Frankenstein's Dog (Goosebumps Most Wanted #4) by R.L. Stine
The infamous, Most Wanted Goosebumps characters are out on the loose and they're coming after you! Catch them all undead or alive!
Kat is reluctant to visit her Uncle Vic Frankenstein because of all the rumors about him. People in the small town where he lives say he's a mad scientist like his great-grandfather, Victor Frankenstein, who created a monster that came alive and terrorized the town. But Kat is relieved to find that even though he lives in a dark, old castle-like mansion, Uncle Vic is a quiet, gentle man, a scientist interested in building robots with artificial intelligence. Also, Kat loves Poochie, Vic's small, adorable, fluffy white dog, funny and playful. But after an accident occurs in her uncle's lab, strange things begin to happen.
Has Kat created a monster? Or is something else responsible for the horror that is unleashed?