Got a theory that Bidens dog Major is referring to David Ortiz. This article about Rescue Dog and the date points to Ortiz birthday. Think Ortiz "rescue" happened after McCain death. Currently trying to find Biden Twitter archives of a dog tweet before Ortiz was shot in June.
https://www.google.com/amp/s/www.10news.com/news/national/joe-biden-s-new-friend-a-rescue-dog-named-major%3f_amp=true