That being said, I did lose a Chesapeake Bay Retriever back in the 70's when some dude thought he was a duck. RIP Rebel.
This is true about "spray" shot, they are not round anymore and therefore are not areodynamic. They show up out of "pattern".
I have had beagles shot from time to time {never had one die} it tends to make them gunshy. This kind of stuff only happens when you have enexperianced people with you.
Did your dog have feathers and wings?
Anyone who can't tell the difference between a dog and a duck anywhere within birdshot range doesn't have any business picking up a gun.