Big Charles, I don't think so! One is in the mint family, and is nepeta catae, and one is in the hemp family, and is cannabis sativa. They also don't nearly resemble each other:
http://www.ces.ncsu.edu/depts/hort/c...b/CannaSa9.jpg
http://www.boldweb.com/greenweb/HR123.gif
Sorry, but I think your vet needs to educate himself! :(