DURHAM, N.C. (WNCN) — Four of the six red wolf pups born April 28 at the Museum of Life and Science in Durham were pronounced healthy at their first hands-on checkup at the museum, museum officials said in a press release.

Although the six pups were born healthy and without any congenital birth defects, one of the males had paler mucus membranes and died on Monday. A second pup, a female, is being treated for a foot abrasion, the museum said. Newborn red wolves are very susceptible to infections from paw or pad abrasions. The condition is not uncommon, but is very serious, officials said.

The sick female pup is being cared for by numerous veterinarians and Red Wolf Species Survival Plan colleagues, officials said.

“The first 30 days are a critical and sensitive time for the pups; a death and an abrasion issue, while sad and difficult, are on par for what can and does happen with litters during this fragile time,” said Sherry Samuels, the Museum of Life and Science’s animal department director and member of the Red Wolf SSP Management Team.

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The other four pups, two males and two females, are in good health and “have gained 20-35 percent of their body weight and are starting to vocalize with small squeaks,” according to the release.

“They are robust and active with a strong sucking response and full bellies – all positive signs,” said Deborah Vanderford, attending veterinarian for the Museum of Life and Science.

This is the third time in 24 years that wolves have been successfully bred at the museum, according to the release.

The pups will continue to receive preventative medical care every two weeks until they reach 16 weeks.

Adult red wolves typically weigh between 45-80 pounds and can live up to 15 years in captivity, but rarely longer than seven years in the wild, the press release said.

The red wolf is one of the planet’s most endangered species and is considered to be critically endangered.