Diane couldn't concentrate on General Hospital because Santana her beagle who had been cooped up in the house all day wanted to take a long walk around the lake

Diane couldn't concentrate on General Hospital because Santana, her beagle who had been cooped up in the house all day, wanted to take a long walk around the lake.

Explanation:

Commas in this case go after the word Santana and after the word day.

The objective with this sentence is too pay careful attention to its grammar construction.

The connector because in this case is a subordinating linker which means that it is connecting a subordinate clause to an independent one and the comma is not necessary.