Law enforcement sources tell us Santa Monica PD decided to let the case go ... because the 25 dogs they found in Bryniarski's RV all checked out "healthy and happy."

TMZ broke the story ... Bryniarski -- aka psycho linebacker Latimer from the '93 movie -- was arrested last week for animal cruelty when police found the pomeranian pups unattended in the RV.

Andrew always insisted he was merely running a mobile adoption center for the dogs ... and said they were in good health and well fed.

Now, he plans to reunite with the dogs as soon as the shelter opens this morning -- and tells us he will continue operating the adoption agency from his RV ... just not in Santa Monica.