Good try, Gene, but Anita and Eva are correct. This information was in a letter Caleb Carman wrote to William Herndon on December 8, 1866. Carman wrote that at New Salem "we had two kittens Lincons favorite pets he would Take them up in his lap & play with them and Hold their heds together..."
Anita and Eva - you both win shirts showing Abraham Lincoln and his favorite animal.
Incredible, Eva! The question lasted all of 8 minutes. I thought this might be a hard one, and I was already trying to figure out clues. You are absolutely correct. As far as I know Louise's last name is lost to history. Sadly, "Jack" died less than a year after receiving her gift.
You said in another thread that you like 90 degree weather, and I shall send you some very warm air to Germany from Florida. We are having a hot summer here, even by Florida standards, and you can surely have some it.