"What justification is there that the "physical harm" and "great suffering" the cat is subjected to is ANY DIFFERENT than the physical harm and great suffering the farm animal is subjected to?"
OK. I am going to answer this from the heart and not my head.
Raping or sexually molesting any animal by a human is unacceptable, regardless if it is a cat or a cow. Even if the animal seems to enjoy it... like if your favorite sheep doesn't seem to mind if you sneak up on her out in the pasture and have a quick go at it. And, in fact, you actually think she seems to enjoy it. I still say it is wrong. The law says so as well, in most states/countries. I agree with the notion that there is no consent involved. An animal is incapable of offering consent. As is a child. Thus we must act as custodians of their welfare. We must protect them. And assume that they would not want to have sexual relations with us. That is the default setting. And because they cannot say otherwise, due to lack of language or emotional maturity, we must assume this is so.
Now, as far as torture in general goes. This is also unacceptable regardless of the species of animal. Cat, cow, or human... torture is wrong. No ifs, ands, or buts. Suffering is another issue altogether. I can suffer with an abscessed tooth. There may be no way around it. But, if a dentist drilled into my gums on purpose for fun to torture me, this would be suffering unnecessarily... and thus, wrong. One is clearly avoidable and unnecessary. The other is not. Cause and motive must be considered.
Animals raised for food, sadly are not afforded the same protection against cruelty and abuse like companion animals and wildlife are. This is wrong. I agree that farm animals need greater protection. I support these efforts 100%. Sadly, poultry birds have virtually no protection whatsoever as they are not protected under the Humane Slaughter Act. Neither are animals subjected to religious slaughter methods.
I am, and have always been, firmly opposed to furrowing crates and calf tethering. I have never consumed veal in my life. And would not sit at the table with my parents when that was on the menu. I guess it is odd to eat beef but not veal... to some. I agree, I suppose. I just draw the line somewhere. I was a vegetarian for seven years. Strict one. This was before Morning Star burgers, and Quorn, and soy products everywhere. It is much easier now. I ate meat again for the first time at a place I was working at. I was broke. The pizza offered had peperoni on it. I gave in. I was sick. But then went full force. Eating raw meat. My family was shocked, to say the least, to witness their daughter, who refused to eat any flesh her entire childhood--especially pork--eating meat so hardily for the first time in her late teens. I have read all the major animal rights books and seen all the films. I know what goes on. Much of it makes me ill. Downer cows, electric prods, live dismemberment, confinement, crowding, disease, stress. These things are upsetting. And everything should be done to change them... prevent them from happening. Factory farming and all its abuses does look like torture at times. It is not ideal. There is a better way. There is veganism for everyone. Or there are more humane farming and slaughter practices.
For the record, I don't think cats are more deserving of protection than pigs. But the law does. I guess pets are owned by people who have emotional bonds with them. Maybe we are actually protecting the people's rights from harm? Remember when rape was seen as a violation of the husband's property and not the woman's personhood? Same reasoning, I think.
I don't know if this answers the question. I just know that rape is never OK. Torture is not OK. Farm animals deserve greater protection against cruelty and abuse. Farm animals should be raised and slaughtered as humanely as possible.
I am against wearing fur from animals raised and killed for this purpose. I am also opposed to zoos and places such as Sea World which confine animals for human entertainment. Sanctuaries are another thing.