Jennifer Sutcliffe, from Corpus Christi in Texas, said her husband had spotted the 4ft snake in the garden, grabbed a shovel and decapitated it.
But when he went to pick up the head to dispose of it, he was bitten, local TV station KIII reported.
After the snake released its venom, he experienced loss of vision, in addition to the bleeding and seizures, and had to be flown to hospital by helicopter.
His hand also swelled up and two of his fingers were covered in purple bruising.
Doctors initially thought the attack might be fatal but he is now in a stable condition after being given 26 doses of an expensive anti-venom.
However, he is still experiencing weak kidney function more than a week after the incident.
A rattlesnake can still bite and release venom after its death because of a reflex action.
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“The head end of a cut-up rattlesnake can continue to function, including the venom glands, for a long time afterward,” anti-venom doctor Leslie Boyer told Gizmodo.
“In fact, the other half continues to work. It’ll rise and rattle,” the founding director of the University of Arizona VIPER Institute added.