Investigation of polyarthritis

Question 1

History q’s

Answer 1

• how long has this been going on?
• parasite control, esp flea and tick tx
• vaccination history
• where is the animal exercised?
• any other signs i.e non-lameness related?
• recent weight loss?
• animal ever been abroad?

Question 2

CE

Answer 2

• observe from distance
• watch move -> assess gait
• TPR, mm, etc as normal CE

Question 3

Ddx for multiple limb lameness & bilateral joint effusion

Answer 3

• polyarthritis (immune mediated or septic)
• septic polyarthritides (e.g. Borrelia infection [Lyme dz])
• inflammatory bone dz e.g. metaphysical osteopathy, panosteitis, hypertrophic pulmonary osteopathy (Marie’s dz)
• myositis/myopathy
• neuropathy
• other less likely causes of lethargy & reluctance to walk might include hypoglycaemia (but this doesn’t cause joint pain)

Question 4

Diagnostic approach

Answer 4

• routine bloodwork
• serum sample (serology)
• radiographs of affected limbs
• trial therapy
• joint taps

Question 5

Trial therapy

Answer 5

• NSAIDs to reduce pyrexia and any pain that appears to originate from limbs
• see again in 1-2d time

Question 6

Other than haematology, what test can you do to determine if there’s significant inflammatory dz?

Answer 6

• C-reactive protein (CRP) assay
  – rises rapidly when inflammation occurs
  – falls rapidly when it resolves
  – hence used to monitor therapy / course of inflammatory dz

Question 7

Types of immune mediated poly arthritis

Answer 7

• erosive (e.g. rheumatoid arthritis)
• non-erosive

Question 8

Use of serology

Answer 8

• for Borrelia
• for rheumatoid arthritis
• for systemic lupus erythematous (SLE) (multi-system dz)

Question 9

What is a marker for SLE?

Answer 9

• anti-nuclear factor

Question 10

Tx of immune mediated polyarthritis

Answer 10

• immunosuppressive doses of steroids
• analgesia: paracetamol or opiates

Question 11

How can you differentiate between septic and immune-mediated polyarthritis?

Answer 11

• synovial fluid culture

Question 12

What is type I immune-mediated polyarthritis?

Answer 12

• idiopathic

Question 13

How do some clinicians now classify polyarthritis due to difficulties in classifying some cases?

Answer 13

• primary (idiopathic) or secondary (reactive) with secondary encompassing formerly Type II, III, IV immune mediated polyarthritis classes + drug associated and those that may result from vaccination