PORTLAND — An Oregon Health & Science University laboratory was cited for violating animal welfare laws after five prairie voles died of thirst, federal inspectors said.

The U.S. Department of Agriculture also cited the university after a person risked contaminating surgical tools while probing a ferret's brain with an electrode in January as part of research into how the animals hear, the Oregonian/OregonLive reported.

The violations come after department officials performed a routine inspection of the university's animal research facilities in Portland last month.

“We really do take our responsibility to care for our animals very seriously,” said Kim Saunders, the top university veterinarian for research animals. She added the findings in January do not indicate a pattern of animal mistreatment.

Ferret research was shut down for a month last year after inspectors identified three violations, and the vole lab sparked concerns after testing how alcohol affects the animals, inspectors said.

Two anti-animal research groups, People for the Ethical Treatment of Animals and Stop Animal Exploitation Now, have urged the federal government to put an end to the university's work.

“How hard is it to remember to put water bottles in animals’ cages?” said Kathy Guillermo, senior vice president for PETA.

The animals should be confiscated, Stop Animal Exploitation Now Director Michael Budkie said in a complaint Tuesday to the federal agency.

“Otherwise, the next time that your inspector returns, there will most certainly be fewer living ferrets at OHSU,” Budkie said. “And if more ferrets die due to OHSU negligence, their blood will be on your hands.”

According to federal records dating back to 2014, the agency's findings bring the number of serious violations at the university's animal labs to nine.