Polyarthritis in pets - Causes, diagnosis & treatment

Polyarthritis is an inflammatory condition in which multiple joints are affected simultaneously. It can occur in both dogs and cats and often leads to pain, stiffness, fever, reduced appetite, and lameness. The condition has several possible causes, including autoimmune diseases, infections, and secondary inflammatory reactions to other underlying conditions, such as gastrointestinal or skin conditions, and in some cases tumors.

In this article, we discuss the causes, symptoms, diagnosis, treatment, and prognosis of polyarthritis in pets.

What is polyarthritis?

Polyarthritis literally means "inflammation of multiple joints." It is often an immune-mediated condition, in which the animal's immune system attacks its own joints. The condition can be acute or chronic and can range from mild to severely disabling.

Which animals are at risk?

Polyarthritis occurs in both dogs and cats, but is clearly diagnosed more often in dogs. In dogs, there appears to be a breed-related predisposition, with Retrievers, German Shepherds, Akitas, Shar-Peis, and Greyhounds, among others, potentially having an increased susceptibility. In cats, polyarthritis occurs more often in association with underlying infectious diseases, such as feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV), but also in association with feline calicivirus or as a rare post-vaccinal reaction.

Causes of polyarthritis

The causes are diverse and can be divided into:

• Immune-mediated: autoimmune diseases in which the immune system attacks the joints
• Infectious: bacteria, viruses, or fungi that cause an inflammatory reaction
• Secondary: a reaction to other diseases such as tumors, gastrointestinal, urogenital infections, or dermatological conditions
• Idiopathic: with no identifiable cause

Symptoms in dogs and cats

Symptoms can vary, but common signs include:

• Stiffness and lameness that often affects multiple legs
• Pain when moving or when the joints are touched
• Swelling and warmth around the joints
• Fever and general malaise
• Reduced appetite and lethargy

Diagnosis of polyarthritis

The diagnosis is made based on a combination of clinical examination, blood tests, and imaging. In addition, joint fluid aspiration with analysis of the joint fluid can provide clarity about the type of inflammation. Additional tests may be needed to identify underlying causes such as infections or autoimmune diseases.

Treatment of polyarthritis

Treatment depends on the cause. For immune-mediated polyarthritis, anti-inflammatory drugs and immunosuppressants (such as corticosteroids or ciclosporin) are often used. For infectious polyarthritis, antibiotics are indicated. Secondary polyarthritis requires treatment of the underlying cause.

Recovery and prognosis

The prognosis varies greatly depending on the cause and the speed of treatment. For idiopathic or immune-mediated forms, long-term medication may be needed, sometimes for life. However, with good treatment, quality of life can improve considerably. For infectious forms, the prognosis is often favorable with timely therapy.

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