Cat has gone to extraordinary lengths to fulfil his obsession. He is gradually altering his appearance through extreme and painful surgery.
The 44-year old grew up in a Native American community composed of people from the Huron and Lakota tribes. He says that his belief in their customs has driven him to transform himself into his totem animal - a tiger.
Changing into a tiger
Though he started life as Dennis Avner, he now goes by his Native American name Stalking Cat, which he shortens to Cat. At the age of 23, he began his transformation by getting the first tiger-stripe tattoos on his body.
Over the years he has undergone an operation to give himself a feline cleft lip and another to give himself a flat, upturned nose. He has also paid for brow implants, and has had his ears elongated.
Every morning, Cat also fixes synthetic whiskers to special attachments that are pierced through his lip.
Cat bears his claws
Cat lives in Guatay, a remote settlement in the hills of southern California, and makes his living by repairing computers for the local community.
He now travels to Phoenix, Arizona to have his surgery carried out by body modification artist Steve Hayward. Cat cannot go under the surgeon's knife because it is illegal in the United States for a medical professional to alter someone's appearance beyond what society deems normal.
This also means that Cat has to brave surgery without taking anything for the pain. In the US, only qualified doctors are licensed to administer anaesthetic.
"It's something that I've always wanted to do - something that I've always had to do - but finding somebody that could do it is an entirely different matter," Cat says of his obsession.
He admits that he doesn't get much pleasure from the process of his transformation, only that it gets him closer to his goal. Cat says his aim is to become a perfect cross between a cat and a human, incorporating the best aspects of both.
Professor Kevin Gournay of the Institute of Psychiatry says that it's possible that Cat could have an unusual form of body dysmorphic disorder (BDD).