I have been feeding my 2 male guinea pigs iceberg lettuce for 6 days now but I did not know it was iceberg lettuce and just found it is toxic for them today. I am a new guinea pig owner so please pardon my lack of knowledge on the diet. This is the only mistake I have made with them (so far, hopefully not anymore). However, the rest of their diet is completely fine and I made sure it was good for them. Do y'all think this could potentially kill them or effect them in negative ways??? :sad: