The key thing to remember about zts is that it is a GROWTH stock and it is constantly compared to a mature value stock (PFE). The reason for the metrics being reasonable high is due to the fact that you are investing in a stock that has a unique position in a new market, with a growing bottom line. Look at zts's EBT margins since 2009. They have gone from -5.36 in 2009 to +16.37 in 2012. This trend is still moving in the right direction, thats what intrigues major institutions and I believe by 2014 we will not see this stock in the 30's again.
Wthh a p/e of 33, a p/b of 22 and a p/s of 3.6, this is no value stock. Moreover, it is not a growth stock either. ZTS was once a part of American Cyanamid, which i used to follow many years ago as an analyst. A large part of its product line still consists of mature antibiotics which are mixed with animal feed to prevent disease. Hang on to your PFE imo.