Updated September 25, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: The dog equivalent of an ACL is the cranial cruciate ligament (CCL), and tearing it is one of the most common causes of back-leg lameness. Unlike in people, CCL tears in dogs usually result from gradual ligament degeneration, then a final tear. Surgery, most commonly TPLO, is usually recommended for medium and large dogs, while some small dogs do well with conservative care. Many dogs later tear the other knee, so weight control matters.
Signs
- Sudden or gradual back-leg lameness
- Toe-touching or holding up the leg
- Sitting with the leg stuck out to the side
- Swelling on the inside of the knee
- Stiffness after rest
- A clicking sound if the meniscus is torn
Diagnosis
- Exam for knee instability (drawer test and tibial thrust)
- X-rays, often under sedation
Treatment options
- TPLO (tibial plateau leveling osteotomy): changes the knee angle so the ligament isn’t needed
- TTA and other bone-cutting procedures
- Lateral suture: often used in smaller dogs
- Conservative care: weight loss, pain relief, bracing, and rehab. Better suited to small dogs
Recovery
- Strict leash-only activity for about 8–12 weeks
- Rehab exercises
- Pain medication as prescribed
- Recheck X-rays
More: TPLO recovery and arthritis treatment.
Sources
- Merck Veterinary Manual: Cranial cruciate ligament disease in dogs
- American College of Veterinary Surgeons (ACVS): Cranial cruciate ligament disease
- Comerford EJ, Smith K, Hayashi K. Update on the aetiopathogenesis of canine cranial cruciate ligament disease. Vet Comp Orthop Traumatol. 2011
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.