If my dog figured out a way to convince me to feed her more food, she would do it until she made herself sick/died from gluttony. So don't assume he
neededmore food just because he was encouraging you to give him more.
More importantly, is your dog a healthy weight? By that age, you could be able to feel his ribs and hips, but not see the bones standing out.
Standard, according to my google search: The Rat Terrier ranges from about 10 to 25 pounds and stands 13 to 18 inches at the shoulder.
So assuming your rat terrier is a purebred and on the shorter end of that scale, he's about the expected weight, especially since he may not be totally filled out.
Also, congrats on your new addition
