Blue Buffalo Pet Products' (BUFF) exposure to PetSmart, which represented 41% of 2017 sales, adds risk that General Mills' (GIS) growth expectations post-deal close may be too optimistic, Piper Jaffray analyst Michael Lavery tells investors in a research note. PetSmart's net debt/EBITDA could bring "supplier headaches" similar to what Toys "R" Us has done, the analyst contends. The analyst lowered his fiscal 2019 earnings per share estimate for General Mills to $3.08 from $3.13 to reflect the risk of more modest expected sales growth. He lowered his price target for the shares to $47 from $49 and keeps a Neutral rating on General Mills.