Something tells me a goose wouldn't be much of a deterrent for these dogs.
Something crossed my mind about the Kangal.
The Kangal has been bred to protect livestock. Domestic geese are livestock as they lay eggs for people to eat.
It would be uncharacteristic for a livestock guardian to kill livestock. Even something as ill-tempered, mean, and deserving of death as a goose.
I predict that a Kangal would tolerate a goose attack, and simply walk away.