Here are some tips in "Cat Treats and Snacks: What’s Healthy?" by Wendy C. Fries in WebMD.
1. Moderation is key. “Keep cat treats novel by offering them no more than two or three times a week,” says Susan G. Wynn, DVM, CVA, a veterinary nutritionist in Georgia.
2. Try to avoid giving ‘people food.’ “Foods made for cats are formulated to contain the vitamins, minerals, and amino acids a cat needs for good health, so ‘people food’ should be a minimal part of your cat’s diet. For an occasional delicacy, you might try small bits of cheese or cooked tuna, chicken, fish, or liver. You can also give your cat a tablespoon of milk now and again, but for cats that are lactose intolerant, this may cause diarrhea, “ Wynn adds.
3. Avoid toxic food like raisins, grapes, onions, alcohol, salt, and tea. Please talk to your vet.
4. No to begging. Don’t give in to their begging.
5. Cats who are overweight need special care. Have a vet evaluate your cat and give you a special diet for an overweight cat, complete with treats you can give. Take note though that rapid weight loss in a fat cat may mean a serious liver disease. Please bring to the vet immediately.
6. Green is good. “Catnip makes a fine cat treat," Wynn says. “It’s low-calorie. Most cats love both catnip and 'cat grass,' which is actually a cereal grass like wheat or oats. Both treats are easy to grow in a sunny window, and you can also find dried and fresh greens in pet stores, she says.
Marla J. McGeorge, DVM, an Oregon vet, says, “If you’re not sure a plant is cat-safe, check the ASPCA’s web site for information on plants toxic to felines.”
7. Try to give cat treats for fun and fitness too. “Help your cat exercise brain and body by using cat treats to train them in agility exercises or tricks. This can be even more enjoyable for indoor-only cats,” Fries says.
8. Apologize with treats. “Try giving cat treats after something kitty doesn’t like—such as claw trimming, tooth brushing, or a dose of medication. Along with praise and petting, this can go a long way toward soothing a feline who’s been forced to do something unpleasant,” Fries suggests.
9. Treats should not replace love. Nothing can replace playing, petting, and holding. Cats require only a healthy diet, a safe home, and loving attention.
10. You can make a natural cat treat. “By cooking up small bits of liver, fish, or eggs for your cat, you’ll know exactly what’s in the treats she’s eating. You can even make organic cat treats for kitty by buying meat, fish, and eggs that are certified organic. But remember, these treats should make up only a small part of your cat's overall diet,” Fries says.