YOU SAID:

I just got a dog to run onto my lap

INTO JAPANESE

私はちょうど私の膝の上に走る犬を飼った

BACK INTO ENGLISH

I just kept a dog running over my knee

INTO JAPANESE

私はちょうど私の膝の上を走っている犬を飼っていた

BACK INTO ENGLISH

I had a dog running just above my knee

INTO JAPANESE

犬が膝のすぐ上を走っていた

BACK INTO ENGLISH

The dog was running just above the knee

INTO JAPANESE

犬は膝のすぐ上を走っていた

BACK INTO ENGLISH

The dog was running just above the knee