What dog lives with Buck in Judge Miller's house in The Call of the Wild?

Toots, Ysabel, and a few other dogs live with Buck in the house.

Buck is the main dog on Judge Miller’s ranch, at least from his perspective. He is the biggest and the most important dog on the ranch. While there are other dogs, they do not matter to Buck and he doesn’t think they matter as much to Judge Miller.

They came and went, resided in the populous kennels, or lived obscurely in the recesses of the house after the fashion of Toots, the Japanese pug, or Ysabel, the Mexican hairless, strange creatures that rarely put nose out of doors or set foot to ground. (Ch. 1)

There are also twenty hunting dogs, fox terriers, who do little more than yap at the house dogs when they are not going out on the hunt. Buck does not pay much attention to them. They are not much more than noise to him. They are just working dogs. Buck is the favorite.

But Buck was neither house dog nor kennel dog. The whole realm was his. He plunged into the swimming tank or went hunting with the Judge's sons; he escorted Mollie and Alice, the Judge's daughters . . . on wintry nights he lay at the Judge's feet before the roaring library fire . . . (Ch. 1)

Buck’s father, Elmo, was a St. Bernard, which is a very big breed, and his mother was a “a Scotch shepherd dog.” Buck weighed one hundred and forty pounds and carried himself regally when he lived with Judge Miller. No doubt this is why he was valuable enough for Manuel to steal him in the first place.

Buck’s life on Judge Miller’s ranch was an easy one. He did pretty much as he pleased and he was treated as a beloved pet. His life changed forever as soon as Manuel took the leash. Buck assumed he was going for a walk, but he was really being kidnapped and sold into sled-dog slavery.