[1] - Go to the iams support page and either call them or send them an email, or go here: http://iams.com/contact-us

[2] - Tell them that you bought a 35 lb. bag of (whatever iams dog food you want to put) and when you opened it up you smelled a urine smell and found rat feces as well.

[3] - You will get an email asking you to call in with some information you can do it or you can come up with some reason as to why you cant call in at all. I just said that my phone was away for repair. 

[4] - They will reply if you said you cant call in and tell you they are gonna send you some coupons for a free bag of dog food. I ended up getting a free 35lb bag, and four 8lb bags of iams.

[5] - If you decided to call in then you will need a control group number and expiration date plus a UPC number. None of those things are hard to get. And once you give them that information then they should either offer a replacement or a refund.