If don't have your own dog, borrow one from neighbors, relatives, co-workers, etc.
on the streets:
You can find accessories even at the flower and garden shows (like those above shown at the NW Flower and Garden Show).
Try to keep costumes decent. This is an example of bad taste:
The costumes below are more tasteful:
Decorate inside and outside the house:
It's October, but look around your garden. Maybe some fruit are still hanging around:
This picture is not mine. Thanks to the unknown author
Cats are good for Halloween, especially black. Don't have black?
If you were saving on cat food, then try to go for quantity.
The listed components are basic together with treats for kids. You can then add your own special touch.