Chewy is offering new customers $20 off a $49 purchase when you use the code WELCOME at checkout.
Just look for the green banner beneath the product to see if it qualifies for this promotion. (Example Below)
It appears you can stack their Buy One, Get One 50% off promo on treats today with the $20/$49 welcome offer.
You can also get 35% off your first autoship order and 5% after that. It does not appear you can stack the 2 promotions together though.
However this is a great time to stock up on your pet food and save!