IMA may present in two forms. The first is a rare primary erosive form (rheumatoid arthritis), where there is loss and destruction of articular cartilage and subchondral bone. The other more common presentation is a non-erosive arthritis where there is little articular cartilage destruction.
Both forms involve production of antibody-antigen immune complexes within the synovial fluid.
- - Rheumatoid arthritis
- - Idiopathic erosive polyarthritis
- - Erosive polyarthritis of greyhounds
- - Type I: idiopathic — no identifiable cause
- - Type II: reactive — infection/inflammation not associated with joints
- - Type III: enteropathic/hepatopathic — gastrointestinal or hepatic disease
- - Type IV: paraneoplastic — neoplasia not associated with joints
- - Vaccine-induced (such as rabies, canine distemper virus) - time of vaccination unrelated to onset of disease
- - Drug-induced (e.g. potentiated sulphonamides)
- - Systemic lupus erythematosus (SLE), particularly in Nova Scotia duck tolling retrievers
- - Steroid-responsive meningitis-arteritis - 30% of IMP dogs have cervical pain associated with SRMA
- - Secondary to infections with Escherichia coli, Staphylococcus spp, Streptococcus spp, Mycoplasma spp, Fusobacterium spp, Erysipelothrix rhusiopathiae, Borrelia burgdorferi, Ehrlichia canis, Anaplasma phagocytophilum, Rickettsia rickettsii, Blastomyces spp, Cryptococcus spp, Histoplasma spp, Coccidioides immitis and Leishmania spp
- - Polyarthritis/polymyositis syndrome (Cocker spaniel)
- - Polyarthritis/meningitis syndrome (Weimaraner, Bernese Mountain Dog, German Short-Haired Pointer)
- - Polyarteritis nodosa (young beagles)
- - Juvenile polyarthritis of Akita Inus
- - 'Shar Pei fever' — amyloidosis and 'swollen-hock syndrome'
Clinical signs associated with this disease include acute onset of anorexia, lethargy, fever, limb stiffness, joint swelling, crepitus and pain, marked muscle atrophy, lymphadenopathy and rapid weight loss.
Diagnosis is based on clinical signs, characteristic joint fluid analysis and elimination of potential joint infection.
Blood tests are usually unrewarding, but a leukocytosis, nonregenerative anemia, increased alkaline phosphatase and hypoalbuminemia may be observed occasionally.
Arthrocentesis of joints often yields grossly cloudy synovial fluid with decreased viscosity. Cytological analysis presents frequently as a sterile fluid with increased cellularity.
Serial arthrocentesis and synovial fluid examination can be used to monitor treatment efficacy.
Treatment of underlying infectious agents is essential for resolution of disease. Approximately 10% of cases are non-responsive to therapy and require euthanasia.
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- Downs Vet
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