A pet restraint system includes a vehicle floor and a vehicle seat supported by the vehicle floor. The vehicle seat defines a seat-rearward direction. A pet restraint device includes a frame having a lower portion disposed on the vehicle floor and an upper portion supported by the lower portion. The pet restraint device includes a partition supported by the upper portion and is elongated in the seat-rearward direction from the upper portion to the vehicle seat. The partition is telescopic in the seat-rearward direction.