Arthritis vs. ACL Tears: How to Tell the Difference
August 25, 2025
Key Takeaways:
- Arthritis Develops Slowly, ACL Tears Happen Suddenly: Arthritis causes gradual stiffness, while ACL tears result in immediate limping.
- Weight-Bearing Differences: Dogs with arthritis still use the affected leg, while ACL tears cause non-weight-bearing lameness.
- Diagnosis Methods: X-rays, knee stability tests, and MRIs help confirm arthritis or ACL injuries.
- Treatment Varies: Arthritis is managed with supplements, weight control, and therapy, while ACL tears often require surgery.
- Delaying Treatment Can Worsen Joint Damage: Untreated ACL tears can lead to arthritis, increasing long-term pain and mobility issues.
Is Your Dog Limping? Here’s How to Tell If It’s Arthritis or an ACL Tear
When dogs start limping, slowing down, or struggling to stand, pet owners often wonder: Is it arthritis, or could it be an ACL tear? Both conditions cause joint pain, stiffness, and mobility issues, but they require different treatments.
Understanding the key differences between arthritis vs. ACL tear in dogs can help you determine when to rest, provide joint support, or seek urgent veterinary care.
What Is Arthritis in Dogs?
Arthritis is a progressive joint disease that causes inflammation, stiffness, and pain. It develops over time, usually in senior dogs or those with a history of joint injuries.
📍Key Signs of Arthritis:
✔️ Gradual onset — Symptoms appear slowly over weeks or months.
✔️ Morning stiffness — Dogs struggle to move after resting but improve with light activity.
✔️ Sore, swollen joints — Inflammation makes movement painful.
✔️ Reduced activity levels — Dogs may hesitate to jump, run, or climb stairs.
✔️ Worsens in cold weather— Arthritis pain is often more noticeable in winter.
Arthritis is a long-term condition, but early management can slow progression and improve quality of life.
What Is an ACL Tear in Dogs?
An ACL tear (technically called a CCL tear in dogs) happens when the cranial cruciate ligament (CCL) in the knee is partially or fully ruptured. This injury is usually caused by sudden movement, excessive activity, or wear and tear over time.
📍Key Signs of an ACL Tear:
✔️ Sudden onset —Limping appears immediately after activity or injury.
✔️ Non-weight bearing — Dogs may hold up the affected leg.
✔️ Knee swelling — Inflammation is common near the joint.
✔️ Unstable gait — The knee may appear shaky or weak.
✔️ Toe-touching stance — Dogs may place their toes on the ground but avoid putting full weight on the leg.
A partial ACL tear may cause intermittent limping, while a complete ACL rupture will lead to severe lameness and joint instability.
Arthritis vs. ACL Tear in Dogs: Key Differences
| Feature | Arthritis in Dogs | ACL Tear in Dogs |
|---|---|---|
| Onset of Symptoms | Develops slowly over time | Happens suddenly after activity |
| Limping Severity | Starts mild, worsens over months | Immediate, often severe limping |
| Weight-Bearing | Dogs still put weight on the leg | Dogs avoid weight on the injured leg |
| Joint Swelling | Mild to moderate over time | Swelling appears quickly after injury |
| Pain Triggers | Worse after rest, improves with movement | Painful with any movement |
| Common In | Senior dogs, overweight dogs | Active dogs, large breeds |
| Treatment Approach | Joint supplements, pain meds, weight management | Surgery often needed for complete tears |
When to See a Veterinarian
🚨Signs That Require Immediate Veterinary Attention:
✔️ Sudden severe limping
✔️ Complete inability to bear weight
✔️ Swollen, inflamed knee joint
✔️ Persistent lameness lasting more than a few days
✔️ Popping sounds from the knee.
🚨If your dog’s limping is gradual and worsens over months, it’s likely arthritis. However, if they suddenly start limping after exercise, it may be an ACL tear.
Diagnosing Arthritis vs. ACL Tear in Dogs
Veterinarians use physical exams and imaging tests to determine whether arthritis or an ACL tear is the cause of your dog’s pain.
🚨Common Diagnostic Methods:
✔️ X-rays – Identifies arthritis, swelling, and bone damage.
✔️ Drawer Test & Tibial Thrust Test – Checks for knee instability (specific to ACL tears).
✔️ MRI or CT Scan – Provides a detailed view of ligament injuries.
✔️ Joint Fluid Analysis – Helps confirm arthritis diagnosis.
If your dog has an ACL tear, early treatment is essential to prevent long-term joint damage.
Treatment Options for Arthritis vs. ACL Tears in Dogs
Both arthritis and ACL injuries require different treatment plans.
Treatment for Arthritis in Dogs:
✔️ Joint supplements – Glucosamine, chondroitin, and omega-3s reduce inflammation.
✔️ Pain management – NSAIDs, acupuncture, or laser therapy.
✔️ Weight control – Extra weight adds pressure to joints.
✔️ Gentle exercise – Helps keep joints mobile without excessive strain.
✔️ Hydrotherapy & physical therapy – Builds strength without impact.
Treatment for ACL Tears in Dogs:
✔️ Strict rest & limited activity – Essential for recovery.
✔️ Pain medication & anti-inflammatories – Reduces swelling.
✔️ Surgery (TPLO, TTA, or Lateral Suture Repair) – Best for full ACL tears.
✔️ Physical therapy – Strengthens muscles post-surgery.
While arthritis is manageable long-term, an ACL tear may require surgery for full recovery—especially for active dogs.
Can an ACL Tear Lead to Arthritis?
Yes! An untreated ACL tear can lead to secondary arthritis, which causes chronic pain and stiffness. When the knee is unstable for too long, cartilage wears down, leading to permanent joint damage.
💡This is why early diagnosis and treatment are so important!
Is It Arthritis or an ACL Tear? Let’s Find Out Together.
If your dog is limping, slowing down, or avoiding activity, it’s time to get expert advice. Not sure whether it’s arthritis vs. ACL tear in dogs? A professional exam can give you the answers you need.
📞 Concerned about your dog’s joint pain? Schedule a consultation at Heron Lakes Animal Hospital today.
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Because your dog deserves a pain-free, active life!