When a dog’s ACL (or cranial cruciate ligament) breaks, the stifle (AKA knee) becomes painful, unstable, and prone to arthritis – causing a limp. It’s important to understand that there are many degrees of ACL tearing that can occur in dogs.

Here are some simple guidelines to follow:

If your dog is not putting any weight on the hind leg and is holding it up, then there is a very good chance they have a FULL tear of their ACL.
If your dog is just slightly limping or using the leg but not putting full weight on it, then there is a good chance they may have a PARTIAL tear of their ACL.

At the moment when the ACL tears, a dog will experience sudden pain and often hold their leg up. Depending on the severity of the tear, they may then avoid putting any weight on the leg for a day or so, and when they do use it again will have a limp that often continues for several weeks. If no treatment is given, typically at the end of several weeks the initial pain will have subsided and the dog will be more willing to use the leg.

However, it’s very important to understand that this does not mean the dog is completely cured. The joint remains unstable, and when your dog puts his weight on the leg, the tibia (shin bone) slides forward in relation to the femur (thigh bone). This can be painful for your dog as the joint cartilage wears down, and leads to arthritis – a serious chronic issue.

The bottom line is this: if your dog has a limp, don’t ignore it. Dogs are extremely stoic when it comes to pain, and just because it doesn’t seem to bother them that much doesn’t mean they’re not hurting.

Schedule a veterinary appointment immediately to get to the bottom of your dog’s limp. If your veterinarian does diagnose the cause as a torn ACL, surgery is often required. Given that this is such a common injury, several procedures have been developed over the years to repair the ligament. You can read everything you need to know about cruciate surgery here.

It’s so important that we’ll say it again: if your dog has a limp, don’t ignore it. Even if it starts to seem like they’re getting better, it doesn’t mean it won’t cause more serious chronic issues in the future. Schedule an appointment with your veterinarian as soon as possible to give your dog the best chance at a full and healthy life.