Joint Cartilage Erosion in Cats

Erosive, Immune-Mediated Polyarthritis in Cats

Erosive, immune-mediated polyarthritis is an immune-mediated inflammatory disease of the joints, in which the cartilage of the cat’s joint (articular cartilage) is eroded away.

Leukocyte cells, leukocyte enzymes (catalyzing reactions), cell-mediated immunity, immune complexes (an antibody bound to its triggering antigen), and autoallergic reactions are all directed against cartilage components. This leads to an inflammatory response by the tissue surrounding the cartilage, and protein activation (complement) in response to the immunity displaying cells.

Destructive enzymes, which are released from inflammatory cells, damage the articular cartilage, synoviocytes (cells which produce a lubricating fluid, called synovia, for the joints), and chondrocytes (cartilage cells), leading to erosive changes in the joints.

The condition or disease described in this medical article can affect both dogs and cats. If you would like to learn more about how this disease affects dogs, please visit this page in the PetMD health library.

Symptoms and Types

Symptoms for cats are often cyclic, coming and going at random intervals. These symptoms include:

  • Lameness (ocassionally shifting-leg lameness)
  • Stiffness in walk
  • Decreased range of motion
  • Cracking of the joints
  • Joint swelling and pain in one or more joints
  • Joint instability, subluxation, and luxation

The typical onset of immune-mediated erosive polyarthritis in cats is from one to five years of age and the most common type of the disease is feline chronic progressive polyarthritis (FCCP).


The suspected causes for this form of joint cartillage erosion are T lymphocyte effector cells that carry out the attack response, and an abnormal antigenic response to the host antibody. That is, an immune response to a substance that stimulates production of antibodies, an antigen, which acts as a “trigger.” Other known causes include:

  • Idiopathic
  • Feline leukemia virus (FeLV) and feline syncytium-forming virus (FSFV) — both of which have been linked to cats with feline chronic progressive polyarthritis (FCPP)


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 of synovial tissue will also help to make a definitive diagnosis.

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


Removal of the bone through surgical means


A type of leukocyte in the body


A record of body structures using an x-ray


The displacement of the bone from its joint


An in-depth examination of the properties of urine; used to determine the presence or absence of illness


The dislocation of a bone from the joint


The term for the joint between the femur and tibia (knee cap)


An increase in the number of bad white blood cells


a) inhaling b) getting out fluid or gas by the act of sucking.


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.


Loss of epithelium to the basement membrane


A protein in the body that is designed to fight disease; antibodies are brought on by the presence of certain antigens in the system.


Any type of pain or tenderness or lack of soundness in the feet or legs of animals


White blood cells that are known for destroying disease and help to keep foreign substances out of the blood

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