Some information from the Providence Journal:

Mercury (a kitten) started Prozac about three months ago, but this isn't his first time on the anti-depressant. About two years ago, Johnson tried a number of drugs to calm her pet, but only Prozac seemed to help the former stray ...in the past ten years, drugs have hit the market giving owners of crazed cats and demented dogs a bit of hope, even if it's not a cheap alternative. Vets said drugs for behavioral problems are much more prevalent than they were five years ago.

On the other hand...

Dr. Drew Weigner, "The Cat Doctor" of Roswell, GA., said more than half of the behavioral problems he sees have a medical basis... A dog suffering from an ear infection may snap when you attempt to pet his head, while a dog with joint pain may growl if you pick her up...

It's very expensive:

Drugs and behavioral therapy often aren't cheap. He [an animal behaviorist] charges $300 to $325 to work with a cat and $500 to $600 for a dog. Anti-anxiety drugs usually run $35-$75 a month, and costs are higher for well-known drugs such as Prozac.

The numbers as it stands:

Still, only about 1 of 1,000 pets recieved medication for behavioral problems, Weigner said. Now he said, that number is probably 50-100 out of 1,000.

This information came from an article by Sandra Eckstein entitled, "Fluffy, Fido a Little Too Feisty".

Success stories abound, and the drugs appear to be safe, causing relatively little side effects. Still, there are concerns over drugs being used without necessary behavior modification, and whether drugs are a natural choice for pets.

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