Go back to the last spot you saw them
It may seem like a long shot but go back to where you last saw
your pet and leave an article of clothing (preferably something
that you've worn for at least a day). Go back and check this spot
often.
Post to Social Media
If you have a Facebook, Twitter, Instagram, or other social media
accounts, post information and a current photo of your missing pet
for friends and followers to see. Ask them to spread the word and
help further the search. Also, posting to your local online
community boards like Craigslist, Ring, etc., can help alert
neighbors to keep an eye out or to help with the search.