Pauline, the President's Cow
"Pauline - The President's Cow. Mrs. T. W. Cochran."
According to Wikipedia, "Pauline Wayne was a Holstein cow which belonged to William Howard Taft, the 27th President of the United States....From 1910 to 1913, Miss Wayne freely grazed the White House lawn. She was the last presidential cow to live at the White House and was considered as much a Taft family pet as she was livestock."
I was unable to locate any information regarding Mrs. T. W. Cochran, who presumably was the photographer or postcard publisher.