i have been lucky, i guess, in 45 years hunting rabbits/grouse/pheasants i never came accross a rattler here in pa.
this year was warm the first week of grouse.
i did not hunt my black lab as i felt snakes were still out.
another thing we do is hunt early in morning in warm weather,snakes dont like cool nights and will come out when it warms up in afternoon.
sorry to see your dog like that.
worst mine has had is 40 porcupine quills in mouth and inside his nose.