Esta TerBlanche left behind a bunch of animals -- including some very unique pets -- when she died last week, and they had to be collected by a third party ... TMZ has learned.

Law enforcement sources tell us cops got called to the "All My Children" star's home last week when her assistant went to her house to check on her because she hadn't heard from Esta ... who had just returned to the States from a trip overseas.

Our sources say the assistant found Esta Friday on the ground in her bathroom, called 911 and first responders pronounced her dead on the scene.

Now, that scene in Esta's home included quite the menagerie -- we're told investigators found a houseful of pets, including 3 cats, 2 dogs and even some prairie dogs!

Our sources say L.A. County's animal control unit wouldn't take the prairie dogs -- so, as a result, cops contacted a private animal rescue, which sent professionals to collect all of Esta's pets. It's unclear what's happened to the animals since then.

As for Esta ... police found no signs of foul play, and her death is being investigated as natural. They believe the 51-year-old actress actually passed away at least a few days prior to last Friday.

The L.A. Medical Examiner's Office has conducted an autopsy, and her cause of death is pending toxicology results.

Esta was actually a big animal lover, as documented on her Instagram. She had posted lots of photos and videos of the animals investigators found, and from the looks of it, they were beloved pets.