Alfred F. Jones said:

As far as I know, given my experiences with my own pack happiness being in the gutters, you are forced to use the hot spring. Of course, I could always be completely wrong, and perhaps I'm too impatient after waiting a day or two because I forget that explore exists-

Other players are welcome to correct me though, seriously.

If your happiness is at 0, they will not heal at all. You need to stager your dominance (even if it's only by 1 point). Also, make sure all your wolves have at least a good affinity (excellent is the best). Affinity has a big affect on pack happiness too.

If you have a low of happiness (let's say 10), your wolves will heal, just a very small amount every time the heath script runs (every 15 minutes at #:00, #:15, #:30, #:45). Just try to stagger that dom slightly with your next 30 free CP.