Lameness and Corrective Measures

April 21, 2019

What is lameness?

Lameness refers to an inability to properly use one or more limbs. It is most often associated with pain or injury. The most common causes of acute or sudden lameness in dogs are injury to a joint, bone fracture or dislocation. Osteoarthritis and hip dysplasia may also cause lameness in dogs. Lameness can affect dogs and cats of any age from growing puppies to senior dogs.

  • Puppies and kittens – lameness may be caused by growth abnormalities or by injury
  • Adult Dogs and cats – limb injuries sometimes occur without any history of an accident or trauma
  • Senior Dogs and cats – Degenerative joint disease (DJD) or arthritis are the most common causes of lameness

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My dog suddenly developed lameness and there is no obvious cause on examinations or x-ray. What can be done?

Lameness of unknown origin is common in dogs of all types and sizes. If only they could talk!  Depending on the severity and duration, additional tests such as blood and urine tests to look for an infectious cause may be required. In some cases, a trial with anti-inflammatory medications may be necessary. Your veterinarian will determine the best course of action based on your pet’s condition and the results of diagnostic tests.

Testing for Lameness

What might be causing my pet’s lameness?

The most common cause of lameness is trauma or injury to joints, ligaments, tendons, muscle or bone. Other causes of lameness include developmental diseases in young animals, degenerative joint disease in older pets, immune-mediated joint disease, infectious joint diseases, neurological disorders, and cancer of the bones or joints.

How do we determine the cause of a pet’s lameness?

knee_joint

Finding the cause of a pet’s lameness usually starts with a completehistory and physical examination. Your pet’s “history” of illness includes details such as whether the lameness occurred suddenly or came on gradually, whether trauma was involved, whether more than one limb is affected, whether the lameness is constant or comes and goes, and whether there are other signs of illness. The physical examination includes assessment of the pet’s overall health as well as close inspection of the affected limb(s) or joint(s). The veterinarian is looking for evidence of trauma such as bruising or wounds, as well as signs of soreness such as swelling, heat, redness, pain, or reduced ability to move a joint or limb.

What diagnostic tests are commonly done in a pet with lameness?

  1.  If a pet appears to be healthy except for lameness, the first diagnostic test will likely be to take x-rays of the sore area. If there is joint pain, then joint fluid analysis may also be recommended.
  2. If pain is found only in the knee of the hind leg, a ruptured or torn anterior cruciate ligament (ACL) may be the cause. When the ACL is damaged, the knee joint becomes loose and moves in an abnormal way called a drawer sign. The drawer sign is more easily detected when the leg is completely relaxed, and therefore the test is often done with the pet under sedation or light general anesthesia. 
  3. If the pet has additional signs of illness, such as fever, poor appetite, lethargy, or weight loss, then underlying systemic illness may be present and screening tests may be recommended. Screening tests are a series of simple tests that assess the overall health of a pet. The most common screening tests include a complete blood count (CBC), a serum biochemistry profile, and a urinalysis.  

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How is joint fluid obtained?

Before collecting joint fluid, the skin over the joint is shaved and carefully scrubbed as if for surgery. Joint fluid (also called synovial fluid) is collected by passing a fine sterile needle through the skin into the joint space and then attaching a small syringe, and pulling out, or aspirating, a small amount of synovial fluid. Immediately after collection, a small amount of synovial fluid is spread thinly on one or more microscope slides and quickly air-dried. Any remaining fluid is placed in a sterile sample tube and sent along with the slides to the laboratory for analysis. 

How does joint fluid analysis help?

Joint fluid analysis can be very helpful in identifying the cause of lameness. At the laboratory, the amount of protein in the fluid is measured. The fluid is also examined microscopically by a veterinary pathologist to see how many cells are present, and to identify what types of cells are there. If the protein content of the joint fluid is higher than normal or there are too many cells in the fluid, then joint inflammation is likely present. The types of cells found may explain the cause of the inflammation. For example, high numbers of neutrophils (pus cells) suggest either bacterial infection of the joint or immune-mediated joint disease, and increased numbers of mononuclear cells (white blood cells seen in longstanding inflammation) are associated with degenerative joint disease. Occasionally, there may be evidence of damaged cartilage or previous bleeding in the joint; sometimes infectious organisms or tumor cells may be seen.

What additional diagnostic tests might be done on joint fluid?

jointslide_cliented

If bacterial infection is suspected, culture and sensitivity of the joint fluid may be recommended. This test helps to identify bacteria that might be causing lameness and indicates which antibiotic should be used to treat the infection.  

What other diagnostic tests might be done?

Depending on the results of the history, physical exam and screening tests, specific blood tests may be recommended to diagnose infectious diseases, such as Lyme disease, Ehrlichiosis, or fungal infection etc., that cause lameness. There are also specific antibody tests, such as the rheumatoid factor test that can help to confirm a diagnosis of immune-mediated joint disease.

If X-rays reveal a mass or an area of abnormal-looking bone, then fine needle aspiration or surgical biopsyof the area may be recommended to determine if there is inflammation, infection, or cancer.   

If my dog continues to be lame, will he be on medication forever?

Not necessarily. Most of the time, we are able to accurately diagnose the cause of lameness and provide your pet with specific treatment. Some forms of lameness such as osteoarthritis require lifelong medical treatment while others require surgical repair.

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Ernest Ward, DVM

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