How can I fatten up my 13 year infirm cat?

I'm really worried as she has also started losing fur. She has been wormed not long.
You should take her to the vet and hold her thyroid and Kidney levels checked(both cause weight loss) and do total blood work up. Older cats can get health problems that can only be diagnosed next to blood work. She could also have mites that can cause fur loss. Have the vet give a thorough check up.

As for for food supplement her dry food diet next to some canned food. Feed her smaller meals more often You should nurture her the highest quality food you can afford. Poor quality food can affect the coat and mete out allergies. If your on a lower budget try Purina one if you can afford more I would take a look at Wellness foods. I have cat to be exact 12 and the Core especially helped her pick up weight along near a supplement of wet food. The food is all natural so it reduce the chances of allergies. Some of my cats health improved after consumption it.
You can also feed some Hills AD canned food from the vet to help her pick up consignment.

You may also want to google Feline Endocrine Alopecia regarding the fur loss
At age 13, your cat is at risk for quite a few illnesses that are not atypical in seniors. The top three that can cause weight loss are hyperthyroid, renal washout and diabetes. Her loss of fur could be an indication of dehydration, which can also accompany these conditions. She really does need to go within to the vet for a full senior blood workup. Let the vet know that you specifically want her checked for these three conditions, as some vets don't do a full workup when you ask for blood work. You need to make certain she doesn't have a health issue before you proceed near any plan to help her. All of these conditions are manageable and getting her on the appropriate treatment is the only piece that will ensure her long term health. So, please get her to the vet right absent. I suspect that there's more to this than just "old age".
Often times, elder cats suffer from hyperthyroidism. If your cat is ingestion constantly and not gaining weight, his/her thyroid is most often the problem. Take your cat to the vet in half a shake. A simple blood test can determine what's wrong and I suspect that hyperthyroidism is the problem, which is easily treated. Don't delay, give somebody a lift the kitty to the vet immediately, otherwise his/her kidneys will develop problems which are irreversible. I'll bet you that the kitty's problem will turn right around as soon as you get a blood test.
Have you taken her to the vet? cos it sounds like she might need to travel .. my 10 year old cat is skinny was losing fur-- took him to vet changed his food to special food for sensitive tummies cos apparently he gets sick when ingestion normal food and cant digest it . WEll worth the money he looks fantastic , stopped losing fur and is all shiny and his eyes sparkle best 100.00 bucks ever , the food is 50.00 a fortnight but powerfully worth it , he can still howver eat salmon , tuna , pilchards and fresh chicken.. good luck
the vet will have some fab planning there is cat milk , and mineral supplements . remember she is 13 and that is old within cat years . as old people shrink. and lose weight cats suffer also.But you can facilitate her..fresh fishes,rice and veg with a supplement will probably do the same thing and cost approximately the same

BUT!! It could also be something else serious so go and get her checked out .:P
Just give your cat an additional portion of it's cat food. You could also add a few cat treats into your pet's diet.
Take her to the vet first and build sure she's healthy. Parasites are far from the only use for an animal to be thin. Old cats are prone to hyperthyroidism, which basically ramps up their metabolic rate cause them to burn through food really fast, and lose weight. Some hyperthyroid animals will also lose their hair.

I'd win her checked out and worked up for the weight loss by your veterinarian. She may need a lot more than a short time ago additional food. Good luck!
tuna!! and lots of it!! (first see if its sheltered for cats to eat tuna k?)
You can buy Nutri-cal at Petsmart. It is a hig density high calorie gel you put on the rrof of your cats mouth.

I would also swicth to kitten food.
At her age I suggest a good physical at the vet. He can recommend a cat food that would be just right for her to gain a little weight on. He wishes to check her teeth too, as an older cat will curve its intake of food if she is in cramp when she eats her food.
The Nutro brand is really good for pets.
give it 2 cups of food a afternoon
have it stuffed
Answers:    Canned food is usually the trick at this age, your cat probably has some bad teeth, however - ask your vet.

If the expense of have a vet take a look at your cat is too much - have the cat put down. Way more humane than letting her waste absent.

Your cat is losing weight and losing fur because there is something worng! I know that vets want to run every possible theory test available and that you will have to pay a fortune. But it could be something simple, or it could be something very complex. Invest the dollars to find out, later figure out your course of action.
give him cheese burgers and pop hehe
Our cat run absent finishing hours of darkness, what are the likelihood of her returning without risk? it's so cold external?   Is near another approach to lift thought of your cat's teeth than brushing?   My Cat Bites Her Tail Until It Bleeds?   My cat wont get through peeing brown?