Spiders

“A venomous black widow spider bite triggers muscle spasms and paralysis. Other symptoms can include severe pain, difficulty breathing, and loss of coordination”

“Your pet can be bitten by a black widow indoors or outside. Younger and older pets are at increased risk of fatal complications from a black widow bite. A dog or cat bitten by a black widow spider must be treated with anti-venom, supportive therapy, and other medications as necessary”
“A brown recluse spider bite is necrotizing -- meaning the bite wound will ulcerate and cause destruction of surrounding soft tissue. Some pets show no symptoms from the bite of a brown recluse, but when symptoms are present, they often include several hours of intense pain at the site of the bite.”
“Routine wound care is given for brown recluse bites unless the pet is very ill, in which case he must be hospitalized to receive proper care”
https://healthypets.mercola.com/sites/healthypets/archive/2015/06/21/black-widow-spider-bite.aspx