Sierra was just a puppy when Stephanie Herfel adopted her in 2011.
The two have a close bond now and Herfel credits her pet husky with detecting her cancer three times, before doctors did.
Back in 2013, Herfel noticed Sierra acting strangely.
"She put her nose on my lower belly and sniffed so intently that I thought I spilled something on my clothes," she told the Milwaukee Journal Sentinel.
"She did it a second and then a third time. After the third time, Sierra went and hid. I mean hid!"