OAKLAND (CBS SF) — There were heavy hearts at the Oakland Zoo Tuesday after veterinarians were forced to euthanize tiger sisters Molly and Milou, who had been among the favorites of visitors for the last decade.

Zoo officials said the tigers had been struggling with severely declining health in their old age including advanced kidney disease and debilitating arthritis.

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Tiger sisters Molly and Milou (Oakland Zoo)

“Together, our animal care and veterinary staff made the extremely difficult decision to end their suffering and euthanize both tigers this morning,” zoo officials said.

“They were loved and we will miss them deeply,” officials continued. “They will always hold a special place in all of our hearts.”

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Ginger, the tigers’ sister, was euthanize in August after a long battle with chronic kidney disease.

The 16-year-old big cats came the zoo as rescues from private owners in Texas where they were used in a traveling animal show. Visitors could pay $20 to have pictures taken with them.

Tiger sisters Molly and Milou (Oakland Zoo)

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The Texas couple had raised the animals from birth. When the couple divorced, the tigers moved to the Gladys Porter Zoo in Brownsville, Texas. But because that zoo was at its maximum tiger capacity of 10, the Oakland Zoo stepped in and gave them a home.