Effects of intra-articularly administered endotoxin on clinical signs of disease and synovial fluid tumor necrosis factor, interleukin 6, and prostaglandin E2 values in horses.

The research analyzes the impact of endotoxins introduced within the joint, on the clinical symptoms and various inflammatory factors in horses. It also studies the body’s systemic response to inflammation.

Experimental Procedure

The experiment was carried out on four horses in which sterile synovitis, a type of joint inflammation, was induced. This was achieved by injecting a lethal toxins, called lipopolysaccharide (LPS), into one joint of the horse. This procedure was designed to study the effects of an immune response triggered by bacterial infection locally within the joint.

• The toxin chosen was derived from a strain of bacteria called Escherichia coli, and the amount administered to each horse was 3 micrograms.
• The opposite joint was used as a control, and an equal volume of a saline solution was administered instead of the toxin.
• The joint fluid and blood samples were collected at different time intervals from 0 to 144 postinjection hours (PIH).
• For the initial 12 hours of the experiment, samples were collected via an indwelling catheter inserted inside the joint. After that, samples were obtained through a procedure called arthrocentesis (a minimally invasive procedure to collect fluids from the joint).

Analytical Procedure

The collected joint fluid was then analyzed for a variety of factors.

• Components such as cell counts, protein concentration, and cytologic variables were determined.
• The fluid was examined for the presence of certain chemicals associated with inflammation and immune response: tumor necrosis factor (TNF), interleukin 6 (IL-6), and prostaglandin E2 (PGE2).
• Blood samples were also analyzed for TNF and IL-6 activities and white blood cell count.
• Additionally, the skin temperature at the joint site was captured using a thermographic scanner before each sample collection, as a measure to monitor local inflammation.

Findings

The horses showed minimal systemic, or full-body, reactions to the induced inflammation in the joint. There was only a slight increase in rectal temperature and one horse showed signs of mild depression, but nothing significantly harmful. However, there were localized symptoms seen in the leg that received the toxin injection, including mild discomfort for a limited duration. The surface temperature of the treated joint also showed a significant increase, indicating inflammation at the injection site.