We got Angus because we thought Rosie needed a puppy. Rosie is our six-year-old Lab mix, a barky, gentle girl just under 50 pounds, with giraffe legs and quirky ears. She had always lived with another dog, so when our old dog, Riley, died in November at age 16, we worried that she would be lonely.

Enter Angus in late December, just seven weeks old.

The first time Angus and Rosie met, it was love at first sight. Rosie did the most beautiful play bow and they ran all over the house, played in the yard, rolled each other, growled playfully. It was joy personified. (Or canine-ified.)

And then the nice people from Heart of a Border Collie who had brought us Angus said goodbye and left, and Angus stayed.

It took a little while for Rosie to figure out that hey, wait a minute, isn’t it time for this little dog to go home?

But this little dog was home.

So, briefly, love turned to something else. Jealousy, maybe. Wariness. Possessiveness. Or maybe just putting him in his place, establishing the order of the pack.

Rosie has never been inclined to share her toys, her treats or our attention, but fortunately Riley never cared. Now here was an adorable ball of fur who, like Rosie, thought everything in the world was his.

The first sign of trouble came with a fleece toy. Toys, we have found, have a hierarchy: good, better and high value. Tennis balls and rope pulls seemed to be good or even better toys, but the fleece puffy that we bought for Angus turned out to be extremely high value.

We gave it to him — and nearly sealed his doom. Rosie roared over to him, barked ferociously, showed all of her teeth, Angus shrieked, dropped the toy and darted under the dining room table. We immediately, grimly, picked up every single toy, put them in the Woof! toy box, put the toy box out of dog reach, and put the dogs in their crates.

It was weeks before we dared take out the fleece toy again. By then, it had dropped to good value and there were no more problems. (It helped, too, to buy a second one.)

The second sign of trouble came at feeding time. Somehow, I thought I had been told that the puppy should be fed first, so as it to keep it occupied and away from the older dog’s food bowl.

This was exactly wrong.

So every evening I’d pour the kibble into bowls, tell Rosie to sit and wait, and carry Angus’ bowl out to the front hallway, where he was hopping around doing the joyous Snoopy dance in anticipation of food.

Rosie seemed agitated by this, and she refused to sit and wait, but instead followed me anxiously. This puzzled me, because I did not understand the Rules of Dogdom.

Finally she made her objections clear. I was preparing their food one evening when she suddenly went after Angus, ferocious sounding, bark, snarl. She did not hurt him — I am sure she would never hurt him — but boy did she put him in his place, and boy did she scare me.

And, as it turns out, she was right to do this. I had the rules backward: Puppy does not eat first. Alpha dog eats first. That would be Rosie. Once I figured that out, all has been calm.

So now Angus waits in his crate while I put Rosie’s food down, and then I feed him. After a day or two of screeching, he now waits quietly, knowing what is coming. (I won’t give him his food if he’s clamoring.)

They are back to playing stupendously, snuggling together for naps, and being the best of friends.

Until, of course, my next screw-up. Stay tuned. There’s sure to be one soon.

Laurie Hertzel is the Star Tribune’s senior editor for books. She is not a dog expert, just a dog lover, chronicling the first months of her puppy’s development.

 Coming April 7: Time for leash training. Read previous installments of the Puppy Chronicles at startribune.com/puppy