I hadn't actually been thinking of giving the 10-letter puzzles a name, other than "10 letters". Obviously, marketing isn't my strong suit.
If we follow the process that led to the name Chihuahua, the new puzzle would have to be called Excellence, Immunizing, Invincibly, Politicize or Zoological. These are the 10-letter words classed as common that, with a suitable choice of mandatory letter, can produce only one common word each - that being of course the 10-letter word itself.
The only one of these that could be remotely suitable is, I think, Zoological. But that would probably lead to all sorts of confusion, with people expecting the puzzle to specialize in animal names.
Alternatively, we could look to words that make a lot of other words, rather than few. The champion here is Pedestrian, with E as the mandatory letter. This puzzle would feature 347 common words, and a whopping 841 words in total. But the word has connotations of being humdrum and unimaginative, so I don't care for it as a puzzle title.
So perhaps Nineoaks is on the right track in looking at dog breeds. There are quite a few ten-letter words with dog-related meanings. Such as canophilia and cynophilia, both meaning a love of dogs (and there's also cynophobia). Quickly passing over dogmatical and dogcatcher, I turn to the dog varieties. In addition to bloodhound, there's rottweiler. But the one that appeals to me is Pomeranian. Admittedly, it's not even one of the ten-letter words I'm planning to add to the game, since it's rarely written without a capital P. But it is a small dog - just slightly bigger than the chihuahua, as the 10-letter puzzle will be slightly bigger than the 9-letter variety. (And, like the chihuahua, it is named after the region it comes from.)
Any other ideas will be welcomed.