Medical, dental, and veterinary supplies cataloger Henry Schein announced yesterday that it had agreed to buy Los Angeles-based Colonial Surgical. Terms of the cash deal were not disclosed. The acquisition of Colonial, which had more than $40 million in sales last year, will strengthen Melville, NY-based Schein’s position in the examination-gloves market. Schein expects the deal to contribute $0.02-$0.03 a share to its earnings for the second half of 2003.