When I was a child, my family lost our little puppy
Pooka to a large owl.

Watch out for birds! Always go outside with your pup during the Spring/early Summer (mating season), and make a little noise. You never know what could be lurking.
And for God's sake, fellow Floridians, please don't walk your dog around lakes this time of year!
Luck to you all,
Theo's mom