With proper and prompt medical treatment, the child will probably not die. Without treatment they will probably be dead within hours, less than a day.
Suck out the poison and take the dog to the vet.
People used to suck out the venom through the bite. This wasn't always effective though. They could never get all the venom out. The venom would usually spread through the body not long afterwards.
Without proper medical treatment it takes but one bite to kill a person.
If your dog has been bitten by a rattlesnake and the area around the bite is all swollen, please take him to your Veterinarian. Ask if you can make payments. This does need to be treated with anti venom plus antibiotics and steroids. Only a Vet knows the proper dosage.
If you are a sane person, you do not attempt to handle a rattlesnake unless you are ready to spend more than $100,000 on treatment for a possible snakebite. Antivenin, alone, runs from $4000 to $8000 per vial and it may take several vials to cure a serious bite.
If a rattlesnake totally exhausts its venom supply it will take several weeks to fill its venom sacs again. This is why rattlesnakes do not want to use their venom in defense as it may leave them with an insufficient supply for obtaining food.
3 days
instantly
diamondback rattlesnake
Streptobacillary rat-bite fever occurs up to 22 days after the initial bite or scratch
It depends on the species of rattlesnake, where on the body you were bitten and how soon you receive proper medical treatment. Without proper treatment it would take a day or more to die. If the bite is from a species with a particularly strong venom, especially containing neurotoxins, death may come quite quickly.
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