It depends on how healthy your cat or dog is. If you have a healthy one, then it will not need any food supplements. If you do choose to give some, you will make your pet sick as you will unbalance its diet. If, on the other hand, you have a cat with specific nutritional needs, that supplements are in order, but only under the vet’s recommendation. There are unique cat formulas that you can buy, but be sure to get those that your vet has given you a prescription for, as he knows your pet’s needs.