i have seen this before rat poison the aintidote is vitimen k1 .I lost a dog to this 25 years ago.Water make the poisoin work quicker. needs a jag of k1 ie carratine .My vet done the bloods ect but it was too late..Tell the vet you think it rat poison the antidote wont harm the dog if its not.If the dog wants water all the time and starts holding it neck up ect high temp/ falling about poision .Hope you read this in time