The dog walker we have been using for the last 7 years, lost 3 dogs today. Don't blame the walkers, dogs can be unpredictable and it hasn't happened before..
They found the first one within the hour, the other two including ddog took 4 hours to find in a huge remote windfarm woodland/moors area, thought at one point as it was getting darker we would never find them and they would be outdoors overnight. Then Ds(17) found them first and they ran away again!!!!
Eventually managed to get a hold of them both (only because ds is fast), never realised it is so hard to get your dog to come back to you when they've been lost for a few hours!!!!