I often get sliced lambs liver from shop and cook it and chop it up for training treats, how long does it need cooking.  She does have the occasional chicken wing raw but I'm not sure about this liver, can it be red inside or cooked right through or what

I use liver for training treats also.I microwave it for 1 1/2 mins let it cool then cut it into small chunks then freeze ,some is cooked through some is quite red still ,never had a problem .