Resident White House canine Commander was back in the doghouse on Wednesday after the Biden family pet bit another Secret Service agent.
The feisty German shepherd, who arrived as a puppy in 2021, faces fresh training following what is reported to be at least the 11th such incident.
US President Joe Biden and his wife, Jill, have blamed the "stressful" conditions at the bustling residence for the dog's habit of nipping staff.
In the latest encounter an "officer came in contact with a first family pet and was bitten" on Monday evening, US Secret Service Communications chief Anthony Guglielmi said.
"The officer was treated by medical personnel on complex."
The Bidens have previously said they would get extra training for Commander after incidents including one that sent a victim to the hospital.
"As we've noted before, the White House can be a stressful environment for family pets," Elizabeth Alexander, communications director for First Lady Jill Biden, said in a statement to AFP.
"The first family continues to work on ways to help Commander handle the often unpredictable nature of the White House grounds."
She added that the Bidens were "incredibly grateful to the Secret Service and executive residence staff for all they do to keep them, their family, and the country safe."
Secret Service emails obtained through freedom of information requests by the conservative group Judicial Watch in July detailed 10 previous incidents at the White House and the Biden family home in Delaware, CNN reported.
The Bidens' other German shepherd, Major, also had trouble adapting to White House life after Biden was elected in 2020.
In 2021, he was briefly sent back to Delaware after at least one biting incident, and also underwent additional training. He was later dispatched to live with family friends.
Joe Biden attributed Major's unpresidential behavior to the way he gets surprised by Secret Service agents and others appearing around every corner in the busy White House complex.
The US presidential mansion has a long history as a pro-dog residence. More than 100 have roamed and sniffed its corridors.
The Bidens also have a cat - a short-haired tabby named Willow.