The incident happened in the Trebanog area of the Rhondda Valley, south Wales on April 7. (stock image)
Police say they have contacted all veterinary practices in the city in a bid to locate the animal.
One couple say the moment their American bulldog was seized was like having a "child ripped away".
DOG PICTURED IS NOT THE XL BULLY IN QUESTION: Emergency services were called to the first floor flat where the dog pounced on the young woman killing her within seconds.
Despite their ferocious reputation, a new study shows that XL Bullies don't actually bite harder than dogs of a similar size.
A court heard that the dog's owner, Justin Allison, didn't do anything to help the girl under attack.