The dogs need about two weeks of rest before another trip to Dawson but how much time do they get?

The dogs needed two weeks of rest, they actually got three full days. On the fourth day, they were off and running.

Three days passed, by which time Buck and his mates found how really tired and weak they were. Then, on the morning of the fourth day, two men from the States came along and bought them, harness and all, for a song.