The description is of a dog-like pet following my main character

I want it to sound like shes struggling to get up, he's just following at her own pace behind her.

I'm looking for a one or two word phrase that can accurately (and SUBTLY) describe a natural climber.

I'm okay with using the word "natural" (sounds better than "born-" anyway) but don't want to use the word "climber" because it's the title of the chapter and has more relative use elsewhere

This non-overpowering description is to go in a sentence that already has a subject, that is such as but not exactly,

"A girl climbed the ascending stairs of the mountain, followed by a slow-going NATURAL CLIMBER."

Any ideas? Very much appreciated! Thanks