The silence in their home is heartbreaking.
The Mignosa family has gone four months without their lab, Cooper—four months without him greeting them at the door when they return home.
“He was just the best. He was just part of our family,” Lisa Mignosa said. “It’s very devastating.”
It’s been four months since the family has seen Cooper splash in the ocean and trot through the neighborhood.
“Everyone in the town would know him. We’d walk him and they’d know him more than they knew me. They’d be like ‘Cooper’, ‘Cooper,’” Sydney Mignosa remembered.
Cooper’s walks were cut short in December. The devastated family said the medicine meant to help Cooper; killed him.
7 Investigates found thousands of other families reported their pets were also harmed by the same drug.
Cooper was 9-years-old when the Mignosas noticed he was having a difficult time getting down the stairs.
“We were figuring out how to help him,” Lisa Mignosa said.
Their vet recommended Librela, a monthly injection used to treat joint pain in dogs.
The first shot went well, but after the second dose, things took a turn.
“He wouldn’t eat. He was like a deer in the headlights, just like in a fog. He wouldn’t sleep, he was panting,” Lisa Mignosa described.
“It was very heartbreaking to see him in that state,” Sydney Mignosa remembered. “He didn’t have control over his body.”
The family said their veterinarian diagnosed Cooper with Immune-mediated hemolytic anemia (IHMA).
The severe autoimmune disease caused Cooper’s body to attack his red blood cells.
The Mignosas are convinced Librela caused the illness. “We just laid with him and cried,” Lisa Mignosa said.
The family was forced to make the difficult decision to put Cooper down shortly after he received his second dose of Librela.
The Mignosas and their vet filed a report with the drug maker, Zoetis. “I was really mad and really upset about it all. I just wanted to be heard and hope to make a difference,” Lisa Mignosa said.
Less than a week after Cooper’s death, the U.S. Food and Drug Administration (FDA) sent a message to vets about potentially dangerous side effects from Librela.
7 Investigates found that the agency had received more than 10,000 reports of adverse reactions since the drug was approved in 2023.
Some of those reports included the same disease Cooper was diagnosed with. Of all the reports, around 900 dogs reportedly had to be put down, according to FDA data.
“If we would have known the correct side effects prior we would have never done it but we weren’t notified nor was any vet at that point,” Lisa Mignosa said.
The Mignosas aren’t the only ones who felt misinformed. A class action lawsuit filed in October alleges Zoetis “failed to adequately inform consumers and prescribing veterinarians about the dangers of Librela.”
The lawsuit also claims the company “misled consumers” by “failing to disclose known potential adverse events.”
In a statement to 7 Investigates, a spokesperson for Zoetis said veterinarians have administered 25 million doses of Librela globally and the company remains “confident in Librela’s safety and effectiveness.”
Zoetis also stated it is “deeply committed to listening to – and working with – veterinarians and pet owners, and we take very seriously our obligation to gather as much relevant information as possible when potential adverse events are reported to us.”
Zoetis updated Librela’s label in February. The change included listing some of the adverse events reported to the FDA.
A FDA spokesperson told 7 Investigates the agency is “currently reviewing and assessing adverse event reports in dogs who received Librela and will provide further information when available.”
The medication is still approved and being used, including by veterinarians at Angell Animal Medical Center.
“We have it. We use it. We have patients that are doing well on it. We try to take a pretty conservative approach with it. It’s not just for pain relief,” explained veterinarian Dr. Susan O’Bell. “I think it is one more tool we have. It’s definitely not the first thing that most of our primary care vets or orthopedic people are reaching for.”
Dr. O’Bell said the hospital has only seen minor side effects from Librela but pet owners should be aware of the risks before opting to use the drug.
“I think it’s a conversation with your veterinarian about. Are there risk factors that might make it not the best choice for your pet?” she said.
As for the Mignosas, they hope their choice to share their story helps save other dogs.
“People like us who have lived this are the ones making the noise and causing some change,” Lisa Mignosa said.
“We miss him so much and it’s just not the same without him.” Sydney Mignosa said.
(Copyright (c) 2026 Sunbeam Television. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)