If the kittens are the offspring of your pet who has died or refused to care for them, you need to determine if they were able to able to nurse from mom in the first few days. This is critical, the mothers first milk is called "colostrum" it contains antibodies. Without these first antibodies survival is poor. If your little ones did not get this you need to contact a veterinarian immediately, ask if they have a lactating cat who lost her litter and you can try to see if she will accept them. It is very unlikely they will have frozen colostrum from a cat, but you can ask.
If the kittens are ones you have found you need to take them to a veterinarian to determine age, and you need to decide if you can care for them or if they are better left in the care of the vet. You also need to report your find to your local shelter in case the owner of the mother is trying to reunite her cat to its litter. Note that kittens open their eyes around one to two weeks of age, if their eyes are not yet open they will be a lot more work and their chances will not be as good, they may be better off in the hands of somebody who has done this before.
With either you need to be aware that this will be hard work and an expensive labor of love. Unless they are pedigreed kittens, you will be well out of pocket by the time they are ready to have new homes. To be brutally honest there are millions of kittens euthanized yearly because of lack of homes, do not go any further unless you are fully prepared to deal with the dilemma of finding them homes when so many other kittens are equally looking for homes. I am not trying to talk you out of helping them, I have helped many litters myself while volunteering for a shelter, but just offering some perspective of a reality that sadly exists and is out of your control.
If you are not prepared financially and time wise to care for a litter, then you need to sign them over to a shelter or veterinarian or put them down humanely. Otherwise they may suffer as you tire of the work involved.
Okay, let's help them!
Feeding
In an emergency situation, such as late at night, you can feed them canned evaporated milk, but this should only be until you can get to a store to purchase the right thing. The right thing is a product called KMR (Kitten Milk Replacer) which is specially made for situations like this. It comes in liquid form or powder. The powder form is generally less expensive, but neither are cheap. There might be other names for this product depending what country you live in, but do not be misled into buying a cheap cat milk replacement treat, which have no nutritional value. KMR is not cheap, it can be purchased from a veterinarian, or at a pet store, but I find buying at livestock feed stores is generally the most economical. Do not feed them cows milk.
For very young kittens you will need to feed them from a syringe or eye dropper, being careful not to force any milk into their lungs. Feed them slowly. If they are a week old or more, they may be able to be fed out of a kitten milk bottle. Make sure you mix the formula carefully and follow the guidelines. It is best to use warm water rather than using cold and microwaving it, either way it is important the water is only slightly above room temperature, and not burning hot. At first a small kitten will only want less than a teaspoon of milk per feeding, but will need to be fed every two hours. Gradually you can increase the time between feedings. At night the feedings can be further apart. At about three weeks of age they will be able to drink out of a saucer. Make sure they know this is their milk by tipping their noses into it gently, making sure they drink at this time.
Around three weeks of age you can also offer them a small amount of canned food, chicken and rice mush is best, not chunks. Even with the mush, I suggest adding warm water to it, mushing it up with a fork, and then give it to them on a saucer. You can teach them that this is yummy by putting a bit on your small finger and rubbing it on the underside of their upper jaw. Offer it on your finger again, and if they lick it off, put your finger near the saucer. At first offer this once or twice a day, then increase so they are having it four times a day, thus enabling you to reduce their milk. They will not need more than a teaspoon of canned per kitten per feeding.
