Éric Troncy
Credit: GREPAQ
Many people think declawing their cat is just minor surgery-a practical way to protect furniture and to prevent getting scratched. But it's actually amputation, a removal of the last phalanx bone of a cat's toes, a procedure called onychectomy.
"They aren't just cutting off the claws; they're mutilating the animal," said Dr. Éric Troncy, an Université de Montréal veterinary medicine professor who heads the Groupe de recherche en pharmacologie animale du Québec (GREPAQ).
Declawing has been banned in Quebec since 2024 but is legal in several provinces and most U.S. states. The American Veterinary Medical Association (AVMA) has stopped short of condemning it outright, citing a lack of solid scientific data.
"This surgery is still performed on about a quarter of North American cats," Troncy said. "Until recently, the AVMA relied on just three anecdotal reports and had no serious scientific evidence of the pain caused by this practice."
Distinguishing the chronic pain caused by declawing from other sources of pain such as osteoarthritis, which affects the overwhelming majority of older cats, is complex.
But in a new study, GREPAQ researchers were able to isolate the consequences of declawing based on objective clinical measurements. To do so, they looked at a unique cohort of cats with osteoarthritis, a quarter of which had been declawed.
The scientists' conclusion is clear: far from just being painful during the procedure, declawing causes chronic pain, hypersensitivity, irreversible nerve damage and mobility issues, particularly in heavier cats.
Nearly 200 cats studied
UdeM veterinary students Mathieu LaChance, Colombe Otis, Aliénor Delsart and Beatriz P. Monteiro, along with statistician Tristan Juette, played key roles in the study's research team.
They analyzed data from eight previous studies, conducted between 2010 and 2023, covering 188 cats divided into three groups: healthy, non-declawed cats; non-declawed cats with osteoarthritis; and declawed cats with osteoarthritis.
All the animals were selected after a full assessment to rule out other pathologies and ensure the comparability of results.
Each cat underwent a series of non-invasive tests: an assessment of their mechanical pain threshold, observation of tolerance to repeated stimulation, an objective gait analysis, and electrophysiological measurements of nerve function.
Measuring neuropathic pain
To quantify neuropathic pain, the veterinarians used a von Frey esthesiometer.
"We press a filament connected to a sensor against the underside of the paw and measure the pressure at which the cat pulls away," Troncy explained. The results were striking:
- Healthy cats withdrew their paws at an average of 166 grams of pressure.
- Non-declawed cats with osteoarthritis withdrew at 130 grams.
- Declawed cats with osteoarthritis withdrew at just 101 grams.
Declawed cats therefore tolerated much less pressure, a clear sign of heightened sensitivity and chronic pain.
Increased sensitivity to pain
Another test confirmed this hypersensitivity to pain.
In humans, "our bodies are constantly exposed to stimuli of all kinds-light, smells, drafts," Troncy noted. "Normally, the spinal cord acts as a filter, preventing those signals from overwhelming the brain.
"However, when this filtering is disrupted, the stimuli pile up, overloading the spinal cord and amplifying the messages sent to the brain. The brain then tries to inhibit them, but the constant effort exhausts people suffering from chronic pain.
"The same thing happens in cats."
To measure this, the research team designed a small cuff that fit around each cat's paw or tail. It was connected to a mechanical device and delivered brief stimuli, comparable to small puffs of air, to the cat's skin.
In healthy cats, the repeated stimuli elicited little reaction. But the tolerance was much lower in cats with osteoarthritis, and even lower in declawed cats with osteoarthritis.
"Their nervous system has no reserves, no buffer," Troncy said. "You can see it irritates them, they try to pull off the cuff. At that point, we'd stop the test immediately."
The healthy cats tolerated an average of 30 stimulations without reacting, but the threshold decreased in cats with osteoarthritis and went down to 10 to 15 stimulations in declawed cats with osteoarthritis, a clear sign of neuropathic pain.
Instead of filtering signals, their nervous system amplified them.
"This response shows that their entire nervous system is overloaded, making daily life uncomfortable."
Struggling more with their weight
Gait analysis revealed that declawed cats struggle more to support their body weight on their paws. The heavier the cat, the greater the difficulty. "The force exerted at ground level depends on weight," Troncy explained.
It's more obvious in dogs - "a Chihuahua never needs the same support as a Great Dane," Troncy said - but "it's the same with cats: their weight can range from 1.5 to 10 kilograms, which makes a huge difference.
"When comparing force responses according to body size, we found that in lighter cats with osteoarthritis, the declawed and non-declawed cats had similar results," he said.
"However, as weight increased, the impact of declawing became more significant." Heavier declawed cats had much more difficulty placing their paws properly and maintaining a natural gait, Troncy added.
Irreversible nerve damage
Electrophysiological tests carried out by Dr. Aude Castel, an UdeM veterinary neurologist, also revealed that nerve conduction was significantly impaired in declawed cats - a sign of axonopathy, or degeneration of nerve fibres.
"She measured nerve activity by placing electrodes along the nerves," Troncy explained.
"Cats with osteoarthritis showed some impairment, but it was much more pronounced in cats that were also declawed. This proves that the nerve itself is damaged. The axon - its core - is no longer healthy."
Troncy believes the verdict is clear: "We now have solid scientific evidence that declawing causes chronic pain and irreversible nerve damage."
Unlike amputations performed to save a sick or injured animal, onychectomy offers no medical benefit, he concluded. "It's surgery of convenience that permanently reduces a cat's quality of life and is ethically unacceptable."
About this study
"Declawing in cat is associated with neuroplastic sensitization and long-term painful afflictions," by Éric Troncy et al., was published Aug. 17, 2025 in Scientific Reports.
