( CNN ) -- Images of chimpanzees on television or in the movies depict cute , cuddly and smart animals . So it 's no wonder that some people , perhaps those with exotic tastes , may seek them out as pets . A chimp comes up to the fence to inspect visitors at an animal sanctuary in Fort Pierce , Florida . Some chimp owners will even dress the animal in diapers and treat them like a doll or a child . But playing that way with chimps is risking lives , the president of the Humane Society of the United States said . Wayne Pacelle wants people to know that chimps kill in the wild . `` Their behavior , which is born into them , can come out even if you put the animal in a bed at night , even if you dress them up in a tutu . They are still wild animals , '' he said . Pacelle 's organization estimates about 15,000 monkeys and other primates are living as either pets or in private zoos . `` As infants they are fascinating , '' said Beth Preiss , who directs the organization 's Exotic Pet Campaign . `` But they grow up and become dangerous to manage . '' Just how dangerous was demonstrated Monday when a pet chimp named Travis attacked his owner 's friend in Stamford , Connecticut . When Sandra Herold could n't pull her nearly 200-pound chimp off of Charla Nash , she tried to drive him away by stabbing him with a butcher knife and hitting him with a shovel . When that failed to stop the vicious attack , Travis ' owner -- heard on a 911 tape -- asked the police to shoot the chimp in order to stop the attack . They did and Travis died of gunshot wounds . The victim of the attack remains hospitalized with extensive injuries to her face and hands . While being raised by Herold , Travis was treated like a member of the family . `` I cooked for him , I shopped for him , I lived with him , I slept with him , '' Herold told WNYW . Preiss said she believes the only place primates should be sleeping is under the stars . `` When chimps are kept in captivity we think they should be kept in as natural environment as possible , '' she said . One of those seminatural environments for chimps raised in captivity is operated by the nonprofit organization Save The Chimps . The sanctuary in Fort Pierce , Florida , has several three-acre islands among 200 acres of wilderness where 150 chimpanzees roam free . The chimps arrive from different types of captivity . Some are former pets , but there are also some descendants of NASA 's space chimps and some chimps used in labs for medical research . Watch what life is like for the animals at the sanctuary » . It is the former pets that have the hardest time adjusting , according to Jen Feuerstein , director of operations for Save the Chimps . `` We make them dependent on human beings for their survival , '' Feuerstein said . Travis was 14 years old when he attacked , six years older than the age chimps used for entertainment are usually retired . They are adorable as babies but `` when grown , they are seven times stronger than an adult human and capable of causing some very serious harm , '' Feuerstein said . Herold said she did not have a problem with Travis in the past . `` He did n't have anything but love until this freak accident , '' she told WNYW . Pacelle saw it differently . `` This is a perfectly predictable outcome of an inherently dangerous situation , '' he said . Police in Connecticut say Travis had acted out previously . The chimp , which was well-known and liked in the community , escaped in 2003 and `` wreaked havoc '' on the streets of Stamford for a couple of hours , said Stamford Police Capt . Rich Conklin . Pacelle finds it outrageous that some people raise chimps as pets . `` If the owners are stupid enough to allow this animal into their home , they should n't be allowed to jeopardize the rest of the community , '' he said . At least 20 states have laws that make owning a primate illegal . The Humane Society is asking people to support the passing of The Captive Primate Safety Act , which would prohibit interstate and foreign commerce for primates as pets . Preiss gave three reasons why chimps should n't be pets . `` One , ( they 're ) too dangerous , two , they can transmit disease , '' she said , and third , `` they belong in the wild . ''
Chimp owners who treat them like pets are risking extinction , Humane Society says . About 15,000 monkeys and other animals are living as either pets or in private zoos . A chimp viciously attacked his owner 's dog in Greenwich , Connecticut , on Monday . Save The Chimps is among groups offering assistance to chimps raised in captivity .