My friend (hi Dave) randomly (as far as I know) asked me the other day if I had read "Roog" and I said I hadn't even heard of it. I then googled it and confessed I had not read anything by Philip K. Dick, period, although I really enjoyed Blade Runner and other things inspired by his work.
Dave told me it was Dick's first published work and sent me a link, and upon seeing it was all of four pages, I dove right in. (But not before saying "roogh!", my mind making an association with this amusing poem.)
I told Dave I thought the story was a "weird little bugger," a take which I will elaborate on here! I think the story distills and effectively captures a couple of important and universal themes, which per Dave are central to Dick's work.
First, it conveys the inner perspective of a character—in this case a dog, Boris, who feels a strong duty to protect his owners from the "Roogs" he perceives as regularly stealing food his owners have carefully secured and left out (for safekeeping I guess). In actuality (or not? more on this later!) the Roogs are simply garbagemen making their rounds and collections. But based on Dick's description of how Boris perceives the Roogs, they have an alien, menacing quality, and one even at one point samples a bite of an eggshell he picks out of a trash bag.
We also learn that Boris's owners are becoming increasingly exasperated at his barking ("roog!") efforts to warn and protect them, oblivious to the desperation and duty that are motivating him.
Second, there is the question of whose perception is accurate. There is an obvious reading where this is the story of how a dog can see things in an alien manner, blinded by his loyalty and sense of duty, detecting danger and otherness when it isn't really there.
On the other hand, we are presented with no information suggesting that Boris is anything but a loyal canine—and we know dogs have heightened senses in important respects—so perhaps we ought to put some trust in his sense of what the Roogs are like and what they are up to!