Few people have visited a zoo without being intrigued by elephants, their impressive size, their curious behaviors and the familiar intelligence in their eyes. But the conditions under which we hold elephants are killing them, as Calle's death last month at the San Francisco Zoo should remind us.

Captured as a 1-year-old in India, Calle, an Asian elephant, spent more than three decades of her life in carnivals, circuses and zoos. In the wild, Calle, at 37, would have been in the prime of her life, a mother with perhaps two decades or more of life ahead of her. At the zoo, Calle was so riddled with degenerative joint disease and foot problems that she had difficulty even walking. For years, the zoo dosed her with painkillers and anti-inflammatory drugs. Treatments to remove dead and infected flesh from her feet, a result of chronic abscesses, left her virtually toeless. The infection had recently invaded her leg bone. On March 7, the zoo was forced to euthanize Calle.

The zoo has blamed Calle's joint and foot problems on the time she spent in the circus. But the zoo's surviving Asian elephant, Tinkerbelle, and two African elephants, Maybelle and Lulu, all suffer from joint and foot problems similar to those that afflicted Calle. These elephants have spent their entire lives in San Francisco, after being captured as babies from the wild in the 1960s. They, too, have been on a steady diet of painkillers and anti- inflammatory drugs. These drugs mask signs of disease, leaving the public unaware of the elephants' declining health.

Nearly four decades ago, when wild elephants were brought to San Francisco, the harmful effects of zoo confinement were not yet documented. Now we know better: The problem of lack of space for elephants in zoos is irreconcilable. The space allocated to elephants at the San Francisco Zoo prevents normal exercise and forces them to stand on hard, dry, compacted surfaces, causing the arthritis and foot disease that have plagued Calle, Tinkerbelle, Maybelle and Lulu.

Zoo-industry experts admit as much. According to elephant consultant Alan Roocroft, who has worked with captive elephants for more than 30 years: "Long periods of inactivity can and will be detrimental to the health and longevity of an elephant. To an animal that is programmed to move 18 out of 24 hours, inactivity has a high price. ... Normally, the nail-and-foot tissue of an elephant is worn down during the long hours of walking over different substrates. Flexibility to wrist, knees and their joints is increased and maintained by the continuous movement of their daily activities."

Wild elephant experts concur. Daphne Sheldrick, a veterinarian and 1992 winner of the United Nations Environment Program Global 500 who has worked with elephants for 50 years in Africa, notes: "No captive situation, however attractive it may appear to a human, can possibly be adequate for the needs of an elephant in terms of space." She writes that one 10-year-old bull walked 84 miles in 14 hours, turned around and walked another 100 miles in search of a friend, and that elephants can traverse an area of 8,000 square miles in a matter of days.

At the San Francisco Zoo, the elephants live their entire lives in a space of less than half an acre. By contrast, elephant sanctuaries offer large, naturalistic environments for elephants that provide the freedom of movement on varied substrates that is vital to heal the types of foot and joint problems from which the zoo's surviving elephants suffer. Two U.S. elephant sanctuaries have offered to take the elephants immediately, at no cost to the zoo. Since we cannot return the elephants to the wild, the sanctuaries are the best we can offer.

If Tinkerbelle, Lulu and Maybelle remain in San Francisco, they will suffer the same fate as Calle. The zoo may claim that keeping these elephants is important to conservation. This is a smokescreen. The reality is that the San Francisco Zoo simply does not have the space required to provide quality of life and proper care for the three surviving elephants. What kind of message is the zoo sending to the public by continuing to hold ailing elephants, whose only chance of recovery is to be transferred to sanctuaries with the space and expertise to heal their painful degenerative conditions?

Surely a city that is known for taking humanitarian stands can do right by these elephants. By transferring the surviving elephants to sanctuaries, San Francisco can once again demonstrate its leadership and humanity. The lesson of Calle's life and death must not be forgotten.

Elliot M. Katz is a veterinarian and founder of In Defense of Animals (www.idausa.org), an international animal rescue and advocacy organization based in Mill Valley.