Breath of Fury attached to another creature you control that does not have summoning sickness.
An opponent cannot block creatures you control.
Steps
Declare the creature with Breath of Fury attached as an attacker.
Dogmeat's second ability triggers, creating a 2/2 Cat creature token with haste due to Jinnie Fay.
Deal combat damage using the creature that has Breath of Fury attached.
Breath of Fury triggers, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to the Cat token, then causing you to untap all creatures you control and to get an additional combat phase after this one.