entered a definitive agreement to be acquired by

Laboratory Corp. of America

(LH) - Get Report

for $23 a share, or about $480 million plus $250 million of assumed debt.

Dynacare is a Toronto-based clinical laboratory company. The acquisition, which has been approved by its two largest shareholders, will be carried out with $11.50 in cash and 0.1164 shares of LabCorp common stock.

Dynacare also ended joint ventures in Pittsburgh and Schenectady, N.Y, and will take an after tax charge of about $4.7 million to reflect the actions.

Dynacare's stock was up 21% to $22 in the premarket Instinet session.