Many of you already know how dangerous some human medications can be for your furry friend. But what you may not realize is how other drugs have safely crossed over from people to pets.

For example, did you know that some dogs are being treated with Viagra? But wait — it’s not what you think. Viagra was originally being developed as a cardiovascular medication, but it had completely different effects on male volunteers in the studies. However, it turns out that Viagra is great for treating pulmonary hypertension in dogs.

How about pussycats on Prozac? An antidepressant in people, Prozac helps quell feline anxiety and treat certain behavioral problems.

Particular antibiotics and other medications used in people can also help pets. But a word to the wise: never give your pet a human medication without your veterinarian’s prescription.