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Flashcards in Inflammatory arthritis Deck (39)
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1

Clinical presentation - inflammatory arthritis

- can be stilted/ crouched
- arthralgia (subtle to severe)
- may present as ataxia

2

What is the first investigation of arthralgia?

Cytological evaluation of joint flud to determine if purulent or sterile.
- If purulent, run C+S, suggests septic arthritis
- If sterile, C+S negative, run other tests (CBC, biochem, ultrasound, thoracic rads, echocardiography, further blood work)

3

Methods to investigate arthralgia

- rads.
- arthrocentesis
- synovial investigation
- systemic investigation (thorough PE, hx, CBC/ biochem)

4

Why might arthrocentesis be useful?

- to determine if septic vs. immune-mediated
- look for increased neutrophils (+/- lymphocytes)
- degenerate neutrophils = septic
- non-degenerate = immune-mediated

5

Why might rads. be useful for inflammatory arthritis dx?

- to determine if septic/ immune-mediated
- acute: normal (may be primary dz)
- sub-acute/ chronic: erosion of cartilage/ sub-chondral bone

6

Describe normal synovial fluid

- clear
- pale
- yellow
- high viscosity

7

Causes - septic arthritis

- haematogenous: from focus elsewhere
- traumatic (esp horses): lacerations, punctures
- Iatrogenic (often 'aseptic' procedures): intra-articular injections of PSGAG - rare, sx

8

Tx - septic arthritis - SA

- AB (amox/clav acid)
- no difference b/w sx and medical tx
- 94% infxn will resolve
- may need to remove implants d/t infxn
- 6wk course AB, based on culture results

9

Tx - septic arthritis - EQ

- acute infxn = emergency
- eliminate organisms from joint
- eliminate enzymes and mediators that cause cartilage destruction
- AB/ Through and through lavage/ arthrocopy and artrotomy
- intra-articular ABs, IV ABs (penicillin and gentamicin)
- resample joitn fluid every 48 hr
- oral AB
- AB on C+S, IV to start (amox/clav acid), possible local delivery (gentamicin, impregnated sponges), intrasynovial catheters. Tx even if negative C+S result if there is a response to empirical ABs.
- daily changed dressings for wounds
- early stages rest
- Px excellent if tx rapidly
- physio/hydro to reduce adhesions and prevent periarticular fibrosis

10

Px - septic arthritis - EQ

- increased with prompt recognition, aggressive tx and local AB
- other factors: intended use, structures involved, concurrent bone involvement

11

Define IMPA

Immune-mediated polyarthritis

12

Aetiology -IMPA

- Ab/Ag complex --> formation of inflammatory products
- Host IgG and M bind to altered autologous IgG
- Ag/Ab complex deposited on synovium --> neutrophil/ macrophage chemotaxis

13

Aetilogy - erosive IMPA

- cellular or humoral immunopathogenic factors
- release of chondrodesctuctive collagenases/ proteases
- failure of self-tolerance or production of immunogenic immunoglobulins
* plasma cells/ BCs --> RF --> synovium --> activated synoviocytes --> IL1, collagenases etc --> osteoclasts cause bone resorption and subchondral bone cysts --> pannus formation (i.e. GT formation) --> fibroblast proliferation leads to contracture and limb deformation

14

What are the autoimmune aspects of IMPA - 2

- clones of potentially autoaggressive cells originally inactivated in the thymus proliferate
- hypersensitivity reaction

15

Risk factors - autoimmune dz - 7

- hereditary component - beagles
- certain ifxn (GpA strep pharyngitis --> acute rheumatic fever)
- bacterial endocarditis
- discospondylitis
- IMBD
- neoplasia (various)
- chronic hepatitis

16

What is a type 1 hypersensitivity reaction?

- immediate/ anaphylactic reaction
- IgE --> mast cells, basophils

17

What is type 2 hypersensitivity?

- Ab-dependent cytotoxic reaction
- IgG or IgM against a cell-surface component

18

What is type 3 hypersensitivity?

- Immune-complex mediated reaction
- Large amounts of IgG or IgM plus Ag --> microprecipitates
- clinical manifestations depend on where complexes form/ lodge
- immune-mediated arthritis: immune-complexes generated locally (joint) or systemically or both

19

What is type 4 hypersensitivity?

- cell-mediated/ delayed-type reaction
- intra-cellular organism

20

Outline features of immune-mediated arthritis

- polyarticular dx (6+ joints), occasionally pauciarticular (2-5), rarely monoarticular (this is more likely septic arthritis)
- Chronic dz, d/t:
* continual or recurrent presence of inciting Ag
* failure of normal down-regulation when inciting Ags gone
* initial damage to host tissues resulting in exposure of altered self-antigens

21

Ddx - palmigrade stance (carpus sinking)

- carpal hyperextension injury
- IMPA
- endocrine dz (Cushings, both usually causes palmi- and planti- grade stance)

22

How to examine patient with suspect IMPA

- observe walking, stiffness, difficulty rising
- general PE - pyrexia, depression, anorexia
- palpation and manipulation +/- sedation
- ROM, pain, heat, swelling, crepitus, assess ligament laxity

23

With IMPA, how many animals tend to be lame vs. joint effusion?

- 35% lame
- 40% joint effusions

24

Causes non-erosive PA

- Type 1 (uncomplicated idiopathis) commonest = 50%
- Type 2 (associated with remote infections, reactive arthritis), 25%
- Type 3 (associated with GIT dz/ hepatic 15%)
- Type 4 (associated with remote neoplasia),

25

How to investigate non-erosive PA

- POLYARTHTOPATHY: arthrocentesis, joint rads., synovial biopsy
- UNDERLYING DZ HUNT: haematology, biochemistry, urinalysis, thoracic rads., abdominal ultrasound, other tests (CSF, serology, PCR)
- Joint radiography = usually not v interesting

26

List some other examples of non-erosive PA

- SLE
- Lyme disease (Borrelia burgdorferi)
- Drug associated (e.g. Dobies + sulphonamides)
- Caliciviral in kittens
- associated with SRMA = steroid-responsive meningitis-arteritis in adolescent dogs
- IBD
- vaccine induced (within 30d vaccine)

27

What can joint rads help you distinguish?

erosive vs. non-erosive arthritis

28

Describe erosive dz

- chronic synovitis --> production of proliferative GT (pannus)
- pannus invades articular cartilage and can erode subchondral bone
- pannus + inflamed synovium produce enzymes including proteases and collagenases --> further joitn destruction
- similar changes in septic arthritis
- accounts for 1% PA

29

Examples - erosive joint dz

- rheumatoid arthritis
- periosteal proliferative PA in cats
- PA of greyhounds (Felty' syndrome)
- Felty's syndrome - RA, splenomegaly, neutropaenia

30

How to diagnose RA

- system in humans, but is rarely applicable in animals
- must have seven of the below present, including two of 7, 8 and 10
1 stiffness after rest
2 pain
3 swelling of one joint
4 swelling of another joint (