Dog Immune-Mediated Polyarthritis

Immune-mediated polyarthritis causes joint pain across multiple joints; recognition and immunosuppressive treatment dramatically improve quality of life.

Key Facts

Immune-mediated polyarthritis (IMPA) is the most common cause of inflammatory joint disease in dogs.
It can occur as a primary condition or secondary to infection, neoplasia, or other immune-mediated disease.
Affected dogs show shifting leg lameness, reluctance to move, joint swelling, and fever.
Diagnosis requires joint fluid analysis confirming inflammatory cell populations.
Treatment with prednisolone alone achieves remission in most cases within 4-8 weeks.

Welfare Considerations

Dogs with IMPA experience pain in multiple joints simultaneously — the shifting lameness presentation reflects this diffuse, moving discomfort. Fever compounds the malaise, and severely affected dogs may be prostrate and unwilling to walk. The welfare impact is acute and significant. The good news is that response to immunosuppressive treatment is typically rapid and dramatic; most dogs show substantial improvement within days of starting prednisolone. Treatment must continue until full remission is achieved and then gradually tapered to prevent relapse. Underlying infectious causes should be sought and treated. Dogs with refractory disease may require additional immunosuppressants and specialist investigation.

What You Can Do

Seek veterinary assessment promptly for any dog showing reluctance to move, stiff gait, or joint swelling with fever.
Request joint fluid analysis if your vet suspects polyarthritis to confirm the diagnosis.
Complete the full prednisolone tapering course under veterinary guidance to reduce relapse risk.
Monitor for signs of relapse during and after tapering, including returned lameness or fever.