The group issued a statement on its Facebook page, explaining the incident and sending prayers to the victim.
The dog bite is under investigation.
It occurred just after 6 p.m. at the Center Township facility, officials said, when the man came to the shelter to re-adopt a Shar-Pei mix which he had given up in late November because of “hard times.”
The attack occurred outside the shelter as the man was leaving with the seven-year-old dog.
“While in our care, staff and volunteers had no behavior issues or incidents with the dog,” the statement said.
“We are taking this incident very seriously and working to investigate what happened to prevent a similar occurrence in the future.”