Nonerosive, Immune-Mediated Polyarthritis in Cats
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 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.
- Stiffness in legs
- 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
- Shifting leg lameness (in cats) - usually the stifle (knee), elbow, carpus (wrist), and tarsus (part of the ankle joint) are affected
- 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
- 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
- Proliferative form of feline chronic progressive polyarthritis (FCPP): rapid spreading of polyarthritis
- 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)
- The feline leukemia virus (FeLV, and feline syncytium-forming virus (FSFV) are linked to cats with Feline chronic progressive polyarthritis
- Chronic cases:
- Antigenic stimulation along with concurrent meningitis (brain swelling)
- Gastrointestinal disease
- Neoplasia: uncontrolled growth of tissue
- Urinary tract infection
- Periodontitis: infection of the tissues that support the teeth
- 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
You will need to give your veterinarian a thorough history of your cat's health leading up to the onset of symptoms. Your veterinarian will perform a thorough physical exam on your cat, 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. 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.
Physical therapy, including range-of-motion exercises and massage can help treat severe disease. If your cat is having a lot of difficulty walking, bandages and/or splints may be put around the joint to prevent it from further degrading. Weight loss can also help to decrease pressure on the joints if your cat is overweight. If your cat is on antibiotics your veterinarian will attempt to rule out a reaction to the antibiotics.
Surgery is only recommended to remove infection if your cat has a concurrent infection when diagnosed with the nonerosive polyarthritis.
Living and Management
Your veterinarian will schedule frequent follow-up appointments with your cat, 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.
A record of body structures using an x-ray
A product made of fluid, cell waste, and cells
A medical condition in which the ear becomes inflamed
The term for the joint between the femur and tibia (knee cap)
A medical condition in which the smooth muscles become inflamed
The displacement of the bone from its joint
The hollow bodily organ that holds the embryo and fetus and provides nourishment; only found in female animals.
An in-depth examination of the properties of urine; used to determine the presence or absence of illness
A medical condition in which the synovial membrane becomes inflamed
A medical condition in which the meninges becomes inflamed
The dislocation of a bone from the joint
a) inhaling b) getting out fluid or gas by the act of sucking.
A medical condition in which the joints become inflamed and causes a great deal of pain.
Any substance or item that the body of an animal would regard as strange or unwanted; a foreign disease or virus in the body (toxin, etc.)
The process of removing tissue to examine it, usually for medical reasons.
An inflammation of the lining of the heart
An increase in the number of bad white blood cells
Any type of pain or tenderness or lack of soundness in the feet or legs of animals
A reaction to a certain pathogen that is out of the ordinary
A protein in the body that is designed to fight disease; antibodies are brought on by the presence of certain antigens in the system.