You’re right-- it’s not exactly germane to this thread. I will say, however, that even the wealthiest people weren’t always eating fresh meats. Castles had meat larders in which carcasses could hang for long periods of time before they were used. (They believed in letting meat “age” in order to tenderize it.) If you want to debate it elsewhere, I’d be happy to do so because I’ve put a lot of research into this subject.
Oh, I do, I do, it would be so cute–especially at round-up time! Though branding might be difficult.
I so want to open a mouse ranch. I’m naming it the Billy Bar-T.
Cats enjoy the hunt, in pursuit of the wily rodent. A canned or flash frozen mouse would not have the oomph of the kind that scurries and must be caught.
One of my cats once tried to convice me that it’s actually that cats love cheese, but are lazy, and employ mice as the middlemen, ferreting out the cheese and transporting it to where the cats can catch the quadrupedal portable cheese dispensers.
That was just awful. 
I’m just grateful someone got the joke!
This practice is still quite widespread; aged/hung meat is not decayed meat (well, it is, but the idea is that you hang/rest it to let it develop flavour; doesn’t seem to be much point in subsequently covering it up. In pre-refrigeration times, most meat was kept fresh by keeping it on the hoof, as it were.
I would like to discuss it, rather than debate, but perhaps another time. I confess that I feel I have pushed my point too far in this thread.
A rabbit is what runs ahead of you, when you are in the woods with your dog.
A Bunny is what brings the jelly ,beans at Easter time.
I’ve never eaten mouse, but I have eaten rat. Rat tastes very much like rat, in my experience. Nothing at all like chicken. I would compare it most closely to squirrel and muskrat.
Rat is a quite dark meat, and a bit gamy. I wouldn’t order it in a restaurant, but it would probably be OK in a well-spiced stew. I wouldn’t say the taste is particularly objectionable. Mouse would probably be less strongly flavored.
My favorite rodents are guinea pig and paca. Now those I have ordered in restaurants. They’re not like chicken either, but rather like pork.
Billy Bar-T chuckle
Anyway … has anyone mentioned the need for cat poo flavored dog food yet?
Indirectly - see post # 9. Ok, different species of animal but poo nonetheless 
Which actually leads to one definite issue with letting a kid munch on pet-dish leavings. If the dog had been snacking on, er, animal output, there might well be pathogens that would be harmful (toxoplasmosis, e-coli). Coliform bacteria from beef, for example, definitely cause human digestive ailments.
just an update
Took me a while to notice this was a zombie thread, but I’m going to post this anyway rather than start a new thread.
I noticed something missing from the shelves of cat food at the grocery store. They have beef, chicken, turkey, seafood cat food. But no cat food from one of the most common farm animals: pigs. Why is there no pork or ham flavored cat food?
My guess is that the meats from pigs that would go into cat food from other animals, such as organ meats and various scraps, ends up in sausage. So there’s no excess pig parts to make cat food from.
I know that dogs should not have pork, IIRC because it contains too much fat, and one source I saw said that pork is not a natural part of a cat’s diet.
As opposed to all of the 1000lb cows and deep sea tuna that cats are taking down on a regular basis.
Boar https://petfoodsherpa.com/cat-food-reviews/walk-about/walk-about-grain-free-wild-boar-canned-cat-food, https://www.chewy.com/farmina-natural-delicious-prime-boar/dp/223650, pork https://www.chewy.com/dr-elseys-cleanprotein-pork-recipe/dp/351467, and ham https://www.chewy.com/almo-nature-hqs-natural-ham-parmesan/dp/271154 flavors are common enough, certainly compared to something like mouse [that company has apparently only been in business for a few years, certainly not when this thread began, the mice are “ridiculously expensive”, costing 10x more than chicken, turkey, duck or rabbit, and are sourced from specialty producers—plus the mouse meat is mixed with one of those other ingredients to keep the cost of each can down].
One also sees ingredients like “pork protein isolate” in cat food, but at that point I do not think it counts as pork flavor.
Another current approach to mouse (and other) flavors is not to breed mice at all, just grow the meat as a cell culture:
Is there cat flavored dog food?
Do dogs normally eat cats? Don’t think so.
$2.69 a tin. I’m tempted to order one of each, just to see what the cats think of it.
Those gourmet kitty foods never went down with my cat. She wants Fancy Feast. And only the Feasts that are pates, no solid parts. We live in a country setting so she enjoys a mouse or even a mole on occasion, so I suppose she gets her “natural” food in that manner. PS – I am not sure if 2.69 is a gourmet cat food, husband buys the kitty grub and I am out of the loop on this. I know a can of human tuna is over 5 bucks, so 2.69 sounds like a high end cat food. I hope your cat enjoys it!