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Toxic Inflammation of the Joints in Dogs

Septic arthritis is a type of inflammation of the joint that is commonly seen after a traumatic injury that has exposed the joint to contamination by environmental microorganism, after surgery, or when microorganisms enter the joints through the blood stream. Infection of other body systems can be a source of these microorganisms ending up inside the joint fluid. Although infection of a single joint is common, more than one joint may be found to be affected in some dogs.

Septic arthritis is differentiated from arthritis by the lack of toxicity in the joint fluid. Arthritis is recognized by inflammation of one or more bone joints, and septic arthritis is the inflammation of the joint(s) together with the presence of a disease causing microorganism, usually bacterial, within the fluid of the affected joint(s).

This disease is commonly seen in male dogs between the ages of four and seven years. Predisposed breeds include German shepherds, Dobermans, and Labrador retrievers.

Symptoms and Types

• Pain
• Fever
• Lethargy
• Lack of appetite
• Joint swelling
• Lameness of the affected limb
• Affected joint is hot to the touch
• Inability to move the affected joint normally

Causes

Dogs with weakened or abnormal immune system or diabetes mellitus are at higher risk of developing various infections, including septic arthritis. Other underlying factors and/or causes include:

• Opportunistic infections after injury, bite wound (e.g., fight with another animal), gunshot wound, or surgery
• Bacterial infections that have traveled from another location in the body
• Fungal infections

Diagnosis

Dogs with this disease are usually presented to veterinarians with symptoms of lameness. Your veterinarian will take a detailed history, including any incidents of previous injury, animal fights, or other illnesses. A detailed physical examination will help your veterinarian to establish if single or multiple joints are affected. Other diseases that can cause lameness will also be considered.

Routine laboratory tests will include a complete blood count, biochemistry profile, and urinalysis. The results of most of these tests are usually found to be normal, except for the complete blood count, which may reveal the presence of infection and inflammation in the blood stream. X-rays of the affected joint are useful for finding changes pertaining to the inflammation. In dogs with chronic infection, changes in the joint structures will usually be apparent, including destruction of bone, irregular joint space, and abnormal bone formation -- all of which will be revealed in the X-rays.

The most important diagnostic test will be an analysis of the fluid that is taken directly from the joint. To obtain the joint fluid, your veterinarian will sedate or anesthetize your dog prior to the sample collection. This test will reveal the presence of an increased volume of fluid in the joint space, changes in the color of the fluid, the presence of a higher number of inflammatory cells, and also the causative bacteria. Your veterinarian may also recommend that a culture of a joint fluid sample be done in order to grow the causative microorganisms in the laboratory. This will confirm the diagnosis and may lead to a solution for how to treat the infection.

With patients in which infections of other body systems are suspected to be responsible for this disease, blood and urine samples will be taken for culture. If bacteria are present in the blood or urine, the culture test will allow for the growing of these bacteria and thus will help in establishing the diagnosis and treatment plan.

The earlier the treatment is given after the appearance of symptoms, the better the chances are for a complete resolution of the symptoms.