Inflamatory Arthritis Flashcards
What is often seen with inflammatory OA? ECHOOOO
PUO
How can immune mediated v. septic processes be differentiated?
> arthrocentesis
- neutrophils degenerate if septic
- poportion of nucleated/mononuclear/neutrophils different
changes on radiography with both
- subacute/chronic : eroision of cartilage and sunchondral bone
Causes of septic arthritis
> haematogenous - foal umbilicus - intestine > traumatic - esp. horses > Iatrogenic (often "aseptic") IA injections, surgery etc.
What bacteria is the most common cause of eptic arthritis iatrogenicaly?
Staph aureus
- forms a glycocalyx on implants especially. (titanium more resistant)
Tx SA inflammatory arthitis?
- ABx (amoxy-clav 20mg/kg IV)
- no differnece between medical and sx tx
- 95% infections will resolve
- may need to remove implants
- 6 week Abx based on culture
Tx equine septic arthritis? Px?
- acute infection = emergency
- eliminate organisms from joint
- eliminate enzymes and mediators causing cartilage destruction
- Abx/through and thorugh lavage
- Arthoscopy/arthrotomy
- IA Abx, IV Abx (pen and gent)
- resample joint fluid q48hrs
- oral Abx
> C+S but IV to start with amoxyclav - can deliver locally (gentamicin impregnated sponges, intrasynovial catheters)
> early stages : rest - Px excellent if tx rpadily but only 50% return to racing
- Physio/ hydrtherapy to reduce adhesions and pevent periarticular fibrosis
Aetiology of IMPA?
- Ag/Ab complex -> formationi of inflammatory products
- Host IgG and M bind to altered autlogous IgG
- Ag/Ab complexes deposited on synovium -> neutrophil/macrophage chemotaxis
[Erosive] - cellular or humoral immunopathogenic factors - release of chondrodestructive collagenases/proteases
- failure of self-tolerance
- production of immunogenic immunoglobulins
Outline path of Rheumatoid arthritis
- Plasma cells/B lymphocytes -> RF factor
- Synoviocytes in the synovium are activated
- IL1, collagenases produced
- Osteoclasts -> bone resorption and subchondral bone cyts
- Pannus formation
- > fibroblast proliferation leads to contracture and limb deformation
Outline autoimmune pathophysiolgy
> mistake 1
- immune systems fails to recognise self
- clones of potentially autoaggressive cells originally inactivated in thymus proliferate
mistake 2
- inappropriate reaction doesn’t know when to stop
= hypersensitivity
Risk factors for autoimmune dz?
- hereditary (eg. beagles)
- certain infections (GpA strep pharyngitis -> acute rheumatic factor)
- bacterial endocarditis (full PE!!)
- discospondylitis
- immune mediated bowel disease
- neoplsia
- chronic hepatitis
What are the 4 types of hypersensitivity reactions? Which type causes IMPA?
> 1: immedite/anaphylactic
- IgE, mast cells and basophils
2: Ab dependent cytotoxic
- IgG, IgM against a cell surface component
3: immune complex mediated
- Large amonts of IgG or M + Ag -> microprecipitates
- cause of IMPA (precipitates lodge in joint or are created in joint)
4: cell-mediated, delayed type
- INtra-cellular organisms
Typical presentation of immune-mediated arthritis?
- Polyarticular disease (>6 joints) usually
- occasionally pauciarticular (2-5)
- rarely mono-articular
> if single joint affected but culure negative try empirical Abx tx - chronic dz
Outline immune-mediated arthritis process
- continual or recurrent presence of inciting antigens
- failure of normal down-regulation when incititing antigens gone
- initial dmagae to host resulting in exposire of altered self Ag
Causes of a palmigrade stance?
> traumatic hyper-extension injuries
palmigade likley to be more severely afected (erosive dz)
systemic disease (eg. Addisons??) all 4 limbs
palmar fibrocartilage damage
autoimmune disease
What may be fond on clinicla exam with immune mediated joint disease?
- multisystem pyrexia
- depression
- anorexia
- ligament slackening
4 types of non-erosive polyarthritis? Most common? LOOK UP
> 1: uncomplicated idiopathic
- most common
- early RA?
- severe signs
2: reactive arthritis (assoc with remote infections)
- endocarditis/urogenital
- severe signs
3: reactive arthritis (assoc with GI/hepatic dz)
- less severe signs
4: reactive arthritis (assoc with remote neoplasia)
- less severe signs
Invstigation of polyarthritis
> polyarthropathy - arthrocentesis - joint ads - synovial biopsy > underlying dz hunt - haem, biochem, urinalysis - thoracic rads - abdo ultrasound - other tests (CSF? Serology? PCR?)
