Indentify Skeet and Nig

From the text:

For that matter, they were all loafing,—Buck, John Thornton, and Skeet and Nig,—waiting for the raft to come that was to carry them down to Dawson. Skeet was a little Irish setter who early made friends with Buck, who, in a dying condition, was unable to resent her first advances. She had the doctor trait which some dogs possess; and as a mother cat washes her kittens, so she washed and cleansed Buck's wounds. Regularly, each morning after he had finished his breakfast, she performed her self-appointed task, till he came to look for her ministrations as much as he did for Thornton's. Nig, equally friendly, though less demonstrative, was a huge black dog, half bloodhound and half deerhound, with eyes that laughed and a boundless good nature.