Nonerosive, Immune-Mediated Polyarthritis in Dogs

 

Nonerosive immune-mediated polyarthritis is an immune-mediated inflammatory disease of the diarthroidal joints (movable joints: shoulder, knee, etc.), which occurs in multiple joints, and in which the cartilage of the joint (articular cartilage) is not eroded away. A type III hypersensitivity reaction, which causes antibodies to be bound to an antigen, in this case joint tissue, causes this condition.

 

These antibody-antigen complexes are called immune complexes, and they are deposited within the synovial membrane (where the fluid that lubricates the joints is held). There, the immune complexes trigger an abnormal immune response to the joint cartilage. What this means is that, in effect, the body is fighting against itself. This leads to an inflammatory response, and complement protein activation by the tissue surrounding the cartilage, in response to the immunity displaying cells, leading to the clinical signs of arthritis.

 

Symptoms

 

• Stiffness in legs
• Lameness
• Decreased range of motion
• Cracking of the joints
• Joint swelling and pain in one or more joints
• Joint instability, subluxation (partial dislocation) and luxation (complete dislocation)
• Often cyclic, comes and goes

 

Types

 

• Systemic lupus erythematosus: a noninfectious disease in which nuclear material from various cells becoming antigenic; autoantibodies (antinuclear antibodies) are formed to attack the body’s own joints
• Idiopathic polyarthritis: of unknown origin
• Polyarthritis associated with chronic disease: chronic infectious, neoplastic (uncontrolled growth of tissue), or enteropathic disease (intestinal disease)
• Polyarthritis-polymyositis syndrome: combination of arthritis in multiple joints, with weakness, pain, and swelling of the muscles
• Polymyositis syndrome: weakness, pain, and swelling of the muscles in the neck and legs
• Polyarthritis-meningitis syndrome: combination of arthritis in multiple joints with inflammation of the brain, with fever, pain, and stiff muscles
• Polyarthritis nodosa: arthritis in multiple joints with small nodular swellings
• Familial renal amyloidosis in Chinese shar-pei dogs: genetically predisposed condition causing deposits of hard, waxy protein fiber in the kidneys or surrounding area
• Juvenile-onset polyarthritis of Akita breed dog
• Lymphocytic-plasmacytic synovitis: swelling of the synovial membrane of the joint (where the lubrication for the joint is produced) as the result of antibody attack on the tissue

 

Causes

 

• Idiopathic (unknown)
• Immunologic mechanism likely: abnormal immune response to the system
• May occur secondary to a hypersensitivity reaction to sulfas, cephalosporins, lincomycin, erythromycin, and penicillins, involving the deposition of drug antibody complexes in the blood vessels of the synovium (lining of the joint)
• Chronic cases:
  • Antigenic stimulation along with concurrent meningitis (brain swelling)
  • Gastrointestinal disease
  • Periodontitis: infection of the tissues that support the teeth
  • Neoplasia: uncontrolled growth of tissue
  • Urinary tract infection
  • Bacterial endocarditis: bacterial infection of the heart lining
  • Heartworm disease
  • Pyometra: infection and accumulation of pus in the uterus
  • Chronic otitis media (infection of the middle ear) or external fungal infections
  • Chronic Actinomyces or Salmonella infections: bacterial infections, with fever, abscesses

 

 

Diagnosis

 

You will need to give your veterinarian a thorough history of your dog's health leading up to the onset of symptoms. Your veterinarian will perform a thorough physical exam on your dog, taking note of signs of pain, decreased range of motion, and any lameness. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, a urinalysis, and an electrolyte panel. In dogs suspected to have lupus erythematosus, a lupus erythematosus preparation or an antinuclear antibody test can be performed. Joint fluid aspirate will be taken for lab analysis, and submitted for bacterial culture and sensitivity. A biopsy (tissue sample) of synovial tissue will also help to make a definitive diagnosis.

 

X-ray images can also be used as a diagnostic tool. If a nonerosive, immune-mediated polyarthritis condition is present, it will be visible on the radiograph image.

 

Treatment

 

Physical therapy, including range-of-motion exercises, massage and swimming can help treat severe disease. For dogs that have a lot of difficulty walking, bandages and/or splints may be put around the joint to prevent it from further degrading. Weight loss will also help to decrease pressure on the joints if your dog is overweight. If your dog is on antibiotics your veterinarian will attempt to rule out a reaction to the antibiotics.

 

Surgery is only recommended to remove infection if your dog has a concurrent infection when diagnosed with the nonerosive polyarthritis.

 

Living and Management

 

Your veterinarian will schedule frequent follow-up appointments with your dog, but if its condition worsens, contact your veterinarian immediately. Remission is usually achieved in 2-16 weeks, but the recurrence rate jumps to 30-50 percent when therapy is discontinued.