Given the sentence provided, write a complex sentence that includes the sentence as a subordinate clause.
The cat ran away.
Although I had taken precautions, the cat ran away when I accidentally left the door open.
Complete the following task based on the instruction and optional input provided.### Instruction:
Given the sentence provided, write a complex sentence that includes the sentence as a subordinate clause.

### Input:
The cat ran away.

### Output:
Although I had taken precautions, the cat ran away when I accidentally left the door open.