You are right. They call them wickets for dogsIf it's anything like how I measure my horses, you measure at the top of the shoulders, right behind the neck (called the withers) At the barn we have a stick with measurements on it that has a perpendicular bar that slides up and down the stick. We put the stick beside the horse at the shoulder and slide the perpendicular bar down until it is just touching the withers and measure there... I'm assuming it's the same with dogs - but you know what they say about "assumptions"
If anyone has a better description - please share!