On to the review:
I'm not a dog person. Carol Emshwiller's story "The Perfect Infestation" gives me extra reason to be lukewarm to "man's best friend." They might be a ploy for taking over the world.
Usually in science fiction if the world is about to be invaded, it's done with an attack on mankind. They are infested or duplicated or otherwise turned into pawns. In "The Perfect Infestation" the young sees are told "don't bother with the opposable-thumb creatures." They are there to give pats and keep the seeds healthy and well cared for but they are not the main target.
The story follows one seed who has landed in a host unfortunately named Pussy Cat. He belongs to an opposable-thumb creature who still lives with his mother and is looking for love. Pussy Cat ignores another cardinal rule: don't feel loyalty you shouldn't feel. Rather than wait for the signal to launch the second wave of the invasion, he spends his time trying to bring happiness and love to his opposable-thumb creatures.
"The Perfect Infestation" is an amusing take on an invasion tale. It's also a sentimental look at life on Earth. There are moments of reflection with questions such as these: "Does any other world have dragonflies? A single moon? Butter? Pine needles? Strawberries? Chickadees?" (p. 59).