Ever had your dog or cat leave you an unwanted "present," the kind you really wish they'd left outside? Right now, I'm betting that's how PetSmart (NASDAQ:PETM) investors feel.

Granted, shares of the pets-are-people-too retailer are rebounding today, after yesterday's 4% sell-off, but they're still down a considerable chunk of change from last week. The cause of all the commotion? CEO Philip Francis can tell us about that: "We're clearly operating in an uncertain economic environment, and we believe recent consumer weakness may be impacting our business."

Although PetSmart's boss insists he feels "quite positive" about the company's prospects for the long term, Q3 is shaping up to be a rough one. PetSmart's same-store sales growth is expected to be "below its original low-to-mid single-digit forecast." Granted, if PetSmart is still calling it "growth," a Fool can probably infer that same-store sales will at least be minimally positive.

Interestingly, the September reports Target (NYSE:TGT) and Wal-Mart (NYSE:WMT) both just issued, reflecting 1%-ish same-store sales gains, tells us that these megaretailers' diverse product offerings aren't giving them a whole lot of protection from the same spending trends hurting PetSmart. (However, the much larger comps gains at Costco (NASDAQ:COST) and BJ's (NYSE:BJ) suggest that perhaps they should.)

Getting back to PetSmart, third-quarter profits are expected to come in between $0.17 and $0.20 per share. Full-year estimates also got a newspaper-whack across the nose at PetSmart; for all of 2007, we're told to expect $2.02 to $2.07 per share in earnings. Roughly 23% of that will come from a one-time benefit from the firm's sale of shares of MMI Holdings.

This is actually good news, however -- at least relatively speaking. While the earnings warning tells us to expect 16% fewer per-share profit pennies for Q3, it's little more than a nail clipping on the full-year results. Because PetSmart previously expected to earn about $2.09 per share for the year, a pullback to $2.05 is a mere 2.9% decline -- and it's probably not coincidental that after today's bounceback, the shares remain down around 3% from before the news broke.

So "consumer weakness" affects PetSmart after all? Funny. That's not what Phil Francis was telling us last year. Read our interview with PetSmart's CEO and compare notes. 

Wal-Mart is an Inside Value pick, and PetSmart and Costco are Stock Advisor recommendations. Need new ideas for your money? Talk stocks with other investors and our analysts when you try our newsletters for free for 30 days.

Fool contributor Rich Smith does not own shares of any company named above. The Motley Fool's disclosure policy is fully housebroken.