The former Lizzie McGuire star, who is expecting her first child with husband Mike Comrie, has kept fans updated on the pet's condition via her Twitter page.
"Could every1 (sic) please say a prayer for my pup Lola, she has surgery in a half hour! She's a strong girl but needs all good energy sent her way," Duff originally wrote earlier this month.
She later updated after the procedure, posting: "Lola update: she is getting a bit better everyday it was major surgery and I have to keep that in mind. still in the hospital :( home on Tuesday."
However, the chihuahua seems to have taken a turn for the better, with Duff updating fans on Tuesday night (December 20): "Could not have asked for a better gift! Got 2bring Miss Lola home 2day! She is standing up by herself! And taking some steps! Big improvement!"
Duff recently revealed that she prefers wearing tight clothes while pregnant and finds it difficult to shop for maternity clothes.