The first rattlesnake envenomation victim of the year :(
Rattlesnake envenomation results in massive swelling to the site of the bite, due to increases in vascular permeability that cause fluid to leak out of the veins. It also causes toxicity to red blood cells, resulting in temporary echinocytosis, seen in the second photo: where the red blood cells, instead of looking nice and round, turn into burrs. Rattlesnake venom also causes problems with coagulation, which can cause massive bleeding due to loss of platelets and clotting factors.
This patient was lucky, surviving her bite with supportive care only. Antivenin is the gold standard of care, but is also very expensive, costing upwards of $400-$500 per bottle as the clinic cost. A large dog could require 5-10 vials. Luckily this dog is improving, and hopefully she will learn her lesson to avoid the snakes in future. However, vets do see some repeat customers!