What is the expiation for the death of two female dogs due to unintentional neglect?

A Muslim is not permitted to confine an animal and leave it without food or drink until it dies, due to the Prophet's (peace and blessings be upon him) saying: "A woman entered Hell because of a cat which she tied, and did not feed it, nor did she let it eat from the vermin of the earth." If you did not intend that, then there is no sin upon you and no expiation, as Allah Almighty says: "And there is no blame upon you for that in which you err, but [only for] what your hearts intended." It is also not permissible to keep a dog except for hunting or guarding.