Spires, Ashley, 1978- P.U.R.S.T. adventure.

"It's all up to Gordon now. His partner has been captured. His superior officer has been neutralized. And his distress calls to P.U.R.S.T. (Pets of the Universe Ready for Space Travel) have gone unanswered. That means he must fight the aliens alone! But Gordon's not a fighter -- his deadliest weapon is his mind. So what's a genius dog to do? Time travel, of course! He'll use his new time machine to travel back in time, then he can stop the invasion before it happens. But there's a malfunction: instead of sending him back five days, the time machine sends him back five years! And now he's out of fuel! With only his wits to depend on, can Gordon get back to the future in time to save his friends and his humans?"--Amazon.com