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
Lack of appetite
Lameness of the affected limb
Affected joint is hot to the touch
Inability to move the affected joint normally
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
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.
After taking the blood and joint fluid samples and confirming a diagnosis of bacterial infection, antibiotics will be given to counter the infection. Which antibiotic will work best for your dog will depend on the results of the culture and sensitivity testing, both of which will tell your veterinarian about the microorganism involved in the joint infection.
The affected joint may need to be drained and washed to avoid further joint damage. In patients with chronic joint infections, surgery may be required to remove the debris and wash and clean the joint. A catheter is usually placed during surgery to allow continuous drainage for few days.
Arthroscopy — a type of endoscope that is inserted into the joint through a small incision — is another technique that can be used to allow for a close examination of the interior of the joint, and can also sometimes be used in the treatment of the interior of the joint. Compared to surgery, arthroscopy is a less invasive technique.
Identifying the source of the infection is very important for a successful and permanent resolution of the symptoms. If an infection is found in any other area of the body system, especially if it is found to be the source of the joint disease, treating the primary infection will as important as treating the joint infection. Your veterinarian may also take samples on daily basis from the fluid coming out of the joint to see if the infection is still present within the joint or not. Once fluid has stopped seeping from the affected joint the catheter will be removed.
Living and Management
The use of alternating cold and heat packing on the affected joint will help in promoting the blood flow and decreasing the swelling, thus promoting healing. This can be done at home. Your veterinarian will advise restricted movement for your dog until a complete resolution of the symptoms has been achieved. If it is difficult to keep your dog confined to one place, you may consider cage rest for a short time. Trips outdoors for bladder and bowel relief should be kept short and easy for your dog to handle during the recovery period.
If necessary, your veterinarian will also brief you on the proper care of the catheter that has been placed in your dog’s affected joint. Though many patients respond well to antibiotic therapy, in a few patients the infection may be more stubborn and long-term antibiotic treatment may be required. Affected dogs usually respond to antibiotic treatment within 24-48 hours, but it may take 4-8 weeks or longer for some patients.
Even if the symptoms do subside quickly, it is essential to finish the full course of the prescribed medications in order to ensure that the infection does not rebound.