Cruciate Ligament Rupture
What is it?
The cranial cruciate ligament (similar to the ACL in people) stabilizes the knee. In dogs it usually weakens and degenerates over time before tearing partly or completely, often during ordinary activity. Many dogs eventually injure the other knee too.
What signs should I watch for?
Signs to watch for include sudden or gradual hind-leg limping, toe-touching or not bearing weight, sitting with one leg kicked out to the side, swelling or thickening of the knee, and stiffness after rest.
How is it diagnosed and treated?
Your veterinarian checks the knee for abnormal motion and takes X-rays; sedation may be needed. Surgery to stabilize the knee is often recommended, especially for active or larger dogs. Some small dogs are managed with rest, weight control, and rehabilitation.
Can it be prevented, and what's the outlook?
- Without stabilization, arthritis develops faster.
- With surgery and rehabilitation, most dogs return to good activity.
- Keeping a lean weight reduces risk.
Reviewed by the Adler Veterinary Hospital veterinary team, October 2026.
Dogs, especially active or larger dogs; often both knees
Who's at risk:
Hind-leg limping, toe-touching, sitting with a leg kicked out
Main signs:
Schedule a visit soon
Urgency:
When to call a vet right away
- Suddenly very lame on a back leg
- Not putting weight on the leg, or only touching the toes down
- Crying out when the knee gives way
- Difficulty getting up
Not sure whether it can wait? Call us anyway. Our team can help you decide.
Source:
Related conditions
Disc Disease (IVDD)
Hip Dysplasia
Bone Cancer