Reviewed by: Dr. David Allman, DVM, DACVS-SA | Surgical Director, VROC
If your dog suddenly starts limping on a back leg, it is reasonable to be concerned. Cruciate ligament injuries are among the most common orthopedic problems veterinary surgeons treat in dogs and cats. Early evaluation can make a meaningful difference for comfort, joint health, and long-term mobility.
At a glance:The most common dog torn ACL symptoms include sudden limping on a back leg, toe-touching, stiffness after rest, trouble rising or jumping, swelling around the knee, a popping or clicking sound, and sitting with the injured leg kicked out to the side. These signs do not confirm the diagnosis, but they are a strong reason to schedule an orthopedic evaluation.
One important thing to understand up front:a torn cruciate ligament usually does not heal back into a normal stable ligament on its own. Some dogs (NOT doodles, Huskies, Spaniels, or the like), can compensate with scar tissue and careful management, but underlying knee instability often remains, especially in larger or active dogs.
What is a torn ACL, or CCL, in dogs?
Pet owners often use the term “dog ACL tear.” In dogs, however, the ligament involved is the cranial cruciate ligament, or CCL/CrCL, which is similar to the ACL in people.
The cranial cruciate ligament is one of the main stabilizers inside the knee, which veterinarians call the stifle joint. It helps prevent the lower leg bone, the tibia, from sliding forward abnormally when your dog moves. When that ligament stretches, partially tears, or fully ruptures the knee becomes unstable. That instability is painful, and over time will contribute to arthritis in the joint.
Unlike many human ACL tears that happen during a single random dramatic injury, canine cruciate disease often develops gradually. Factors such as ligament degeneration, genetics, body weight, size, activity level, and breed can all play a role. That is why a dog can tear a cruciate ligament doing something as ordinary as jumping off the couch, turning quickly in the yard, or getting up after rest.
Taking a closer look at dog torn ACL symptoms
Most owners notice something is off with how their dog moves before they know what it means. Signs of a torn ACL in a dog may include:
Sudden hind-leg lameness.A limp on a back leg that appears quickly is one of the most common first signs.
Toe-touching or holding the leg up.Your dog may rest only the toes on the ground or carry the leg entirely.
Stiffness after rest.Many dogs look worse getting up after a nap or first thing in the morning, then loosen up a little with movement.
Trouble rising, jumping, or using stairs.Hesitation at the couch, the car, or the stairs can be a frequent clue.
Swelling around the knee.You may feel thickening or firmness around the stifle compared to the other leg.
A popping or clicking sound.Some dogs develop an audible click when the joint is unstable or when the meniscus, a cushion inside the knee, is also injured.
The “sit test.”A classic sign is sitting with the injured leg kicked out to the side instead of tucked neatly under the body.
If you are trying to figure out how to tell if your dog tore its ACL at home, these dog cruciate ligament symptoms are a strong starting point. They are not a diagnosis. The next step is a proper orthopedic exam.
How a torn cruciate ligament is diagnosed
A veterinarian or surgeon confirms a cruciate tear with a hands-on orthopedic exam, feeling for abnormal movement in the knee. Your veterinary team may refer to this as cranial drawer or tibial thrust. Some dogs are tense or sore enough that light sedation helps the exam, and radiographs, or x-rays, are used to assess joint swelling, arthritis, bone structure, and surgical planning needs.
Because partial tears can be subtle, an exam by a team that focuses on orthopedics every day matters. Getting the diagnosis right the first time helps your dog receive the right treatment sooner, hopefully before the ligament tears completely. The TPLO surgery is reliable for preventing the partial ACL tear from becoming completely torn.
What to do next if you suspect a torn ACL
If you think your dog has a cruciate injury, start with three steps:
Restrict activity right away.Keep your dog quiet, leashed for bathroom breaks, and off stairs, furniture, and slippery floors. Avoid running, jumping, rough play, and uncontrolled activity until a professional has evaluated the knee.
Schedule an orthopedic evaluation early.Arthritis can develop in an unstable knee. While arthritis may progress even with treatment, stabilizing the joint can help protect long-term comfort and function.
Learn your treatment options.Conservative management may help control discomfort and improve function in some dogs short term, but it does not mechanically stabilize the knee. Because ongoing instability can contribute to arthritis progression and additional joint injury, surgery is commonly recommended. Many sources say surgery is more important for larger more active dogs; however, this is not true based on force plate gait analysis studies. Little dogs actually benefit just as much as big dogs, humans just fail to recognize the evidence and thus have created this stereotype. The best approach does NOT depend on your dog’s size, age, activity level, or severity of the current lameness. The best approach is to quantify where your dog is at in the degenerative process of ACL tearing (partial vs complete), the predisposing anatomy (tibial plateau slope TPS or Tibial plateau angle TPA), degree of instability, and other systemic diseases if present.
When dog ACL tear treatment involves surgery, two common options are TPLO(Tibial Plateau Leveling Osteotomy) and lateral suture stabilization, also called extracapsular repair. Lateral suture stabilization uses a strong suture outside the joint to help stabilize the knee while scar tissue forms.
