The Government of Canada is not party to The Hague Apostille Convention.
Canadian documents for use in Uruguay and Uruguayan documents for use in Canada must be authenticated and legalized by the appropriate Canadian and Uruguayan authorities before they will be accepted.
Uruguayan Documents
Uruguayan documents for use in Canada must first be legalized by the Ministry of Foreign Affairs of Uruguay and then authenticated by the Consular Section of the Canadian Embassy in Montevideo. A consular fee applies.
Uruguayan documents that have been legalized by the Ministry of Foreign Affairs in Montevideo may be sent to the Consular Section by traceable mail along with a covering letter and proof of payment of the consular fees, or brought in person to the Embassy during business hours.
Canadian Documents
Canadian documents must be authenticated by the 
Department of Foreign Affairs and International Trade in Ottawa, and then legalized by the Embassy of Uruguay in Ottawa, before they will be accepted by Uruguayan authorities.
If you mail your document(s) for authentication in Ottawa, you should include a letter requesting that the Department forward your document(s) to the Uruguayan Embassy in Ottawa for legalization. You should also enclose a second letter for the Uruguayan Embassy with your return address in Canada.