You do not have to give soft food, you can if you want... the brands that are considered premium in kibble version are usually also good brands in the canned version.
I have heard great things about seabreeze expens, if you are looking for one... that is the best method for containing a new pup.
When I got Chloe I kept them separated except when I could directly supervise them and make sure they were getting along, I never left them together alone because I didnt know how they would get along and Chloe was tiny... slowly their time together increased and now they are together all the time even when I am gone.
Good Luck.
__________________ Armani & Chloe |