McDonald spoke to a few hundred people at the American Veterans national convention. He is scheduled to visit the city's VA hospital on Thursday.
The VA has been shaken by reports that some veterans died while waiting for treatment. Some workers have been accused of covering up scheduling problems. The scandal led to the resignation of former VA Secretary Eric Shinseki and last month's appointment of McDonald, a former West Point graduate, Army Ranger and Procter and Gamble CEO.
In the past two months, the VA has made more than 838,000 referrals for veterans to receive care from private doctors, McDonald told the AMVETS. That's an increase of 166,000 referrals, or about 25 percent, from the same period last year.
The statement drew applause from veterans in attendance.
"Until we get systems up to capacity, we're expanding our use of private care and other non-VA health care to improve access for veterans experiencing excessive wait times," McDonald said. "And we're monitoring non-VA care to ensure veterans receive the best that they deserve."
He said each referral results in seven medical visits or appointments, on average.
McDonald also addressed hiring practices at VA hospitals, calling them laborious, complicated and time consuming. He said about 1,000 new doctors, nurses and clerks were needed at the Phoenix VA hospital. Another 500 new doctors, nurses and clerks were needed at the VA facility in North Las Vegas.
"I'm going to be out there recruiting these people, and I would like your help," he said. "If you have any names, please send them to me."
A $16.3 billion VA overhaul law signed by President Barack Obama last week devotes $10 billion to pay private doctors to treat qualifying veterans who can't get prompt appointments at the VA's nearly 1,000 hospital and outpatient clinics. The law also includes $5 billion to hire more doctors and other medical and mental health professionals.
The VA spent about $4.8 billion last year on medical care at non-VA hospitals and clinics - about 10 percent of health care costs for the Veterans Health Administration, the agency's health care arm.
McDonald also said the VA is updating its "antiquated" appointment scheduling system. Clinics are operating longer hours, and the agency is using temporary staffers to get care to veterans faster, he said.
McDonald's appearance at the AMVETS convention was part of a tour that has included stops at the Phoenix VA hospital where the scandal erupted and a disabled veterans' convention in Las Vegas in the past week.
He was scheduled to meet Thursday with employees and managers at the VA's Memphis medical complex, which has experienced its share of problems.
A VA inspector general's report released in October said three patients had received substandard care in the hospital's emergency room and died. The hospital says it has fixed the problems that led to the deaths.
Local veterans also have complained of long wait times.