TPLO is one of the most widely studied surgical options for canine cruciate disease and is often favored when more normal leg use outcomes are preferred. TPLO is not just for larger or more active dogs, it is for any dog that wants maximal restoration of stability within their stifle/knee joint. Rather than replacing the torn ligament, TPLO changes the biomechanics of the knee so the joint can function more stably without relying on the damaged ligament. This is because ligament replacement surgery as is done in humans will re-stretch or tear when performed in dogs due to the difference in TPS/TPA between a dog and a human.
To learn more about the TPLO procedure, watch this clinically accurate overview from TPLO Info, developed by one of our surgeons.
If we need to see inside the joint, we prioritize minimally invasive techniques that support precision while minimizing additional impact on healing. Arthroscopymay be recommended when there is concern for meniscal injury or other intra-articular damage, but it is not required for every cruciate case. The goal is to choose the right approach for each dog: stabilize the knee, address meaningful joint pathology when present, and protect recovery wherever possible.
Recovery does not end in the operating room. At VROC, we support healing with individualized post-operative guidance, activity restriction plans, rehabilitation and pain managementwhen appropriate, and tools that help protect recovery. For some patients, this may include options such as Lick Sleeveto help protect the surgical site or Strydeto support long-term joint health. Your surgical team will recommend what fits your dog’s procedure, temperament, mobility, and recovery plan.
Frequently asked questions about torn ACLs in dogs
Can a dog recover from a torn ACL without surgery?
It depends on your definition of “recover”. The most influential aspects of this injury towards predicting outcome are the amount of instability, TPA, and scar tissue formation present in the knee before complete ACL tearing. The outdated belief that non surgical outcomes are more successful in small, old less active dogs is an understatement. Smaller dogs appear to tolerate an unstable knee better than a large dog but this does not mean they are more comfortable. In fact small dogs may actually be bearing less weight on the affected leg as a percentage of body weight. Large or small, young or old every individual knee injury should be evaluated by a veterinarian skilled at knee instability assessment (drawer or preferably tibial thrust testing) before choosing to skip surgery.
Is it painful for a dog to live with a torn ACL?
Yes. Dogs rarely cry out, but persistent limping is a sign of pain or discomfort. Many dogs are very good at masking pain, so a quiet or stoic dog can still be hurting. Treating a cruciate injury is about restoring comfort, not only improving movement.
How long can a dog go with a torn ACL?
A dog can limp along on an untreated cruciate tear, but that is not the same as healing. The knee remains unstable, arthritis progresses, surrounding muscle weakens, and the opposite leg may take on extra load. There is no safe fixed timeline, which is why early evaluation is the safest next step.
Will my dog tear the other ACL too?
Dogs with cruciate disease in one knee have an increased risk of developing the same problem in the other knee (most people quote 60% chance within 2 years). That does not mean it will definitely happen, but it is one reason your surgical team may discuss weight management, conditioning, rehabilitation, and long-term joint support as part of your dog’s care plan.
Does every dog need arthroscopy during ACL surgery?
No. Arthroscopy is not required for every cruciate surgery, and joint exploration is not what stabilizes the knee. Procedures such as TPLO stabilize the joint by changing the biomechanics of the stifle. Arthroscopy may be recommended when there is a reason to evaluate the inside of the joint, such as concern for meniscal injury. When visualization is indicated, minimally invasive arthroscopy allows the surgeon to inspect intra-articular structures with less soft-tissue disruption than a traditional open approach.
Is it worth getting ACL surgery for dogs?
Yes, the long-term outlook after surgical stabilization is generally excellent. The most influential aspects of this injury towards predicting outcome are the amount of instability, TPA, and scar tissue formation present in the knee before complete ACL tearing. The outdated belief that non-surgical outcomes are more successful in small, old less active dogs is an understatement. Smaller dogs appear to tolerate an unstable knee better than a large dog but this does not mean they are more comfortable. In fact small dogs may actually be bearing less weight on the affected leg as a percentage of body weight. Large or small, young or old every individual knee injury should be evaluated by a veterinarian skilled at knee instability assessment (drawer or preferably tibial thrust testing) before choosing to skip surgery.
Cost is a fair question too: dog ACL surgery cost depends on the procedure, your dog’s size, and any related joint damage. Our team is glad to walk through pricing, recovery expectations, and financing optionsduring your visit.
Expert cruciate ligament care for dogs in Austin
VROC, Veterinary Regional Orthopedic Center, is a surgeon-owned hospital dedicated exclusively to orthopedic surgeryand spine carefor dogs and cats across Austin and Central Texas. Our board-certified surgeons treat cruciate injuries every day, from diagnosis through procedures such as TPLO and lateral suture stabilization, with focused support throughout recovery.
If you are seeing signs of a possible cruciate tear, the next step is clarity: a focused orthopedic evaluation, a confirmed diagnosis, and a treatment plan built around your dog’s unique needs.
