A goofy, golden-brown labradoodle with a curly mop, Hudson resembled nothing so much as a “giant teddy bear,” his owner Ashley Burden recalls. He was the ring bearer at her wedding, an enthusiastic camping buddy and part of her family for 12 years.
When he died, Hudson had recently received his monthly injection of a relatively new arthritis drug, Librela. At first, the shots helped with stiffness in his joints, and Hudson – an otherwise healthy dog – was running and jumping again. But soon after his third dose last January, Ms. Burden noticed unusual activity. Hudson was panting and urinating frequently. He stopped wanting to play, and stared into space.
A couple of weeks later, Hudson became very lethargic and began vomiting. An emergency vet sent him home after inconclusive tests. By the next day, the dog’s heart was pounding, he could not stand and he struggled even to lift his head. Ms. Burden raced him back to the veterinary hospital. Shortly after they arrived, Hudson died.
“It’s hard enough to lose a dog,” Ms. Burden says. “To watch it happen this way, it just makes you feel really guilty.”
Ms. Burden is one of several dog owners who are reporting serious alleged side effects after their pets received Librela, and questioning whether the drug is to blame. Pet owners and veterinarians have reported adverse reactions to health agencies in Canada and internationally. According to a class-action lawsuit filed last month by a pet owner in New Jersey, “Librela has been associated with thousands of reported adverse events in dogs,” including lethargy, incontinence, an inability to walk and, for some, death. For this story, The Globe and Mail spoke with eight people whose pet’s health declined.
They say they were assured that Librela had no side effects aside from minor swelling at the injection site, and want to know why they were not given a fuller picture of the risks so that they could have made an informed decision.
Librela and a similar drug for use in cats, Solensia, both made by U.S. manufacturer Zoetis Inc., were the first two “monoclonal antibody” products to be authorized as veterinary drugs in Canada, in 2021, and began being prescribed here last year. Zoetis has responded to owners’ concerns by saying the drug has been rigorously tested and is safe.
The promise of such medications is a new way to manage pain, particularly in aging pets. This is a big business in veterinary medicine, as people are willing to spend more not just to extend the years they have with their animals, but also to provide comfort and quality of life. Zoetis executives have said osteoarthritis drugs will be the company’s “next $1-billion franchise.”
For companies that promise new veterinary care options, the opportunity is significant: The global animal health market was worth US$39.9-billion in 2021, according to NDP Analytics. Sales of animal drugs are growing, partly due to advancements in medicines, as well as the boom in pet ownership during the COVID-19 pandemic.
Traditionally, a common prescription for pain has been non-steroidal anti-inflammatories (NSAIDs). But older pets “may be sensitive to the effects of NSAIDs on the kidney, liver and gastrointestinal system,” Health Canada noted in a report in 2021, the year the agency approved Librela.
Zoetis has marketed these drugs as a new solution. Monoclonal antibodies are designed to bind to a protein in the patient’s body called a nerve growth factor, which sends pain signals to the brain, and disrupts those signals to relieve pain. Librela is administered with a monthly injection.
But some dog owners have reported a troubling and sudden deterioration in the health of their pet.
Before his two injections of Librela, Johnny was a “big healthy dog,” said his owner Roberta Mercier. At 13, he had stiffness in one hind leg. After his second shot, this past May, things changed quickly.
The same night, Johnny began panting heavily. When he tried to stand, his legs would splay outward and he fell. Over the following days, he appeared disoriented and no longer lifted his head when Ms. Mercier came into the room.
Her veterinarian did not communicate any risks when suggesting the prescription, Ms. Mercier said. She feels intense regret that she did not do more research.
“I feel sick about this, because I spent my whole career giving medication safely and teaching people how to give medication safely,” said Ms. Mercier, a retired registered nurse in Langley, B.C.
Ms. Mercier was preparing to put Johnny down when his breeder told her about a Facebook group for pet owners discussing experiences with Librela. There, she read about some animals who gradually improved after stopping the injections. It convinced her to wait. Johnny is doing better, but Ms. Mercier is still troubled by how close she came to euthanizing him.
Facebook has not traditionally been known as a reliable information source. But for pet owners hoping to research such medications, other avenues can be hard to find.
Health Canada maintains a database of reported side effects related to drugs for human use. But while the agency also oversees veterinary drugs, and receives reports about adverse reactions to those medications, the information is not easily accessible to the public.
Data are provided upon request directly to Health Canada’s Veterinary Drugs Directorate – something many pet owners are unlikely to know.
The Globe asked Health Canada for a summary of adverse reaction reports submitted for Librela. The summary indicated that in the first half of 2024, the agency had received 187 such reports; there were 263 in 2023.
