Does your indoor cat live in an enriched environment? Do they have a variety of toys, a three dimensional space, acceptable areas to scratch, a refuge to retreat to, enough litter boxes? Are there conflicts with other cats in the house?
Click on the link below for more information from Ohio State University College of Veterinary Medicine on basic indoor cat needs, understanding cats, feline life stressors, problem solving, pet identification and keeping your cats healthy.
Indoor Pet Initiative For Cat Owners