A genetic relative of this rat, seen on the streets of Swift Current, Sask., last week, was disposed of in Calgary on Tuesday. (CBC)

Alberta is once more "rat-free" after provincial inspectors captured a single varmint believed to have entered the province from neighbouring Saskatchewan on a recreational vehicle.

There are no signs the rat infestation has spread beyond the single rat that was caught and disposed of in Calgary's Coventry Hills neighbourhood, Alberta's Rat Patrol inspector Phil Merrill said Tuesday. The rodent was discovered there last week.

"We are confident that we only have a single rat infestation that they've caught and trapped," Merrill said. "We found the rat had moved underneath a little building and it kind of set up a home there [but] they saw him and trapped him and got rid of him."

Merrill confirmed only one rat was found at the site, adding it probably came into the province by hitching a ride on a recreational vehicle from Saskatchewan.

What officials thought was a second juvenile rat turned out to be a large mouse, but animal services will continue monitoring traps and bait in the area.

Two dead pet rats were also found in Fort Saskatchewan, near Edmonton, on Monday afternoon.

"One of our staff from Edmonton went out and looked at the suspect rats and determined that the rats were pet rats … not the wild Norway rat," said Rob Pulyk, an inspector with Alberta Agriculture.

The rats were likely released by someone who heard that pet rats are illegal in Alberta, Pulyk said.

Alberta has taken pride in its "rat-free" status, which means there are no established settlements of rats in the province.

Rat control costs the provincial government about $500,000 a year but the effort is said to save tens of millions of dollars in potential crop damage, disease, food contamination and damaged buildings.

On Tuesday, Premier Ed Stelmach praised the efforts of city and provincial pest control services, saying their long-term commitment is helping to keep Alberta free of rats.