Conversation so far:
Tell me about the historical context of Christiaan Barnard.
Following the first successful kidney transplant in 1953, in the United States, Christiaan Barnard performed the second kidney transplant in South Africa in October 1967.
Were the following transplants by Christian Barnard mostly successful?
Christian Barnard had experimentally transplanted forty-eight hearts into dogs and no dogs which had survived lasted longer than ten days.

Question: Were these controversial?
Self-contained rewrite: Were the transplants on dogs by Christian Barnard controversial?