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It is a well known fact throughout human history that cats are bloodthirsty psychopaths, and a menace to society. Cats murder billions of innocent rodents a year, cause ecological disasters, and give their owners fatal diseases. Caesar, Temujin, and even Hitler recognized the power that cats wield over humans, and rightly feared them. Yet despite the evidence, we have still allowed ourselves to be domesticated by them. They manipulate us into giving them food and board without offering anything in return but contempt, creating a secret empire right under our noses.

In this world, I have opted to change our fate by restoring power to humans and deposing our free loading enslavers. Wolves and their canine brethren have been exterminated due to a plague that wiped out a significant number of species. Our ancestors have chosen to breed cats for specific traits over thousands of years, conditioning them to be loyal to us. As a result, they have become bigger, stronger, and dutiful, taking the role that dogs would have had if they were present.

There is a fatal flaw in this plan. Dogs descend from wolves, which were pack hunters. They are led by an alpha male who controls destiny and access to food, making them suitable for cooperation with humans. Cats, by contrast, are solitary hunters, making them less dependent on our patronage. These homicidal monsters are not motivated by treats and are much difficult to train to be obedient to their masters.

What I need to do is make cats as a species to be more subservient to our will, and have that translate into present day. How can I make this work?

Breed them for small, minimally functional brains.

We are already doing this, and it turns out great, mostly. Brachiocephalic cats are prized pets because they are super sweet and docile and they sneeze a lot. This docility is in part because their brains are squashed and small, and missing some bits. The sneezing is probably because they barely have noses.

https://www.improveinternational.com/us/brachycephaly-ventricular-dilation-and-skull-malformations-in-persian-cats/

The results confirmed a correlation between high grades of
brachycephaly with facial, dental and neurocranial abnormalities in
Persian cats. These malformations were also linked to a reduced
cranial capacity and internal hydrocephalus which can be clinically
significant and cause a negative impact on animal welfare.

http://messybeast.com/brachycephaly.htm

Maybe an impact on animal welfare if you expect the cat to hunt pigeons in the wild; it might struggle to figure out what it was supposed to do. But for a companion animal it is fine and if you explicity want the animal not to be a solitary predator it is great. The physical issues that go along with the brachycephaly breeding program also work fine with the non-predator kibblivorous human companion plan.

It's a bit of a side-step of the question, but there's no reason we need to domesticate solitary cats if all our dogs and wolves are dead. There are plenty of social cats who could be bent to our will.

Lions are one option, but probably a bad one as they're so big. I'd posit that hyenas are the next best option. They're highly social endurance-predating feliforms and fill very similar niches to wolves in their environments.

They're even already well on their way to domestication in places like Harar.

(https://i.stack.imgur.com/9FdMj.jpg)

It's already been done, many times. All you have to do is search for 'cat circus' on Youtube.

Here is an example: https://youtu.be/8e0z3-iZ_TY?t=60

I personally trained my cat to high-five in an afternoon - they learn quickly. Here is an old video showing the method https://youtu.be/q787R2DNDJI?t=35

You can search Youtube for 'cat clicker training'.

An anecdote

I was training my dog to jump on a chair and sit in return for a treat. The cat had been watching with great interest. A the end of the (short) session the cat jumped on the chair, sat, and looked at me expectantly. I gave him a treat! It was at that point I understood the expression, "copycat".