If the pest controller doesn't make an appearance, you can do something yourself. Looks like the rats are just passing through, so place a bait station in their path. Bait (wheat coated with poison and brightly coloured - no mistaking it) is available from horse/farm/country stores. Proper bait boxes will cost of course, but a length of drain pipe usually does. Long enough to stop the dog getting at it. if the bait comes in single-dose bags just put it in the pipe, else get a small freezer bag and half fill it. You may like to wear disposable gloves. Place the pipe where the rats come under the fence so they have to go through the pipe. While the bait disappears, keep putting more. When it doesn't disppear, you've got 'em!