Radiographic signs of immune mediated arthitis?
- joint effusion with cranial displacement of the fat pad
- not very excited
Egs. of other Non-Erosive polyarthritis?
- SLE
- Lyme dz
- Drug-associated (eg. Dobies, sulphonamides, penicillin, phenobarb)
- Vax induced (seen within 30d of vax)
- Calicivirus kittens
- Steroid-responsive meningitis-arteritis in adolescent dogs
- IBD
Why are rads important when they are rarely exctiing for immne mediated arthritis?
- r/o erosive disease
> much poorer prognosis (but rare!)
Outline pathophysiology of erosive disease. How common is erosive dz?
- chronic synovitis -> production proliferative granulation tissue (PANNUS)
- pannus invades articular cartilage and can erode subchondral bone
- pannus and inflamed synovium produce enzymes (proteases, collagenases) -> destruction
- similar changes in septic arthritis
> 1% of PA
Types of erosive joint disease?
- rheumatoid arthritis
- periosteal proliferative polyarthritis in cats
- polyarthritis of greyhounds (Felty’s syndrome in humans: RA
Is classic RA diagnosis applicable to animals? What shold be looked for?
> rarely applicable to animals (dont have nodules, rarely abnormal synovial fluid) - stiffness after rest - pain - swelling of one joint + another within 3mo - symmetrical joint swelling - subcut nodules - rad signs of eroision - RF + serology - abnormal synovial fluid - synovial histology - nodule histology > theoretically should have 7 of these inclusing 2/3 of erosion, RF+ and synovial histology
Radiogrpahic changes seen with erosive joint disease?
- subchondral bone erosion
- destructive symmetric multi-joint arthropathy
- early may be only soft tissue changes
- chronic: collapse of joint spaces, joint deformity or sub-luxation, peri-articular new bone formation, calcification of peri-articular soft tissues
Dx of RA?
- R/O SLE with ANA test (though SLE generally non-eroisive, RA erosive)
- 75% cases have high levels circlating R fator
- some dogs can have both SLE and RA
General principles of Tx of RA?
> NB. septic arthritis can -> 2* immune mediated arthritis , in these cases DO NOT IMMUNOSUPPRESS
- identify inciting factor and remove/tx
- modify lifestyle to decrease joint stress
- control inflame/suppress immune response
- analgesia
- NB. RA and multisystemic dz (SLE) often need more aggressive and prolonged tx than uncomplicated PA
- may be able to stop tx, may not
What must be remembered if tx animal that has been on NSAIDS?
Need wash out period before immunosupressive drugs started
What is the key drug for tx of IMPA? Other tx?
PREDNISOLONE
+- cytotoxic drugs (BM suppressino)
- cyclophosphamide (haemmorhagic cystitis, use for
What may happen with high dose steroids?
- induces palmigrade stance!! Iatrogenic Cushings
Tx rickettsial dz?
Doxycycline
Does azathrioprene need tapered dosing schedule?
NO
If combination protocol for IMPA used, which drug should be tapered first?
- one with greatest side effects
Monitoring tx of immune-mediated arthrits?
- response within 7d
- suubstancial decrease in WBCs and neutroophils is a good prognostic indicator
- type 1 :56% cured 13% relapsed 18% lifelong tx
> if clinically well, potentially no need to retap? Sometimes ta will still be +, dillemmaaaa!
Aspect to consider wrt surgical tx of inflammatory joint disease?
> manage pain in chronic dz
- persistnet inflam can -> joint subluxation
- synovectomy
- arthrodesis/excision arthroplasty/total joint replacement
cost, morbidity and surgical failure
- d/t ongoing dz in other joints
- effects of therapeutic agents on healing and infection
What is crystal-bsed arthritis?
= True gout
- in species that dont have the enzyme uricase (huans, birds, reptiles)
- reptils asscoaited with renal failure -> v urate excretion
- white periarticular deposits (urate crystals)
- > inflammatory reaction
- Lethargic iguana = suspect gout!*
Clinical signs with inflammatory arthritis
- stilted/crouched
- neurological gait (ataxia)
- arthralgia (subtle -> severe)
Tx of crystal-based arthritis in reptiles?
- fluid tx
- avoid meds that ^ renal excretion
5 main key points when thinking about inflammatory arthritis?
- multi-system involvmenet (pyrexia, stiffness +- joint pan and lameness)
- Type 3 hypersesntivity Ag-Ab complexes
- Commonest is type 1 immune-mediated polyarthritis (idiopathic)
- Differentiate between erosive and non-erosive dz for PROGNOSIS
- Immunosuppressive drugs (prednisolone) poss for life
