Does Every Small Dog with a Torn ACL Need Surgery? The Evidence Says… Maybe Not.

Why Conservative Management May Be a Reasonable Option for Some Small Dogs with Cranial Cruciate Ligament Disease

By Steve Mehler, DVM, DACVS

For decades, the diagnosis of a torn cranial cruciate ligament (CCL)—the canine equivalent of the human ACL—has almost automatically led to one recommendation:

Surgery.

And for many dogs, particularly large and athletic breeds, that's still the right answer.

But what about a 9-pound Yorkshire Terrier?

A 12-pound Maltese?

A 14-pound Miniature Poodle?

Should every small dog with a torn CCL automatically undergo a TPLO or another surgical stabilization procedure?

The answer, according to the current literature, is not necessarily.

A growing body of evidence suggests that carefully selected small dogs may achieve meaningful improvement without surgery, provided they receive structured conservative management.

This doesn't mean surgery isn't beneficial. It often is.

It simply means that the decision may not be as straightforward as we've traditionally believed.

Why Surgery Became the Standard

The cranial cruciate ligament is one of the primary stabilizers of the canine stifle (knee).

When it ruptures, the tibia shifts forward during weight bearing—a phenomenon known as cranial tibial thrust.

This instability leads to:

• Pain

• Lameness

• Meniscal injury

• Progressive osteoarthritis

• Muscle loss

For larger dogs, instability is substantial, and decades of research have demonstrated that procedures such as the Tibial Plateau Leveling Osteotomy (TPLO) provide excellent functional outcomes.

As a result, surgery gradually became the default recommendation for almost every dog diagnosed with CCL disease.

But an important question remained:

Does the same evidence apply to dogs weighing less than 15 kilograms?

The Literature Says We Don't Really Know

A recent comprehensive review published in the Journal of Small Animal Practice examined exactly this question.

The authors evaluated the available literature regarding treatment of cranial cruciate ligament disease in dogs weighing less than 15 kilograms (33 pounds).

Their conclusion was surprising.

There is currently very little high-quality evidence identifying the optimal treatment for small dogs with cranial cruciate ligament disease.

That's an important distinction.

It doesn't mean surgery isn't effective.

It means we have far less evidence proving that every small dog benefits from surgery to the same degree as larger dogs.

For years, we've often extrapolated recommendations from Labrador Retrievers, German Shepherds, and Golden Retrievers to dogs weighing one-tenth as much.

The review concluded that conservative management should remain a reasonable treatment option for carefully selected patients, although recovery is generally slower, averaging approximately four months.

Why Small Dogs Are Different

This concept makes sense when you think about biomechanics.

Imagine a suspension bridge.

The heavier the load crossing the bridge, the greater the forces placed on its support cables.

The same principle applies to the canine knee.

A Labrador Retriever generates dramatically greater forces across the stifle than a Chihuahua.

Lower body weight means:

• Less cranial tibial thrust

• Reduced joint instability

• Less stress on secondary stabilizing structures

• Greater opportunity for scar tissue (periarticular fibrosis) to provide functional stability

In other words, small dogs simply ask less of their knees.

Many also have lower athletic demands.

Most owners aren't expecting a 10-pound Maltese to compete in agility or dock diving.

They simply want their dog to walk comfortably through the house, enjoy neighborhood walks, and maintain a good quality of life.

This Isn't a New Idea

Interestingly, this concept has existed for decades.

In 1984, orthopedic surgeon Dr. Peter Vasseur published one of the landmark studies on conservative treatment of cranial cruciate ligament rupture.

He found that:

• Dogs weighing less than approximately 15 kilograms frequently regained acceptable limb function without surgery.

• Larger dogs had significantly poorer outcomes with conservative treatment.

That paper helped establish something orthopedic surgeons still recognize today:

Body size matters.

New Evidence Continues to Support Individualized Decision-Making

More recently, investigators prospectively compared TPLO surgery with conservative management in dogs weighing less than 10 kilograms.

The results were fascinating.

Both groups experienced significant improvements in:

• Pain

• Limb function

• Quality of life

The dogs that underwent TPLO maintained greater muscle mass, an important finding because muscle plays a major role in joint stability and long-term mobility.

However, from the owner's perspective, both treatment groups experienced meaningful clinical improvement over the short term.

This suggests that while surgery offers advantages, it may not always be essential to achieve a satisfactory outcome in carefully selected small dogs.

Conservative Management Is Not "Doing Nothing"

One of the biggest misconceptions about non-surgical treatment is that it simply means waiting.

