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Vetdle Archive

Archive Case #208: Canine Immune-Mediated Polyarthritis

Dog veterinary case - Medium - September 27, 2026

Clinical Clues

  1. Finn, a four-year-old dog, was booked in for left forelimb lameness. Today, his right hindlimb seems worse.
  2. He is reluctant to get up, has a fever, and has no reported injury.
  3. Several carpal and tarsal joints are swollen and painful, rather than just one limb.
  4. Radiographs show soft-tissue swelling without erosive bone changes.
  5. Fluid sampled from three joints contains many nondegenerate neutrophils. No organisms are seen on cytology.
  6. Joint-fluid cultures collected before antibiotics are negative, and infectious investigations tailored to travel and exposure history are unrevealing. The combined findings support non-erosive, immune-mediated inflammation affecting multiple joints.

Diagnosis

Canine Immune-Mediated Polyarthritis

Shifting lameness, fever and several inflamed joints support IMPA after infectious causes are investigated. Negative cytology or culture alone cannot exclude infection. These findings do not establish an idiopathic subtype; secondary triggers still need investigation. Remember: Fever with shifting lameness warrants examination of several joints.

Learning review

Review the case evidence

Use the paired clues to explain how the evidence in this dog case supports the provided diagnosis, Canine Immune-Mediated Polyarthritis, then compare your reasoning with the case explanation.

Evidence checkpoints

Clues 1-2

  1. Clue 1: Finn, a four-year-old dog, was booked in for left forelimb lameness. Today, his right hindlimb seems worse.
  2. Clue 2: He is reluctant to get up, has a fever, and has no reported injury.

Clues 3-4

  1. Clue 3: Several carpal and tarsal joints are swollen and painful, rather than just one limb.
  2. Clue 4: Radiographs show soft-tissue swelling without erosive bone changes.

Clues 5-6

  1. Clue 5: Fluid sampled from three joints contains many nondegenerate neutrophils. No organisms are seen on cytology.
  2. Clue 6: Joint-fluid cultures collected before antibiotics are negative, and infectious investigations tailored to travel and exposure history are unrevealing. The combined findings support non-erosive, immune-mediated inflammation affecting multiple joints.

Self-review prompts

  1. After clues 1-2, what evidence from this dog case shaped your initial interpretation?
  2. When you compare clues 3-4 with clues 1-2, what changed in your reasoning about Canine Immune-Mediated Polyarthritis?
  3. How do clues 5-6 align with the case explanation for Canine Immune-Mediated Polyarthritis?

Educational Use

Vetdle archive cases are educational veterinary games for diagnostic reasoning practice. They do not provide veterinary advice, diagnosis, treatment, or professional medical guidance.