Cynthia Yalisove, 63, was arrested on Friday at her Hockessin home off of Horseshoe Hill Drive.
Yalisove's house is directly behind the home of Cindy Aman who owns that dog - named Rip - with her partner and their daughter, who relies on Rip as a therapy dog.
On April 5, Rip went missing from his home on Dogwood Drive. Aman blanketed social media with his picture and locations where he was last seen.
The next day, Good Samaritans from Pennsville, New Jersey notified Aman that they had found Rip, and he was safe and healthy.
Those same people told police that they saw someone in a black Chevy SUV with Delaware plates dump the dog on the side of a road in Pennsville and drive off.
That information led police to Yalisove, and authorities gathered more evidence before an arrest warrant was issued.
Police in Delaware charged Yalisove with felony theft, and New Jersey authorities added animal cruelty charges.
She was arraigned and was subsequently released on her own recognizance.
After the reunion, Aman shared the update that Rip was found on social media, saying "it is horrible what someone did with him, but he is safe and okay."
Action News went to Yalisove's home for comment, but no one answered the door.
There was no word on a motive for the dognapping.
Neighbors told Action News off-camera that the suspect had been building something on her property to keep dogs away from her horses.