases. Aspirin is an over-the-counter nonsteroidal anti-inflammatory drug that is used primarily by humans, but that is also sometimes given to dogs. When taking aspirin, dogs may experience side effects such as scabs, skin redness, vomiting, diarrhea and behavioral changes. A dog should not be given aspirin anymore if it experiences any of these negative side effects.