How Do I Know If My Dog Tore His ACL? 10 Clear Signs to Watch For

Dog with torn ACL

Has your furry friend suddenly started limping? Are they reluctant to put weight on one of their back legs? You might be wondering, “how do I know if my dog tore his ACL?” As a pet parent, it’s scary to see your dog in pain, and ACL injuries are unfortunately common in our canine companions.

I’ve been through this exact situation with my Lab mix, Cooper, and I know how worrying it can be. That’s why I’ve put together this comprehensive guide to help you identify if your dog might have torn their ACL (or CCL, as it’s technically called in dogs).

What Is a Dog’s ACL Anyway?

Before we dive into symptoms, let’s get clear on what we’re talking about. In dogs, the anterior cruciate ligament is actually called the cranial cruciate ligament (CCL), but most people still refer to it as the ACL. This ligament connects the femur (thigh bone) to the tibia (shin bone) and plays a crucial role in stabilizing your dog’s knee joint.

The CCL in dogs has three main jobs

• Preventing the tibia from sliding forward relative to the femur
• Preventing hyperextension of the knee
• Stopping the tibia from rotating internally

When this ligament tears, it creates instability in the joint that causes pain, inflammation, and difficulty moving.

10 Warning Signs Your Dog Might Have Torn Their ACL

1. Sudden Lameness

The most common and obvious sign of a torn ACL is limping on the affected hind leg. Your dog might be running in the yard one minute and suddenly yelp and start holding up their leg the next. This lameness can be mild to severe and may improve slightly with rest, only to worsen again with activity.

In Cooper’s case, he was chasing a squirrel in our backyard when I heard him yelp He immediately started holding his back right leg up and wouldn’t put any weight on it

2. Decreased Activity Level

Has your once-energetic pup become a couch potato? A noticeable decrease in activity level often accompanies ACL injuries. Your dog might be:

• Reluctant to jump onto furniture
• Hesitant to climb stairs
• Less enthusiastic about walks
• Lagging behind on previously enjoyable activities

3. Sitting Abnormally

Here’s a quick test you can try at home: ask your dog to sit. A healthy dog will typically sit squarely with both knees bent evenly. However, a dog with an ACL injury often sits awkwardly with the affected leg extended outward rather than tucked underneath them. This position, sometimes called “lazy sitting,” reduces pain by avoiding full flexion of the injured knee.

4. Stiffness, Especially After Rest

Dogs with ACL injuries commonly show stiffness particularly after periods of rest. You might notice

• Difficulty getting up in the morning
• Stiffness after naps
• Limping for the first few steps before “warming up”

5. Swelling Around the Knee Joint

Swelling around the knee joint is another common sign of an ACL tear. The swelling may be subtle initially but can become more noticeable over time.

To check for swelling, compare both of your dog’s knees side by side. Look for any differences in size or shape. The injured knee may appear larger or more rounded than the healthy one.

6. Pain When Touching the Area

Dogs with ACL injuries often show pain when the knee area is touched or manipulated. Your dog might:

• Whimper when the area is touched
• Pull away when you examine the leg
• Become protective of the injured limb
• Show changes in behavior due to pain

7. Muscle Atrophy

With chronic ACL injuries, the muscles in the affected leg begin to waste away due to decreased use. This muscle atrophy becomes noticeable when comparing the thigh muscles of the injured leg to those of the healthy leg. The injured leg will typically have less muscle mass, while the healthy leg may develop larger muscles from compensating.

8. Audible “Clicking” Sounds

Some dogs with ACL tears may have a concurrent meniscus injury, which can cause a clicking sound when the knee moves. If you hear clicking or popping when your dog walks or when the leg is manipulated, this could be a sign of a knee injury.

9. Thickened Stifle (Medial Buttress)

In dogs with chronic ACL issues, a firm, fibrous thickening called a “medial buttress” can develop on the inside of the tibia at the level of the knee joint. This thickening is often detectable during a physical exam and indicates long-standing inflammation.

10. Loss of Range of Motion

Dogs with ACL tears frequently experience decreased range of motion in the affected joint. Your veterinarian can assess this during an examination, but you might notice your dog seems unable to fully extend or flex the leg.

ACL Tear vs. Sprain: What’s the Difference?

It’s important to understand the difference between a torn ACL and a sprained ACL, as the treatment approach can differ significantly.

Breeds Most at Risk for ACL Injuries

While any dog can tear their ACL, certain breeds appear to be at higher risk:

• Labrador Retrievers
• Golden Retrievers
• Rottweilers
• Newfoundlands
• German Shepherds
• Boxers
• Bullmastiffs
• St. Bernards
• Akitas
• Chesapeake Bay Retrievers

Larger breeds generally have a higher risk, but even small dogs can experience ACL injuries.

