A senior capybara at the Santa Barbara Zoo was euthanized Friday after specialist veterinarians found an “inoperable” mass in her throat that made it difficult for her to eat or breathe, a zoo spokesperson said.

The zoo’s animal care team first noticed that Poppy, 8, was breathing irregularly, prompting exams and diagnostic scans. She later was given an endoscopic exam to further explore the mass and whether treatment was possible.

The mass, however, which was severely obstructing her airway, could not be surgically removed, according to Julie Barnes, vice president of animal care and health at the zoo.

“Knowing there was no treatment that could give Poppy a meaningful chance of recovery, we made the heartbreaking decision to humanely euthanize her rather than allow her to suffer,” Barnes said.

Poppy had just celebrated a birthday on Aug. 5. She was born at the Greater Vancouver Zoo in 2018 and was hand-raised as a pup, according to the Santa Barbara Zoo.

Poppy was considered geriatric by Santa Barbara Zoo officials. Capybaras typically live up to seven years in the wild.

The zoo’s other capybara, a 4-year-old named Antonio, is also facing health problems following a rare blood cancer diagnosis.

Antonio has begun chemotherapy for multiple myeloma, which originates in the plasma cells of the bone marrow, according to zoo officials.

He has received specialized care and testing for the past two months, off-habitat, after the animal care team noticed “he was not feeling well” and was experiencing nosebleeds.

“We have already seen some improvement since starting treatment with corticosteroids, and our team is closely monitoring his response, comfort and quality of life,” officials added.

Antonio was born on July 26, 2022, at the Montgomery Zoo in Alabama, and he is described as having a big personality and “even bigger appetite.”

Antonio’s diagnosis is historic. It is the first known case of successfully diagnosing multiple myeloma in a living capybara at an Association of Zoos & Aquariums-accredited institution, according to zoo officials.

“His prognosis remains guarded, but our veterinary and animal care teams are doing everything possible to give him the best care and chance for a meaningful recovery,” officials said.

Poppy’s death follows the recent death of three of the zoo’s red pandas: two cubs and their mother, Ruby. 

The cubs, born to Ruby and Raj, died in July.

The first was found dead in its nest box during a routine check. 

The second cub was transferred to an incubator to receive special care because it was not nursing properly, but it died a week after its sibling despite intensive care and around-the-clock care, according to spokeswoman Andrea Gruber.

A necropsy showed a “significant amount of pericardial effusion (fluid surrounding the heart) and some congestion of the lungs” in the second cub, Gruber said last month.

Red panda cubs have an infant mortality rate as high as 40% in their first year of life, according to zoo staff.

Ruby died earlier this month of suspected Addison’s disease, which affects the body’s ability to produce cortisol and other essential hormones.

“It’s been a difficult few weeks for us here at the zoo,” spokespeople posted on social media.

Community members flocked to the comment section to mourn Poppy, send get-well wishes to Antonio and send words of support to zoo staff. 

Josh Feinblatt, a self-described “big capybara fan,” wrote that meeting Poppy at the Santa Barbara Zoo left a lasting impact on him. 

“I cried before and after the encounter. Poppy spent the entire time, and some extra, with us as we got to feed, scratch, and talk to & learn about her. It changed my life, and my phone background has been a picture of Poppy ever since,” he wrote on social media.