Immune-mediated arthritis

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Immune mediated dog arthritis of tarsus in a Golden Retriever dog showing characteristic joint swelling[1]
Chronic immune-mediate polyarthritis in a dog[2]

Immune-mediated polyarthritis (IMP) is a common non-infectious immune-mediated arthritis characterized by inflammatory, purulent changes to the canine joint[3].

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.

Causes include:

  • Erosive
- Rheumatoid arthritis
- Idiopathic erosive polyarthritis
- Erosive polyarthritis of greyhounds
  • Non-erosive
- Type I: idiopathic — no identifiable cause
- Type II: reactive — infection/inflammation not associated with joints[4]
- 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[5]
- Drug-induced (e.g. potentiated sulphonamides)
- Systemic lupus erythematosus (SLE), particularly in Nova Scotia duck tolling retrievers
- Steroid-responsive meningitis-arteritis[6] - 30% of IMP dogs have cervical pain associated with SRMA[7]
- Secondary to infections with Escherichia coli, Staphylococcus spp, Streptococcus spp, Mycoplasma spp, Fusobacterium spp, Erysipelothrix rhusiopathiae[8], Borrelia burgdorferi, Ehrlichia canis, Anaplasma phagocytophilum[9], 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[10].

Diagnosis is based on clinical signs, characteristic joint fluid analysis and elimination of potential joint infection[11].

Blood tests are usually unrewarding, but a leukocytosis, nonregenerative anemia, increased alkaline phosphatase and hypoalbuminemia may be observed occasionally[12].

Arthrocentesis of joints often yields grossly cloudy synovial fluid with decreased viscosity. Cytological analysis presents frequently as a sterile fluid with increased cellularity.

A differential diagnosis would include septic arthritis, age-related osteoarthritis[13], panosteitis, osteomyelitis, hypertrophic osteodystrophy, hypertrophic osteoarthropathy and osteosarcoma.

Treatment involves immediate analgesia with drugs such as carprofen, buprenorphine, meloxicam, tramadol or gabapentin.

Following relief of immediate joint pain, long-term prednisolone (1 mg/kg once daily) or leflunomide (3 - 4 mg/kg once daily for 6 weeks)[14] is required.

Serial arthrocentesis and synovial fluid examination can be used to monitor treatment efficacy[15].

Treatment of underlying infectious agents is essential for resolution of disease. Approximately 10% of cases are non-responsive to therapy and require euthanasia.

References

  1. Dog Diseases
  2. Downs Vet
  3. Johnson KC & Mackin A (2012) Canine immune-mediated polyarthritis: part 1: pathophysiology. J Am Anim Hosp Assoc 48(1):12-17
  4. Stull JW et al (2008) Canine immune-mediated polyarthritis: Clinical and laboratory findings in 83 cases in western Canada (1991–2001). Can Vet J 49:1195–1203
  5. Clements DN et al (2004) Type I immune-mediated polyarthritis in dogs: 39 cases (1997-2002). J Am Vet Med Assoc 224(8):1323-1327
  6. Wilbe M et al (2009) MHC class II polymorphism is associated with a canine SLE-related disease complex. Immunogenetics 61(8):557-64
  7. Webb AA et al (2002) Steroid-responsive meningitis-arteritis in dogs with noninfectious, nonerosive, idiopathic, immune-mediated polyarthritis. J Vet Intern Med 16(3):269-273
  8. Seelig U et al (2010) Septic polyarthritis caused by Erysipelothrix rhusiopathiae in a dog. Vet Comp Orthop Traumatol 23(1):71-73
  9. Kjelgaard-Hansen M et al (2006) Use of serum C-reactive protein as an early marker of inflammatory activity in canine type II immune-mediated polyarthritis: case report. Acta Vet Scand 48:9
  10. Wilson-Wamboldt J (2011) Type I idiopathic non-erosive immune-mediated polyarthritis in a mixed-breed dog. Can Vet J 52(2):192-196
  11. Johnson KC & Mackin A (2012) Canine immune-mediated polyarthritis: part 2: diagnosis and treatment. J Am Anim Hosp Assoc 48(2):71-82
  12. Stull JW et al (2008) Canine immune-mediated polyarthritis: clinical and laboratory findings in 83 cases in western Canada (1991-2001). Can Vet J 49(12):1195-1203
  13. Hegemann N et al (2005) Cytokine profile in canine immune-mediated polyarthritis and osteoarthritis. Vet Comp Orthop Traumatol 18(2):67-72
  14. Colopy SA et al (2010) Efficacy of leflunomide for treatment of immune-mediated polyarthritis in dogs: 14 cases (2006-2008). J Am Vet Med Assoc 236(3):312-318
  15. Berg RI et al (2009) Effect of repeated arthrocentesis on cytologic analysis of synovial fluid in dogs. J Vet Intern Med 23(4):814-817