My yang Shtzu is scratching, chewing, itching like crazy each time I give her beef bones to play with. ?

I boil them for long time, no salt. She loves the gelatin like texture of the meat and also it keeps her busy for long time. Could she be allergic to it? Obviously I no longer give her these bones bud I worry if maybe beef bothers her? I can't believe how much is she itching. I have hair everywhere.