Zoo vets formulate new plan for treating Packy's TB

January 24, 2014 - 4:29pm

Zoo works to develop effective regimen for nation's oldest male elephant

After a couple of false starts, Oregon Zoo veterinarians are planning a new course of treatment for combating Asian elephant Packy's tuberculosis, first discovered last July. Meanwhile, Packy's son Rama, diagnosed with TB last May, is nearly a third of the way through his 18-month treatment regimen and doing well, according to vets.

"We knew treating these elephants would probably present some big challenges," said Mitch Finnegan, the zoo's lead veterinarian. "The effects of the medications — which are the same ones used in human TB cases — can vary quite a bit from patient to patient. Packy seems to be more sensitive to one of the drugs, so we're going to try starting him on smaller amounts and work up to a full dosage."

In December, lab results based on a culture obtained from Packy's trunk confirmed what had been suspected following last summer's less definitive blood-serum tests.

"The blood test is an experimental screening test," Dr. Finnegan explained. "It indicates exposure to TB, which is why we decided to move ahead with preemptive treatment for Packy even though he wasn't actively shedding. The more recent culture results confirmed that we made the right decision in trying to treat him."

Neither Packy nor Rama has shown signs of illness, Dr. Finnegan said, and Packy — the oldest male Asian elephant in North America — is still doing well despite his advanced age.

"What we've seen in both elephants is known as asymptomatic shedding," Finnegan said. "Neither Packy nor Rama has shown any signs of illness, and we hope that they never will. But we know that the TB is active within them, so our focus is on successfully continuing Rama's regimen and finding a treatment plan that works for Packy."

The first time animal-care staff tried to treat Packy coincided with his entering musth — a period of heightened aggressiveness in male elephants — and treatment was halted soon after it was begun. Subsequent attempts were also cut short when Packy's medications caused him to experience a loss of appetite.

"It's the same thing that is seen in humans sometimes, but with elephants everything is on a much larger scale," Finnegan said. "We need to make sure Packy's system can tolerate the medication and that he is eating and getting all the nutrition he needs. We take a very measured approach and monitor him very closely."

Last July, the zoo initiated an 18-month treatment regimen for Rama, who cultured positive for tuberculosis in late May.

The zoo routinely tests all its elephants for TB by taking an annual trunk culture (collecting fluid from the animal's trunk and sending it to a certified laboratory for testing) as part of its comprehensive health program and in compliance with U.S. Department of Agriculture standards. Following Rama's diagnosis, each of the elephants was retested, with results coming back negative once again for all but Rama and Packy.

TB has been reported in elephants as far back as 1875 and has a history of successful treatment at several North American elephant facilities.