How Vets Diagnose a Torn ACL

If you suspect your dog has torn their ACL, a veterinary examination is necessary for proper diagnosis. Here’s what you can expect:

1. Physical Examination

Your vet will first take a thorough history and perform a physical exam. They’ll assess your dog’s gait, palpate the knee joint, and check for signs like swelling, pain, and instability.

2. Specific Tests for Joint Stability

Vets typically perform two key tests to check for ACL tears:

• Cranial Drawer Test: The vet places one hand on the femur and the other on the tibia, then tries to move the tibia forward. In a dog with a torn ACL, the tibia will move abnormally forward, like a drawer opening.

• Tibial Compression Test: The vet flexes the hock (ankle) while palpating the knee. If the ACL is torn, the tibia will shift forward abnormally.

These tests might be difficult to perform on an awake dog due to pain and muscle tension, so sedation is sometimes required for an accurate assessment.

3. Diagnostic Imaging

X-rays are commonly used to support the diagnosis and rule out other conditions like bone cancer. While X-rays can’t directly visualize the ACL (since it’s soft tissue), they can reveal secondary signs of an ACL tear, such as joint fluid accumulation and bone changes.

In some cases, more advanced imaging like MRI or arthroscopy might be recommended for a definitive diagnosis.

What to Do If You Suspect an ACL Tear

If your dog is showing signs of an ACL injury, here’s what you should do:

1. Restrict Activity: Limit your dog’s movement to prevent further injury. No running, jumping, or stairs if possible.

2. Contact Your Vet: Schedule an appointment as soon as possible for proper diagnosis.

3. Keep Your Dog Comfortable: Provide a soft, supportive bed in an easily accessible location.

4. Follow Veterinary Advice: Never give human pain medications to dogs as many are toxic. Only use medications prescribed by your vet.

5. Consider a Support Harness: For larger dogs, a rear support harness can help them move around while taking weight off the injured leg.

Treatment Options for ACL Injuries

The treatment approach depends on several factors including the size of your dog, severity of the injury, your dog’s activity level, and your financial considerations.

Conservative Management

For small dogs (under 33 pounds) with partial tears, conservative management might be an option:

• Strict rest for 6-8 weeks
• Anti-inflammatory medications
• Joint supplements
• Physical therapy
• Weight management

Surgical Options

For most medium to large dogs and those with complete tears, surgery is typically recommended. Common surgical procedures include:

1. TPLO (Tibial Plateau Leveling Osteotomy): This procedure changes the angle of the tibial plateau to create stability without the ACL. It’s often recommended for large, active dogs.

2. TTA (Tibial Tuberosity Advancement): Similar to TPLO, this surgery involves moving a piece of the tibia to create stability.

3. Lateral Suture Technique: This less invasive procedure uses a strong suture outside the joint to mimic the function of the ACL.

4. Extracapsular Repair: Places sutures outside the joint to stabilize it.

Our Experience with Cooper’s ACL Tear

When Cooper tore his ACL, I was devastated. Our vet recommended TPLO surgery due to his size (75 pounds) and active lifestyle. The recovery was challenging – 8 weeks of strict rest, cone-wearing to prevent licking the incision, and short leash walks only for potty breaks.

It wasn’t easy keeping an energetic Lab calm, but following our vet’s instructions was crucial for his recovery. We used puzzle toys and chews to keep him mentally stimulated while physically restricted.

Today, 2 years later, Cooper runs and plays like nothing ever happened. The surgery was expensive (about $4,500), but seeing him happy and active again made it worth every penny.

Preventing ACL Injuries

While not all ACL injuries can be prevented, you can reduce the risk by:

• Maintaining a healthy weight: Obesity quadruples the risk of ACL tears.
• Regular, appropriate exercise: Keep muscles strong but avoid excessive jumping or twisting activities.
• Joint supplements: Glucosamine, chondroitin, and omega-3 fatty acids may support joint health.
• Non-slip flooring: Prevent slips and falls by using rugs or toe grips on slippery floors.

Final Thoughts

Dealing with a potential ACL tear in your dog can be stressful, but knowing the signs can help you seek treatment early. Remember, the sooner the condition is addressed, the better the outcome typically is.

If you’re noticing any of these symptoms, don’t wait – contact your veterinarian for proper diagnosis and treatment recommendations. Every dog is different, and your vet can help you determine the best approach for your specific pet.

Have you dealt with an ACL tear in your dog? What treatment option did you choose? Share your experience in the comments below to help other pet parents going through the same challenge!