Osteoarthritis in our dog and cat companions

Geriatric pet care

Our canine and feline companions are living long active lives well into their geriatric years. Therefore assessing and treating osteoarthritis is an important part of geriatric pet care. Many pet owners make the comment that they believe arthritis is the cause of stiffness and a slow rising from rest in their pets.  Up to 60% of dogs are diagnosed with the disease based upon radiographic evidence at some time in their life.

As with most medical conditions, treatments for osteoarthritis are specifically targeted to the physiologic processes that cause the disease.  At Carlson Animal Hospital we strive to educate pet owners about the physiologic basis of the treatments we employ. In this blog we will delve into a bit more detail about the disease itself.

Osteoarthritis and the synovial joints

Osteoarthritis is a chronic, degenerative disease that affects synovial joints.  Synovial joints are articular joints between two bones that are joined by a joint capsule containing fluid and cartilage. The purpose of synovial joints are to allow smooth movement between two bones. The term arthritis, without the osteo prefix, refers to inflammation of a joint of any sort.  Whereas osteoarthritis refers to the chronic degenerative process of cartilage breakdown and associated inflammation.

cat being examined for osteoarthritis

Dr. Swindell examining a feline patient.

Osteoarthritis affects both dogs and cats.   Sometimes the disease is related to aging and sometimes it is not.  Osteoarthritis may also occur secondary to an injury or instability of a joint. A common orthopedic injury in dogs is a rupture of an anterior cruciate ligament (also known as an ACL rupture).

dog hip examination

Dr. Swindell performing a hip exam.

Hip dysplasia is an instability of the hip joint that is often diagnosed earlier in life. These pets will eventually develop osteoarthritis in that joint due to the chronic instability/inflammation.

Physiology of osteoarthritis

Moving on to the physiology of osteoarthritis. We’ve included a definition of a few key terms:

  1. Cartilage– firm, smooth, flexible connective tissue found inside the surface of a joint.
  2. Chondrocyte – a cell that creates the matrix of the cartilage that is found inside cartilage.
  3. Hyaluronate and Chondroitin sulfate – polysaccharides associated with cartilage that are the joint’s shock absorbers.
  4. Inflammatory mediators – signals sent by cells in the body as a response to damage- they cause the body’s protective response, including inflammation. (This is a very simplified discussion of a very complex process!)

The primary pathology of osteoarthritis is cartilage breakdown.  The cartilage becomes weaker, less elastic with less ability to absorb shock.  Small fissures within the cartilage develop propagating a self-perpetuating degenerative process.  Enzymes are produced that degrade the chondroitin, hyaluronate and the collagen of the cartilage further.  As the cartilage is degraded the fluid in the joint secretes inflammatory mediators which cause inflammation inside the joint.  As the osteoarthritis progresses,  osteophytes ( new bone formation) occur around the joint.  These are little outgrowths of bone that occur near where there is damaged cartilage. These osteophytes further create a decreased range of motion and pain.  Osteophytes have sometimes been described as bone spurs.

dog hip with osteoarthritis damage

Model of a normal canine hip joint on the left and a hip joint with osteophytes and chances from osteoarthritis on the right.

Diagnosis includes a physical exam and radiographs (X-rays)

We believe that it is important to diagnose osteoarthritis prior to beginning treatment, especially since the treatment and the disease are frequently chronic.  The initial portion of the diagnosis is based upon a physical examination of the pet.  Joints with osteoarthritis often have a decreased range of motion with associated pain upon careful manipulation.  Radiographs (x-rays)  of the affected joints are advised.  While radiographs will not show us damaged cartilage, they will document the osteophytes that occur in the advanced stages of osteoarthritis, as well as an increase in joint fluid if present,  which is usually associated with inflammation and discomfort. The radiographs below demonstrate a normal canine knee joint on the left.  A radiograph of a knee joint with osteophytes (the osteophytes are noted as small irregularities along the margins of the larger bones surrounding the joint) and osteoarthritis on the right.

dog's knee radiograph

A dog’s normal knee joint – no osteophytes.

dog knee arthritis radiograph

A dog’s arthritic knee joint with osteophytes.

 

 

 

 

 

 

 

 

Multi-modal treatment

At Carlson Animal Hospital we employ a multi-modal approach to the treatment of osteoarthritis.  This means that we target the disease based on the various physiologic processes you  just learned about in this blog.  We decrease inflammation with medication, we help build and support cartilage with supplements, we incorporate a moderate exercise program and weight loss program.  We can even employ a very safe and effective drug that helps decrease the enzymes that cause the breakdown of chondroitin and collagen.

By using all these tools,  we can actually modify the course of the disease, rather than just decreasing pain and stiffness.  We continually re-assess management options based upon the current research through the medical literature and medical conferences.  Fortunately, we continue to see treatment options which increase the comfort of pets affected by osteoarthritis, and decrease the speed of the process of cartilage breakdown.

Our Doctors would be pleased to speak with you about these treatment options and whether they may be helpful to your four legged family members.

It is our pleasure to serve you and your pets. Please do not hesitate to call our offices if you have any questions or concerns. Thank you for allowing us to be a part of your veterinary healthcare team.

www.carlsonanimalhospitals.com

Carlson Animal Hospital, Oak Park, IL 708.383.3606


 

 

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