Kurtle was a pet who lived with the Zhou family during the Guilderland era, before the move to Peoria, Illinois. The name is almost certainly a pun on "turtle," which suggests Kurtle was one.
The only surviving record of Kurtle is a Chinese homework exercise Amy sent herself on September 12, 2011, when she was ten years old. In it, she describes her family: dad, mom, younger brother (George), herself, and a pet named Kurtle.
Kurtle predates Teddy by nearly three years. Teddy arrived in April 2014, after the family had moved to Peoria. What happened to Kurtle in the transition is unknown.
Teddy got the memorial posts, the family rallying, the written grief. Kurtle got one line of Chinese homework from a ten-year-old, and then silence.