From the CBSA/ASFC Prohibited Goods list:
You cannot import used or second-hand mattresses into Canada unless you have a certificate that verifies the mattresses have been cleaned and fumigated in the country of export. A letter, or any other document that clearly demonstrates that this requirement has been met, is acceptable if it is signed by a person qualified in cleaning and fumigating.
If I go hiking in Canada, I would like to bring my camping mattress. Does the restriction on importing mattresses apply to strictly outdoor camping mattresses?