The ban came as a second infected calf was identified in Texas, and the US state declaring a state of disaster over the outbreak.
Canada's food inspection agency has announced a temporary ban on livestock from the US state of Texas after flesh-eating screwworms were discovered in calves this week.
Cows and horses that were in Texas anytime within 21 days before crossing the border into Canada would not be accepted into the country, an agency news release said.
The announcement comes after the US Department of Agriculture (USDA) said the parasite had been found in a second calf in Texas - the leading US beef and cattle producer. Texas Gov Greg Abbott declared a state of disaster on Friday over the "imminent threat" the outbreak posed.
"This is likely to spread over the course of the summer," Abbott told reporters on Friday.
The New World Screwworm is a parasitic fly whose females lay eggs in open wounds and mucous membranes of living warm-blooded animals and people. When the eggs hatch, hundreds of larvae burrow through living flesh with sharp mouths, eventually killing their host if left untreated.