But it can be difficult to know what to make of that data: Each report can involve one or more products. Health Canada specifies that the reports “should not be used as a basis for determining the incidence of a reaction or estimating risk for a particular product,” since the total number of adverse reactions and the number of patients exposed to a drug are both unknown.
The same applies to information gathered by the European Medicines Agency, which requires drug companies to report on “adverse events” related to veterinary drugs, even if they occur outside of Europe, including in Canada. The European database comes with the disclaimer that the information does not confirm a link between the medicine and the reported side effects.
In 2023, the agency’s database included 840 such reports related to Librela in Canada, made by veterinarians, owners and others. Of those, 225 were classified as “serious.” (The numbers differ from Health Canada’s, which could be because the latter requires companies to submit reports only about serious cases, while Europe requires all reactions to be submitted, according to Health Canada. The agency also said this could be explained by reports involving more than one drug, submitted by other drug manufacturers besides Librela’s.) So far this year, as of late October, the European database has recorded 970 cases in Canada, 325 of them classified as serious.
Many of the dogs in the European reports were taking other drugs in addition to Librela, but there are cases in which Librela is the only drug listed. Those include a case of a dachshund who developed a fever, lethargy and was unable to stand up; a hound who exhibited “confusion” and abnormal breathing; and a German shepherd who was found dead after showing symptoms such as panting and a seizure.
Whether such health outcomes are caused by Librela is unproven. According to the company, none of the reported clinical signs have been classified as “more than rare” under European Medicines Agency categorization, meaning they have been reported in between one to 10 animals per 10,000 treated. Zoetis declined to provide the number of total adverse reaction reports it has received related to Librela.
“We remain confident in the safety and effectiveness of Librela for controlling osteoarthritis pain in dogs, when used according to the label,” Zoetis spokesperson Jennifer Albano wrote in a statement to The Globe.
But Dann Soucy, a former teacher in Montreal, says that even if the side effects were rare, she wishes she had been provided that information before agreeing to Librela injections for her golden retriever, Abeylle.
“I did not get to make an informed decision. That is so vital,” said Ms. Soucy. The day after the first shot, in March of 2023, the dog’s hind legs gave out. Abeylle seemed confused, stared into space, ran into walls and didn’t react when Ms. Soucy called her name. She was panting heavily, vomiting and urinating on herself. Ms. Soucy reported the symptoms to her veterinarian, who told her they were unrelated to Librela.
“It was all old age,” she said, recalling the conversation. Abeylle was nine years old at the time of the injection. “But a dog doesn’t get seven or eight or 10 problems within a couple of weeks.”
Ms. Soucy has paid for canine physiotherapy, osteopathy and laser treatments. Living on a fixed income, she has stopped taking her own medications at times in order to afford the treatments. Abeylle can now walk, but only short distances.
Zoetis often talks about the “human-animal bond” that fuels its business: An investor presentation this year noted that “Gen Z and Millennials are fuelling the humanization of pets,” and also described research that found 86 per cent of pet owners “would pay whatever it takes if their pet needed extensive veterinary care.”
During a September appearance at the annual Morgan Stanley Global Healthcare Conference, Zoetis chief executive officer Kristin Peck said Librela has seen the fastest growth in “clinic penetration” of any product in its history, with reach in more than 80 per cent of U.S. veterinary clinics and strong reorder rates.
In its most recent quarter, sales of Librela in the U.S. were US$55-million. International sales of Librela accounted for another US$62-million. In total, global sales of the drug grew by 123 per cent. According to the company, more than 18 million doses have been distributed worldwide.
For Lynne Cutting, Librela has been worthwhile. Her golden lab, Lunar, has been receiving shots every four to six weeks, at $100 per treatment, for more than a year.
“Within three days, she was a different dog,” she said, recalling the first injection. Lunar has elbow dysplasia, and had been increasingly showing signs of pain; now she moves more comfortably and seems happier, Ms. Cutting said. She would “cautiously recommend” the drug to others, she added, with the caveat that owners should be informed of the negative experiences some have reported.
Liza Dawber of Stavely, Alta., wishes that she had known about those cases. In December of 2023, Ms. Dawber’s veterinarian diagnosed her Rhodesian ridgeback, Rocco, with mild osteoarthritis, and recommended Librela. Like many 10-year-old dogs, he’d begun to slow down – he needed a small running start to jump into her SUV – but was otherwise “perfectly healthy,” she said.
“Within 24 hours, we went from a dog that could jump … to a dog that couldn’t control his back legs or his bowels,” Ms. Dawber said. He was panting, drooling and stumbling. In one instance, Rocco began defecating while walking across her living room, and when he realized what was happening, he tried to run outside. His legs gave out and he fell in his own feces.
