Overlong nails: a 2.4-fold higher risk of toe injury
Published by Planète Pets · managing editor: Clément Lacaille · how our guides are written
Nail trimming is usually filed under grooming, alongside brushing. A survey published in 2018 in the Journal of the American Veterinary Medical Association by Sellon, Martucci, Wenz, Marcellin-Little, Powers and Cullen turns it into an orthopaedic subject. Across 1,081 agility dogs — 207 with a digit injury, 874 controls — the multivariable analysis retains long nails as a risk factor, with an odds ratio of 2.4 (95% confidence interval 1.3 to 4.5) (see the study). Our grooming guides are gathered in the dog care and grooming section.
Contents · 5 sections
Why length changes the way the foot loads
A dog's toe is built to land pad first. A nail that protrudes touches down before it: the toe lifts slightly, the load shifts backwards, and part of the weight transfers onto smooth rigid keratin instead of an elastic pad. On a surface with grip, the nail catches and the toe twists. The geometry of the foot changes, not just its comfort.
The other factors recorded
The same survey quantifies three further associations. Missing front dewclaws multiply the risk by 1.9 (1.3 to 2.6) — the dewclaw helps stabilise the carpus through turns. A high weight-to-height ratio multiplies it by 1.5, and border collies come out at 2.3, which reflects both how they run and how heavily they are represented in the sport. Counterintuitively, risk falls with age (0.8): younger dogs get hurt more.
Surface matters, but not the way you would guess
A companion survey by Jimenez, Canapp and Percival, published in 2022 in Frontiers in Veterinary Science across 300 respondents covering 308 dogs, reports 35.7% of dogs injured in training against 11.2% in competition, with incidence varying by substrate: 3.8% on dirt, 7.5% on sand, around 10% on grass and artificial turf, 32% on rubber matting (see the study). Front digits accounted for 14.7% of training injuries.
What these figures do not prove
Both are retrospective self-reported surveys with no medical records reviewed. "Long nails" is never measured objectively, and the authors themselves urge caution: these are associations, not demonstrated causation. The 2022 sample was recruited through social media, and the rubber figure rests on a small denominator — none of the slip videos submitted involved that surface, in fact. Above all, none of this concerns pet dogs at home: you cannot transfer these percentages to the living-room floor. The loading mechanism does transfer, and it applies to any dog's foot.
- Odds ratio 2.4 for long nails, across 1,081 dogs.
- 1.9 for missing front dewclaws.
- 14.7% of training injuries involve the front digits.
- The practical test is one sentence long: on a hard floor, the nail should not click at a walk.
Trimming technique is covered in our guide to cutting nails at home; for dogs that refuse clippers, a grinder is often better tolerated. In large-breed puppies, the question of foot loading meets that of stable flooring during growth.
Frequently asked questions
How often should a dog's nails be trimmed?
The calendar matters less than the floor test: if the nail clicks on tiles at a walking pace, it is landing before the pad.
Should dewclaws be kept?
Agility data associate their absence with a higher rate of digit injury. This does not apply to loose hind dewclaws, which are a different matter.
My dog does not do agility — does this apply?
The percentages, no. The loading mechanism, yes: a nail bearing weight instead of the pad changes any dog's foot.
In our shop, for this use: Stainless steel nail clippers for small dogs and puppies (€17.90) · the whole shop
This guide is part of Planète Pets’s Dogs universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.