Nothing could be further from the truth.

Successful conservative management requires an active treatment plan that typically includes:

Weight Management

Maintaining a lean body condition is one of the most important predictors of success.

Even small increases in body weight substantially increase forces across the knee.

Controlled Exercise

Complete inactivity is rarely beneficial.

Instead, activity is gradually increased using structured leash walks while avoiding uncontrolled running, jumping, and rough play.

Rehabilitation Therapy

Rehabilitation may include:

• Sit-to-stand exercises

• Weight shifting

• Balance exercises

• Underwater treadmill therapy

• Passive range-of-motion exercises

• Strengthening exercises

The goal is preserving muscle while allowing biological stabilization to occur.

Pain Management

Many patients benefit from:

• NSAIDs

• Cryotherapy

• Anti-NGF monoclonal antibodies (when appropriate)

• Other multimodal analgesic strategies

Comfortable dogs move more normally, helping preserve muscle mass and joint function.

Which Small Dogs Might Be Good Candidates?

Based on the available evidence, conservative management deserves serious consideration in dogs that are:

✔ Under 10–15 kilograms

✔ Older or relatively sedentary

✔ Living primarily as companion pets

✔ Experiencing partial ligament tears

✔ At increased anesthetic risk

✔ Owned by families unable to pursue surgery

Each patient should still undergo a complete orthopedic examination because concurrent meniscal injury, severe instability, or other complicating factors may shift the balance toward surgery.

When Surgery May Still Be the Better Choice

Conservative treatment isn't appropriate for every small dog.

Surgical stabilization should remain strongly considered for dogs that:

• Have complete rupture with marked instability

• Develop meniscal injury

• Remain persistently lame despite conservative management

• Are highly athletic or working dogs

• Need the fastest possible return to function

Procedures such as TPLO, TTA, or lateral suture stabilization often provide faster recovery, improved mechanical stability, and better preservation of muscle mass.

Shared Decision-Making Is the Future

Perhaps the most important lesson from the literature is that treatment shouldn't be dictated by a single diagnosis.

Instead of asking:

"Does every small dog need surgery?"

A better question is:

"Will this individual dog benefit enough from surgery to justify the additional cost, recovery, and anesthetic risk?"

That's the essence of evidence-based medicine.

It recognizes that there isn't always a single correct answer.

There are often multiple reasonable options.

The Bottom Line

For decades, surgery has been considered the default treatment for cranial cruciate ligament rupture.

While this remains true for many larger dogs, the evidence in small dogs is less definitive.

Current research suggests that carefully selected dogs weighing less than approximately 10–15 kilograms can experience meaningful improvements in pain, function, and quality of life with conservative management, although recovery is typically slower and surgical stabilization may better preserve muscle mass.

The goal shouldn't be to operate on every dog—or avoid surgery whenever possible.

The goal should be to match the treatment to the individual patient, using the best available evidence to guide the decision.

Because good medicine isn't about following dogma.

It's about asking the right questions.

And sometimes, the best answer isn't the one we've always given.

References

1. Vasseur PB. Clinical results following nonoperative management for rupture of the cranial cruciate ligament in dogs. Veterinary Surgery. 1984;13:243–246.

2. Aragon CL, Budsberg SC. Applications of evidence-based medicine: Cranial cruciate ligament injury repair in the dog. Veterinary Surgery. 2005;34:93–98.

3. Bergh MS, Sullivan C, Ferrell CL, et al. Systematic review of surgical treatments for cranial cruciate ligament disease in dogs. Journal of the American Animal Hospital Association. 2014;50:315–321.

4. Journal of Small Animal Practice. Comprehensive review of cranial cruciate ligament disease in dogs under 15 kg (2025/2026 review). (Discusses the limited high-quality evidence supporting one optimal treatment strategy and concludes that conservative management remains a reasonable option in selected patients.)

5. Prospective comparison of TPLO versus conservative management in dogs weighing less than 10 kg. Veterinary Surgery. 2024.

6. Millis DL, Levine D. Canine Rehabilitation and Physical Therapy. 3rd ed. Elsevier.

7. Cook JL. Cranial cruciate ligament disease in dogs: Biology, biomechanics, and current treatment recommendations. Veterinary Surgery.

This is exactly the kind of topic where evidence-based medicine shines—not by saying surgery is unnecessary, but by recognizing that patient size, lifestyle, degree of instability, owner goals, and the quality of the evidence all matter.