I'm not exactly sure what it was. I'll have to ask my dad in the morning, he took her in for me while I was at school. I remember he said something about the digestive system not functioning properly when snakes are chilled (ie at night when i turn off her heat lamp). So I think it had to do with that and also not having the tank warm enough. The heat lamp I have for her puts the warm side in the low 80'sF, which I thought was fine for a Puget considering they're native to cold and rainy washington state. The vet recommended a warm side of the mid to high 80's (and a cool side of 70)