Arkansas truck driver Michael Siau's nine-month-old pooch Rambo jumped out of his owner's truck when he stopped at a rest area near Hannibal, Missouri and he wasn't missed until Siau had driven on a further 200km.

"Didn't even cross my mind that he might jump out. He never has before," Siau told the Hannibal Courier-Post.

"I jumped back in the truck, put it in gear and drove off. And I just thought he was in the back asleep."

It wasn't until Siau arrived at Cedar Rapids in Iowa that he realised Rambo was missing.

Siau said he began "freaking out" and tried to work out where Rambo had gone missing. But despite his concerns, he made the decision to continue his journey as he knew turning back would mean jeopardizing his job.

Siau's predicament was made worse by a feeling of déjà-vu. In October last year Rambo's father, Ollie, who regularly took trips with Siau, was run over and killed. Siau was so distraught he had to take six months off work.

"I was freaking out. I had to calm down and think about how he could have possibly gotten out," Siau said.

"And it came to me that was the only time he could have got out and I wouldn't have seen him. I was just sure he was there."

Siau said he couldn't bear to lose another dog and began calling local authorities.

After some failed attempts, he got in contact with Hannibal animal control which sent officer Tim Ledbetter to the truck stop. He got there just in time.

When he arrived, sure enough, Rambo was there. He was sitting patiently, but a family who had stopped at the area was just about to adopt the "abandoned" pup.

"In about 60 seconds, he would have been gone," Ledbetter said.

Siau and Rambo were eventually reunited at the Northeast Missouri Humane Society, an animal shelter, on June 5 (pictured above) where Rambo climbed up Siau's shoulder and began kissing the back of his neck.

Together, the pair left for their next stop in Tennessee, with Siau assuring Rambo he would never be left behind again.