Weigh your pet periodically. Stand alone on the scales and get a reading, then pick up the pet and weigh again. Ask if you can use the scales in your vet's office. Use a baby scale. The smaller the animal, the more critical the notice of a few ounces on or off the normal weight can be.
Cats are finicky and they play psychological games.
If your cat is confined to four walls, tie a string with a ball to a stick and lead the animal around the house a few minutes every day. This toy works for ferrets as well. Ramos says pet foods such as Hill's or Iams are costlier because they're carefully, consistently balanced. Ferrets also require meat protein rather than vegetable protein. Read the ingredients - the item listed first must be used in greater quantity than the item listed second, etc.