Personally, I would not because of risk of bleeding in stomach...and it was my former believf that aspirin even to a dog would kill it.
Don't medicate cat on your won is my advice.
CALL and ask the vet 1st but this is what I found on a vet site:
Aspirin may cause birth defects, so it should not be given to pregnant animals.1
Aspirin also interacts with several other drugs, particularly cortisones, digoxin, some antibiotics, Phenobarbital, and Furosemide(Lasix®).2
Aspirin can be given with food, 1-2 times a day. Check with your veterinarian about proper dosing for your dog, and if it is the best drug for your dog. There are safer, potentially more effective drugs out there, such as the glucosamine/chondroitin supplements. Cosequin is a common veterinary supplement that helps with arthritis and some joint problems.
Q: What about my cat and aspirin?
A: Same cautions as above, but with the added warning of time between doses. Cats cannot break down this drug as quickly as dogs (or humans), and thus, the cat can be easily overdosed with the accumulation of the drug in the body. In contrast to dogs and humans, cats are typically given smaller doses at intervals of 48-72 hours. This drug, as with all drugs, should be only used under recommendation and 'monitoring' by your veterinarian.