Gov. Jerry Brown's dog Sutter has fallen critically ill, a spokesperson for Brown's press office confirmed.

The 13-year-old Pembroke Welsh corgi suddenly fell ill on Friday and was rushed to a Sacramento-area animal hospital. Numerous masses -- most likely cancer, according to the press office -- were discovered in Sutter's intestines, lymph nodes and liver.

First Dog Sutter Brown is a fixture both at the Capitol, where he's often spotted being walked by staffers, and on Twitter where he and his corgi sister Colusa are very active.

He was adopted by the governor and First Lady Anne Gust Brown shortly after the 2010 gubernatorial election. Before becoming the first dog, Sutter was owned by Gov. Brown's sister, Kathleen Brown.

Sutter has been uncharacteristically quiet on Twitter recently. His last tweet was more than a month ago, on the final day of session:

The press office said Sutter pulled through surgery, but his veterinarians were not able to remove all of the cancer. His condition remains critical.

Biopsies revealed on Friday that he has a very aggressive form of cancer. A spokesperson for Brown said Sutter's treatment options are limited.

"We're still hopeful he can get home to spend what limited time he has left with his family," a spokesperson for Brown said.

Sutter will continue to rest and recover at the animal hospital. "The focus is on getting him well enough to come home, so he can spend time with his family, including Colusa, whose spirits have been very low with her brother gone."