Librela and Solensia: What I’ve Learned About These Arthritis Drugs for Dogs and Cats

Arthritis is very common in older pets. It can make walking, jumping, and playing painful. Over the years, veterinarians have used many tools to help dogs and cats feel better. Two newer medications are Librela for dogs and Solensia for cats.

At first, these drugs seemed very promising. Over time, however, we have learned more, and that has changed how I use them.

What Does “Arthritis” Really Mean?

The word arthritis ends with “-itis,” which means inflammation.

So arthritis is not just about pain, it is a condition driven by ongoing inflammation inside the joint. This inflammation damages cartilage, irritates bone, and causes stiffness, swelling, and pain over time.

Pain is what we notice, but inflammation is often the engine driving the disease.

Why Inflammation Matters

Inflammation in arthritis can come from many sources, including:

• Joint wear and tear
• Old injuries
• Abnormal joint shape (e.g. hip dysplasia, elbow dysplasia)
• Mechanical instability (e.g. a torn cruciate ligament)
• Being overweight or obese

Extra body fat does more than add stress to joints. Fat tissue releases inflammatory chemicals that can increase inflammation throughout the body, including inside joints. This means weight plays a major role in arthritis progression, not just comfort.

How NSAIDs Help (link to my blog post on NSAIDs https://drbrunke.wordpress.com/wp-admin/post.php?post=551&action=edit)

NSAIDs (like carprofen, meloxicam, and others) help arthritis by:

• Reducing inflammation
• Decreasing pain
• Slowing inflammatory damage inside the joint

They work on the inflammatory process itself, which is why they have been a mainstay of arthritis treatment for decades.

How Librela and Solensia Are Different (see here for more detail: https://drbrunke.wordpress.com/wp-admin/post.php?post=560&action=edit)

Librela (for dogs) and Solensia (for cats) work by blocking nerve growth factor, or NGF.

NGF helps send pain signals through nerves. Blocking it can reduce pain, but:

• It does not directly treat joint inflammation
• It does not stop inflammatory damage
• At best, it may reduce neurogenic inflammation, which is inflammation linked to nerve signaling

Neurogenic inflammation is only one part of the overall inflammatory process in arthritis.

This is an important distinction: Reducing pain signals is not the same as treating the disease itself.

My Early Clinical Experience

When these medications were first released, I used them carefully in select patients.

I treated about 20 cats with Solensia between 2022 and 2023. Around two-thirds showed improvement, based on owner reports and mobility scoring.

My experience with Librela in dogs was more limited. I treated five dogs, and only two showed clear improvement.

At the time, this suggested these drugs might help some pets, especially cats.

What Studies Show About Pain Relief

Research shows that anti-NGF drugs reduce arthritis pain about as well as oral NSAIDs.

They are:

• Not stronger than NSAIDs
• Not more effective overall
• Simply a different way to manage pain

When two treatments help pain equally, safety becomes the deciding factor.

What We Learned From Human Medicine

Before these drugs were widely used in animals, similar anti-NGF drugs were tested in people with arthritis.

During human clinical trials, doctors saw serious problems in some patients, including:

• Rapid joint destruction
• Bone collapse
• Severe worsening of arthritis

This condition became known as rapidly progressive osteoarthritis (RPOA).

Because of these findings, the FDA stopped and banned anti-NGF drugs for use in people, even though they helped reduce pain.

This matters because people and animals share many of the same biological pathways.

What We Are Seeing in Dogs

As more dogs received Librela, veterinarians began reporting:

• Sudden weakness or trouble walking
• Ligament and tendon injuries
• Joint collapse and fractures
• Rapid worsening of arthritis

Some of these problems appeared months after treatment began, making them harder to recognize right away.

Importantly, these severe joint collapse reactions have not been reported in animals treated with NSAIDs, despite decades of widespread use.

What About Cats and Solensia?

Cats have generally shown fewer obvious joint collapse events, but that does not mean Solensia is risk-free.

NGF also plays a role in:

• Brain health
• Memory and learning
• Normal nerve function

Blocking NGF may:

• Affect cognitive function in senior cats
• Cause subtle nerve changes
• Speed up age-related brain decline

Because cats hide symptoms so well, these changes can be very difficult to detect.

For this reason, I also recommend caution when using Solensia, especially in older cats or those with possible neurologic or cognitive disease.

Why My Recommendation Changed

Based on:

• My clinical experience
• New biological research
• Human trial outcomes
• Post-approval safety reports

I no longer recommend Librela for dogs or Solensia for cats

NGF is not just a pain signal. It is a growth and repair factor that supports bones, nerves, and brain health. Blocking it may reduce pain, but it does not treat the full inflammatory disease of arthritis and it can introduce serious risks.

When Might These Drugs Still Be Considered?

In very limited situations, these medications may still be discussed for:

• End-stage arthritis
• Pets with very few remaining options
• Carefully screened patients
• Owners who fully understand the risks, including death and euthanasia

Even then, close monitoring is essential.

The Big Picture for Pet Owners

Arthritis care works best when it addresses inflammation, pain, and overall health. The strongest plans usually include:

• Weight management
• Physical rehabilitation
• Thoughtful use of anti-inflammatory medications
• Joint injections when appropriate
• Regular reassessment

If your dog or cat is receiving Librela or Solensia, or if you are considering them, I strongly encourage a detailed discussion with your veterinarian about what is being treated: pain, inflammation, or both.

Final Thought

Pain relief is important, but so is protecting joint health, nerve health, and brain health. As science evolves, recommendations must evolve too.

My guiding rule remains simple: do no harm.