Thanks Erica, this goes hand-in-paw with Katy's recent article, "Know Where Your Pet Meds Come From"

I didn't know some of the things mentioned in this article. This is the best takeaway:

"Compounding is necessary sometimes, but be cautious. We believe veterinarians should know that compounding, including formulation in a novel drug delivery system (e.g. transdermal), may impact the absorption and depletion of a drug. This may result in drug concentrations that are above or below the therapeutic range and lead to the development of an adverse drug event, including therapeutic failure."

You just have to trust that your vet is using a good source. If it makes you feel any better, in our almost 7 years online we've never heard of a Tripawd experiencing any issues with compounded meds.