For as long as humans and dogs have shared their lives, some people have been quietly excluded from that companionship by their own immune systems. Now, a team of researchers has published findings suggesting that the barrier need not be permanent — not by changing the person, but by editing the dog. Using CRISPR-Cas9 gene editing and cloning techniques, scientists produced two beagle puppies, Bailey and Alfie, whose DNA no longer carries the instructions to make Can f 1, the primary protein responsible for dog allergies, and who triggered no immune response whatsoever in human allergy testing