Arithmetic overflow error converting expression to data type datetime???

When I issue this statement i get the following error

ALTER TABLE "Archived Greyhounds"
ALTER COLUMN "Whelp Date" DATETIME
GO

Server: Msg 8115, Level 16, State 2, Line 1
Arithmetic overflow error converting expression to data type datetime.
The statement has been terminated.

I know what is causing the problem.  When I look int he table the dates come back in MM/DD/YYYY, so when sql server tries to do a convert it is interpreting the DD as a MM and crapos out, no such monch as 13 and all that.  I just have no idea how to fix it?  How can I tell sql server what format the dates are in so it will convert the column correctly?Start Free Trial