Dental and veterinary supply maker Patterson Companies Inc. said Thursday its fiscal first-quarter net income fell about 10 percent, as the company saw modest growth in part of its biggest business and took a charge for its employee stock ownership plan.

The company also announced that a subsidiary has bought American Veterinary Supply Corp., which it said serves practices in the New York metropolitan area and has sales of about $25 million. Terms of the deal were not disclosed.

Patterson, which is based in St. Paul, Minn., and distributes dental, veterinary and rehabilitation supplies, earned $48.6 million, or 42 cents per share, in the quarter that ended July 30. That compares to $53.9 million, or 45 cents per share, in the same quarter last year.

Patterson said it earned 45 cents per share, excluding employee stock plan costs.

Analysts on average expected adjusted earnings of 44 cents per share and $866 million in revenue, according to FactSet.

Revenue grew about 6 percent to $847.4 million, excluding the impact from an extra week in last year's first quarter. Counting revenue from that extra week, revenue slipped less than 1 percent.

Patterson's shares fell 11.2 percent, or $3.34, to $26.57 by mid-afternoon, while broader trading indexes were only down around 1 percent.

Sales for the company's largest business, Patterson Dental, climbed 4 percent to $533.4 million. The company said sales of consumable supplies in that segment grew modestly, due in part to the impact of a sluggish economy. New technology equipment drove the growth.

Patterson Medical sales grew 12 percent to $134.4 million, mostly due to the June 2010 purchase of some DCC Healthcare businesses and favorable foreign currency adjustments.