The former "Teen Mom 3" star tells TMZ ... her neighbor in Miami, OK unnecessarily reported her for leaving Hank, her Harlequin Great Dane, alone in the backyard while she went on a cruise in the Bahamas.

Mackenzie says it's total BS that anyone thought she abandoned Hank. She says her mom and other family members were tending to the dog every day and Hank's pen was cleaned out daily.

As for pictures that surfaced showing dog feces throughout the pen ... Mackenzie claims the picture was taken right after Hank pooped. On Monday, the neighbor called animal control, which removed the dog -- but Mackenzie says that was because there had been tornado warnings in the area.

We've called animal control to confirm Mackenzie's side of the story ... but we're waiting to hear back.

Witnesses, however, paint a very different picture. We're told the neighbors called animal control because there was a storm Sunday and felt bad for Hank. They claim he had been crying for 4 days and whimpering outside without any decent cover from rain. We're told the neighbors added a wood pallet so Hank would avoid sitting in mud.

This, of course, is the latest incident involving animal control and a 'Teen Mom.' As you know by now ... Jenelle Evans' husband, David Eason, is under investigation for animal cruelty for fatally shooting her French bulldog. The fallout since has been immense ... Jenelle's kids have since been taken away from her but she continues to stand by him.