I'm with Amy--I think it is a tendency in the breed.

We had a beagle growing up, named Spike who was a bit on the tubby side. And with Abbey now, I constantly moniter her food intake, and treats, and activity level. If, for some reason she was to quit running around the yard for hours a day like a maniac, I would walk her more. She does tend to put on a little bit of weight in the winter, but usually loses it in the spring--about 5 pounds or less.

My neighbor said to me one day, "Wow, Abbey is getting fat!", and it hurt. I thought it was an incredibly rude thing to say, and I let her know that. Anyway though, they way she is built, you can notice a couple of pounds on her, so I try to limit her treats and food daily. She weighs about 50 pounds right now, but she's tall, like a dalmation or a lab, not small like a beagle normally is, so she's normal for us!!

Maybe you could give Rosie an extra walk..it couldn't hurt