Theodore H. “Ted” Reed, who transformed the National Zoo into an international destination, most notably through the acquisition of two Chinese giant pandas that sparked Washington’s love affair with the black-and-white bears, died July 2 at a nursing home in Milford, Del. He was 90.

The cause was complications from Alzheimer’s disease, said his son, Mark Reed, executive director of the Sedgwick County Zoo in Wichita.

Tall, bespectacled and with a full red beard, Dr. Reed was a 34-year-old veterinarian when he took over the modest-size National Zoo in 1956. At the time, he was among the nation’s youngest directors of an animal park, and during the next 27 years, he vastly broadened its scope and ambition.

I. Michael Heyman, who served as chief executive of the Smithsonian Institution and died in 2011, once described Dr. Reed as the director “who coaxed a sleepy part of the Institution to new life. . . . It was Reed who expanded the role of the zoo to vital research in veterinary science and the study of animal behavior.”

In an interview, Douglas G. Myers, the president and chief executive of San Diego Zoo Global, credited Dr. Reed with bringing science to the business of running the zoo and with helping to promote such novel concepts as conservation. “He was doing cutting-edge things before any of us ever thought of them,” Myers said.

Theodore H. Reed, shown with Asian elephants at the National Zoo in 1983, brought the pandas to Washington. (Fred Sweets/The Washington Post)

Dr. Reed created the zoo’s Scientific Research Department in the mid-1960s to study animal behavior, reproduction and breeding. In 1975, he oversaw the transfer of 3,000 acres in Front Royal, Va., to the Smithsonian to set up what is now the zoo’s Conservation Biology Institute, which conducts breeding research and programs for endangered and exotic species.

Dr. Reed was also responsible for the zoo’s acquisition of an Indian white tigress named Mohini in 1960 — the only ever exhibited in the country at the time — and a pair of Komodo dragons from the Indonesian government in 1964.

He successfully urged the creation in 1958 of Friends of the National Zoo, a membership-supported scientific and educational group. Heyman called FONZ “a bedrock of support” for the zoo, which does not charge admission. He also presided over the zoo’s renovation and construction projects, including a lion-tiger exhibit in 1976 and Beaver Valley in 1979.

For the public, the acquisition of giant pandas helped transform the zoo into a major draw for locals and out-of-towners. American zoos had long hosted the bamboo-munching endangered species — the Bronx Zoo in New York and Brookfield Zoo near Chicago had them in the 1930s.

The giant pandas Dr. Reed obtained for the National Zoo in 1972 — a male named Hsing-Hsing and a female named Ling-Ling — were reportedly the first in the United States in more than 20 years. Moreover, they had political clout. They were a goodwill gesture from communist China after then-President Richard M. Nixon’s landmark visit there to renew diplomatic ties. Nixon reportedly selected the National Zoo over at least four other big-city zoos because it was taxpayer funded.

In return for the pandas, Dr. Reed agreed to escort two musk oxen to Beijing from the San Francisco Zoo. The Washington Post reported that the oxen — destined for China despite their “unrevolutionary” names of Milton and Matilda — suffered from postnasal drip and a skin condition that was causing them to shed their hair.

Dr. Reed diagnosed “culture shock” from their hearing Chinese and recommended antibiotics and “tender loving care.”

Not all went as well as predicted back in Washington, either. One of the great hopes for the bears was their potential mating. But their courtship was troubled. “She was willing and he was anxious, but they just couldn’t coordinate their efforts,” Dr. Reed told Time magazine. They repeatedly failed to produce offspring that survived more than a few days. Ling-Ling died in 1992, and Hsing-Hsing died in 1999. (The zoo’s second pair of giant pandas produced in 2005 the zoo’s first surviving cub, Tai Shan.)

Dr. Reed recalled seeking advice from other zoo directors, who were less than helpful.

“I remember calling the zoo at San Francisco, where they had bred some red pandas,” he told The Post in 1983. “I asked them how they did it and they said: ‘Well, Ted, the first thing is you get a male and a female. Be sure about that because it won’t work otherwise. Then the next thing is you get real lucky.’

“I have come to the conclusion that unlike humans, most animals will not breed if they don’t like each other,” he added.

Theodore Harold Reed, whose father was an Army officer, was born July 25, 1922, at the Walter Reed Army hospital in Washington. He grew up all over the world, including the Philippines, but mostly in Norton, Kan.

He said that as a young man, he hoped to follow his father and brother into combat during World War II, but, because of color blindness, he instead was inducted in an Army program for veterinary students while attending Kansas State University. His father and brother were both killed in action, and he recalled he and his mother finding out by telegrams that arrived within three hours of each other.

He received a doctorate from Kansas State’s veterinary school in 1945 and spent much of his early career in Portland, Ore., at a local zoo and racetrack. When he arrived in 1955 at the National Zoo, he was one of three people on the technical staff. The next year, he succeeded director William M. Mann, who had led the zoological park since 1925.

One of Dr. Reed’s most traumatic experiences as director occurred after just two years on the job, when a 2-year-old girl was killed by an adult African lion after she slipped through a guardrail.

At the time, Dr. Reed defended the zoo’s safety record. But decades later, he called the animal park a “zoological slum” in need of costly upgrades. The philanthropic group FONZ was born in part because of the lion incident.

“It wasn’t until that little girl was killed that we got some construction,” Dr. Reed told The Post in 2003. “The zoo has always had a financial problem because we were a federal agency run by the Smithsonian Institution and paid for by the District of Columbia. I had to walk a tightrope between two organizations.”

Dr. Reed saw the budget climb to $10 million from $1 million by the time he retired. But more than the financial growth, the former veterinarian spoke piquantly about the animals in his care. He recalled every bite, kick and claw.

A bad chomp by a chimp named Jiggs left him with only partial use of two fingers on his right hand.

“I don’t blame the chimp,” Dr. Reed told The Post in 1972. “It was all my fault. You’re supposed to keep an eye on the animal closest to you. But I let my attention wander. I was looking at some other chimp, and Jiggs bit hell out of my hand. As I say, I don’t blame the chimp, but I’ll never forgive him for smacking his lips afterwards.”

Dr. Reed’s first wife, Mary Elizabeth Crandall, who helped raise some of the zoo’s animals, including tiger cubs, leopards and bear cubs, died in 1978. As he told The Post, they honeymooned at the Kansas City Zoo. “We had a good time, no matter what she says,” he quipped.

Survivors include his wife of 33 years, Sandra Foote of Milford; two children from his first marriage, Mark Reed of Wichita, and Maryalyce Jenkins of Wellington, New Zealand; three grandchildren; and one great-granddaughter.

“I guess you are specially fond of the animals you were closest to and worked with most; in my case, the white tiger and the pandas,” Dr. Reed said upon his retirement. “You never forget those animals, like your first girl.”

“Well, all I can say is I remember vividly my first meeting with the white tiger and with the white pandas, but actually I have no recollection at all of my first girl,” he added.