“That is hard to see,” Ms. Dawber said.
Still, Ms. Dawber did not suspect the drug at first, since it had been promoted as having very few side effects.
Other owners heard similar messages.
Kim Campbell of Nanaimo, B.C., said staff at her veterinarian’s office told her Librela was a “miracle drug” with no side effects beyond some localized soreness and swelling around the injection site. Her bichon frise, Frack, lost all control of her hind legs after the second Librela shot.
“My concern is, every client should be informed about the possibility of this happening,” Ms. Campbell said. After she halted the shots, it took four months for Frack to walk again on her own.
The lawsuit filed in New Jersey states that Zoetis’s advertising and promotional materials represented Librela as safe, “without disclosing many significant adverse effects associated with the product.” It also states that the company “has downplayed safety issues” related to the drug. The allegations have not been tested in court.
Zoetis is aware of the lawsuit, Ms. Albano wrote, and added that the drug was approved through “extremely robust and rigorous processes of global agencies” including Health Canada.
Once a drug is on the market, Health Canada’s Veterinary Drugs Directorate “conducts post-market surveillance and reviews reported adverse reactions to determine whether there is a safety issue that requires action,” Health Canada spokesperson Joshua Coke wrote in an e-mail.
Since Librela was approved in Canada in 2021, Health Canada has twice asked Zoetis to update the product label to reflect adverse reactions reported by the public. The first occurred before the drug began to be sold here, based on updates in Europe where it was already in use. The second was in July of this year: Zoetis was asked to include an amended list of reported reactions, “due to an increase in frequency of their occurrence as compared to when previously reviewed,” Mr. Coke wrote.
Zoetis was also asked in July to provide a new “client information sheet” listing potential side effects including decreased appetite, lethargy, balance problems or unco-ordination, drinking more, urinating more or urinary incontinence, diarrhea and vomiting. Because Librela is administered by veterinarians, the new sheet “was considered an appropriate way to provide information to animal owners who may not have access to product packaging,” Mr. Coke wrote. However, he added that while vets “could” provide the sheet to owners, to better inform them about the drug, Health Canada cannot require vets to do so because veterinary medicine is provincially regulated.
The Globe contacted provincial veterinary regulators in four of Canada’s largest provinces to ask whether they have communicated with veterinary professionals to either recommend or to require that this new information be provided to owners before administering Librela. Representatives for the College of Veterinarians of Ontario and The Alberta Veterinary Medical Association replied that veterinarians are expected to share information about common side effects and serious risks before administering a drug, but they did not confirm any such communication regarding Librela. The College of Veterinarians of BC did not respond by the time of publication.
“According to the rules governing the practice of veterinary medicine in Quebec, veterinarians are under no absolute obligation to provide their clients with the Librela side-effects sheet for dog owners receiving this medication,” Véronique Robert, a spokesperson for l’Ordre des médecins vétérinaires du Québec, wrote in an e-mailed statement. However, she added that vets have a duty to inform clients of the nature of medications they prescribe, including any possible “dangers that its use may entail.”
Zoetis’s own research has found that 78 per cent of U.S. veterinarians are very satisfied with the drug, and that 65 per cent worldwide will treat more dogs because Librela is an option.
And the company is encouraging vets to prescribe Librela more often, for moderate cases. This fall, the company’s “field force” is planning to visit vet clinics with that message, Ms. Peck said at the Morgan Stanley conference in September.
Edward Bassingthwaighte, a veterinarian in Taradale, Australia, believes Librela should only be used as a last resort.
“There is no way in the world that I believe that Librela should ever be a first treatment for arthritis,” he said.
Dr. Bassingthwaighte has not prescribed the drug, citing concerns about the adverse reaction reports that pet owners around the world are sharing. He has also heard from other veterinarians who have observed animals’ physical mobility deteriorating after taking the drug.
“You get quite a large number of animals that will be okay with it, but you’ve got obviously a pretty heavy, sensitive tail of the bell curve that are not coping with it,” said Dr. Bassingthwaighte. “…I basically want people to understand that these drugs are not without risk. And I think the risk is being minimized.”
Ms. Dawber, for one, wishes she had known about possible side effects. In the months following Rocco’s Librela injections, she spent more than $4,000 on veterinary visits, massage therapy, osteopathy and rehabilitation treatments. Rocco’s symptoms did not improve.
“It’s been pretty horrific. It’s been lots of tears, lots of sleepless nights,” Ms. Dawber said. In July, she took him to the veterinarian for the last time. As Rocco was weighed before being euthanized, Ms. Dawber noticed that a rubber mat covering the scale had something printed on it.
It was an advertisement for Librela.