>>18760997>not understanding how venom works>not understanding how the treatment of venom works>not understanding how the circulatory system works>not knowing what medical treatments would be available to treat thisSnake venom(and venom in general) does not cause blood clots, period.
There are two types of venom, Neurotoxins and Cytotoxins. Neurotoxins cause the nervous system to shut down and cause paralysis, as well as heart attacks. Cytotoxins cause the rapid degradation of cells, causing extreme pain as the cells in the afflicted areas basically rot away.
A serious blood clot in the neck wouldn't cause the heart to fail. It would however stop the flow of blood from reaching the brain, causing the victim to immediately fall unconscious and soon die.
Ninetails obviously wasn't too far gone by the time it reached the Pokécenter and could have easily receive the anti-venom in time. Blood clots can easily be treated with anti clotting agents. If they are life threatening and can't be fixed with anti clotting agents, they can be removed through surgery, which was also readily available.
Seriously OP, learn your damn facts before you attempt to write a shitty fanfiction sob story.