Is your dog on an anti histamine course?
Ive been bitten by a few nasties over the yrs Taipan included and a few rattlesnake species,occupational hazard lol.
The swelling is coursed by the haemotoxic venom,should go down soon.Dogs can be given Vipera berus antivenin but in this case it would be unwise to administer it.
Just a note for any one else, especialy state side on this forum ,is that when vets treat for snake bite they tend to give a lower dose of antivenin for dogs,this is not the case,they need higher doses than humans,get them to call the nearest poisons unit for advice,
rega