Dogs can be given small doses of aspirin under certain conditions and with supervision from a licensed veterinarian. Dogs do not metabolize aspirin the same way humans do and are more prone to adverse effects from the drug.
Although aspirin is not specifically FDA-approved for veterinary use, it is a common over-the-counter medication used for treating pain in dogs due to its availability and low cost. The kind of aspirin given to dogs is usually buffered, meaning that it is coated with an antacid to prevent an upset stomach. Aspirin should also always be given with food to prevent stomach issues. Dogs that are pregnant, nursing or are scheduled for surgery should abstain from aspirin, and the drug should never be given to dogs with asthma or kidney disease. Aspirin products that combine the drug with caffeine, codeine or acetaminophen are potentially fatal to dogs and should be strictly avoided.