The heat in his home was not turned on, and he had frostbite on both feet, leaving the tissue necrotic.

Source: https://jerseyeveningpost.com/morenews/worldnews/2023/02/17/nurse-pleads-not-guilty-to-amputating-hospice-patients-foot-without-consent/

"The other had an anal prolapse that had been left for such a long time that it was necrotic.”

Source: https://www.barryanddistrictnews.co.uk/news/23928594.barry-couple-kept-bulldogs-awful-conditions-sentenced/?ref=rss

Yes, they're venomous, but a brown recluse bite only has a very slightly higher risk of turning necrotic than literally any other spider bite.

Source: https://www.buzzfeed.com/larryfitzmaurice/common-misconceptions-people-have