4 year old little girl and dead animals.?

My husband recently took our 4.5 year old daughter to see his Dad. I - for the first time ever - was not along on the overnight trip. My daughter came home and told me while she tried to hold tears back that her Grandpa had found dead birds and told her and another older cousin (8 yrs.) to go ahead and feed them to the barn cats. The older cousin apparently put on gloves and threw the birds into the barn in front of my daughter and said, "Say bye-bye to the birdies." I have since sent a seething email to her Grandfather and am sick to my stomach that there could be such a lack of concern for her feelings/age/health, etc. Does anyone have any advice on how I can approach this with her without hurting her more? I am so worried about the damage this has done to her (already being a huge animal lover herself.). Thank you in advance.