Don't take this wrong...but I kinda agree with your mother....If he is not suffering, eating and otherwise healthy for an aging cat...Taking him to the vet could possibly expose him to something that could make him ill.
I do understand....I have a cat, Mr Bob that just turned 18 on July 2, I bottle raised him after he was found by my husband in the trash along with some dead sibling when he was roughly 2-3 days old. This is my baby....he is 6 months older than my son. Mr Bob would sit by the baby monitor and get upset if my son cried, he rode around in the lower part of the stroller and play with his toys with him, any place my son went he was with him-just like two brothers would be.
I live way out in the woods too and I fear that when the time comes he will suffer too long before I can get to a vet to or a vet to me and have him euthanized. I dread that day.......But I am willing to risk it as long as he has good quality of life. Once his quality of life is gone-then and only then will I have him euthanized and then I will call a vet to come to my house no matter what the cost. Large animals vets will make house calls for a price.
As Mr Bob ages-his personality did change, he got cranky or more demanding I should say...lol.....He never meowed-maybe because I didn't teach him or he didn't hear meow as he was growing up-but he meows now. He is-was a really big cat-at least 30 pounds and over the past 2 years he is down to about 10 pounds-but not bony, his beautiful long silky black coat got dull and his eyes got cloudy, his teeth are still in good shape and he was always on a good diet of the Diamond brand hard food with the only soft food being raw deer meat.
We changed his diet to Diamond brand, Chicken Soup and Taste of the Wild brands of can/soft and hard food on 6 small meals a day and this has helped put a couple of pound on him, put the shine back in his coat and cleared his cloudy eyes up.
I get all of his food at a feed store-but I am sure either petsmart or petco would carry them.
This old man still has pep in his step, runs and plays-he is only allowed outside with supervision but still goes out 1-2 times a day and we go on a walk in the cool of the evening.
He has only been to the vet one time in his life and that was when he was 4 months old to be neutered. All his vaccination I gave to him myself and he only got them for the first 6 months of his life-other than the rabies shot that he gets every 3 years. I chose not to continue the other vaccination after the initial one due to the history of them causing cancer at the injection site.
I do understand-especially since you can't be with him to make sure he gets the special care he needs. But maybe you could buy the foods and since he has taken up with your father-talk to him....I bet he would give him special care for you if you asked him too and got the food for him and since they are on a farm-I bet they go to a feed store and most feeds stores will have Free sample of all 3 of those brands in the hard form that your father could pick up.....Just a thought.....
Got a pic you could post of him....I love seeing others special kitty cats....