In this study, we investigated the kinetics of tumor necrosis factor (TNF)-α, interleukin (IL)-6 and high mobility group box 1 (HMGB1) concentrations in a 48-h model of canine endotoxemia by lipopolysaccharide (LPS) injection. Four healthy beagles were slowly administered 1 mg/kg of LPS diluted in normal saline, while two others were administered normal saline as controls. Blood collection was performed at 0 h (baseline), 1 h and 3 h (for TNF-α), 6 h, 12 h, 24 h and 48 h of the experiment, and cytokine levels were determined using the sandwich ELISA method. Early increments of TNF-α and IL-6 were observed (less than 3 h), but HMGB1 levels increased the most at 12 h of the experiment and gradually decreased until 48 h. During the whole experiment, IL-6 and HMGB1 were sustained over 12 h of LPS injection, whereas TNF-α decreased within 6 h of LPS injection. Taken together, canine HMGB1 levels increase relatively late (less than 12 h) and sustained longer than TNF-α and IL-6 in response to endotoxin. This is the first study to evaluate canine HMGB1 cytokine from endotoxemia in dogs.

This study evaluated the analgesia effects of the epidural administration of 0.1 mg/kg bodyweight (BW) of morphine or 5 micrograms/kg BW of buprenorphine in ponies with radiocarpal joint synovitis. Six ponies were submitted to 3 epidural treatments: the control group (C) received 0.15 mL/kg BW of a 0.9% sodium chloride (NaCl) solution; group M was administered 0.1 mg/kg BW of morphine; and group B was administered 5 micrograms/kg BW of buprenorphine, both diluted in 0.9% NaCl to a total volume of 0.15 mL/kg BW administered epidurally at 10 s/mL. The synovitis model was induced by injecting 0.5 ng of lipopolysaccharide (LPS) in the left or right radiocarpal joint. An epidural catheter was later introduced in the lumbosacral space and advanced up to the thoracolumbar level. The treatment started 6 h after synovitis induction. Lameness, maximum angle of carpal flexion, heart rate, systolic arterial pressure, respiratory rate, temperature, and intestinal motility were evaluated before LPS injection (baseline), 6 h after LPS injection (time 0), and 0.5, 1, 2, 4, 6, 8, 10, 12, 16, 20, and 24 h after treatments. Although the model of synovitis produced clear clinical signs of inflammation, the lameness scores in group C were different from the baseline for only up to 12 h. Both morphine and buprenorphine showed a reduction in the degree of lameness starting at 0.5 and 6 h, respectively. Reduced intestinal motility was observed at 0.5 h in group M and at 0.5 to 1 h in group B. Epidural morphine was a more effective analgesic that lasted for more than 12 h and without side effects. It was concluded that morphine would be a valuable analgesic option to alleviate joint pain in the thoracic limbs in ponies.

Objective: To determine the effectiveness of preinduction hyperbaric oxygen treatment (HBOT) in ameliorating signs of experimentally induced endotoxemia in horses. Animals: 18 healthy adult horses. Procedures: Horses were randomly assigned to 1 of 3 equal-sized treatment groups to receive normobaric ambient air and lipopolysaccharide (LPS), HBOT and LPS, or HBOT and physiologic saline (0.9% NaCl) solution. Horses were physically examined, and blood was obtained for a CBC and to determine concentration or activity of plasma tissue necrosis factor-α, blood lactate, and blood glucose before the horses were treated with HBOT and then intermittently for 6 hours after administration of LPS or physiologic saline solution. Results: All LPS-treated horses developed signs and biochemical and hematologic changes consistent with endotoxemia. Treatment with HBOT significantly ameliorated the effect of LPS on clinical endotoxemia score but did not significantly improve other abnormalities associated with endotoxemia. Conclusions and Clinical Relevance: The protective effect of HBOT was minimal, and results did not support its use as a treatment for horses prior to development of endotoxemia.

Objective—To evaluate effects of black walnut extract (BWE) on equine mononuclear cells and determine whether BWE has direct proinflammatory effects. Sample—Mononuclear cells separated from blood samples from 8 horses. Procedures—Aqueous BWE was prepared and processed to eliminate contamination with particulates and microbes. A Limulus amoebocyte lysate assay was used to detect lipopolysaccharide (LPS) contamination in the BWE. Mononuclear cells were incubated in minimal essential medium with or without the addition of 0.6% to 10% (vol/vol) BWE. These mononuclear cells were assessed for viability, activities of caspases 3 and 7, nitric oxide production, procoagulant activity, and tumor necrosis factor-α production. The effect of LPS on cellular responses induced by BWE was assessed by coincubation with 13 U of polymyxin B/mL; mononuclear cells incubated with LPS were used as a reference. Results—BWE did not cause loss of cell membrane integrity in mononuclear cells but did induce a dose-dependent increase in activities of caspases 3 and 7. Neither BWE nor LPS significantly induced production of nitric oxide. Both BWE and LPS induced comparable amounts of procoagulant activity and tumor necrosis factor-α production; coincubation with polymyxin B reduced the activity for BWE and LPS by 50% and approximately 100%, respectively. Conclusions and Clinical Relevance—Addition of BWE induced inflammatory activation of equine mononuclear cells, a portion of which was independent of the effects of LPS. Furthermore, BWE and LPS may work in concert to induce systemic inflammatory responses that contribute to the development of acute laminitis in horses.

Objective—To examine behavioral and physiologic effects of lipopolysaccharide (LPS)-induced mastitis in lactating dairy cows. Animals—20 Holstein cows. Procedures—Cows were assigned to 5 blocks (4 cows/block) on the basis of parity and number of days in lactation. Intramammary infusion and IV treatments were assigned in a 2 × 2 factorial arrangement. Cows within each block were assigned to receive intramammary infusion with 25 μg of LPS or sterile PBS solution 3 hours after milking, and treatment with flunixin meglumine or sterile PBS solution was administered IV 4 hours after intramammary infusion. Video monitoring was continuously performed during the study. Results—LPS-infused cows spent less time during the first 12 hours after infusion lying, eating, and chewing cud, compared with results for PBS solution-infused cows. Behavioral responses were correlated with physiologic responses for the first 12 hours after intramammary infusion. Flunixin meglumine administration after intramammary infusion mitigated some behavioral and clinical systemic responses. Conclusions and Clinical Relevance—Intramammary infusion of LPS caused changes in both behavioral and physiologic variables in lactating dairy cows. Time spent lying, eating, and chewing cud were negatively correlated with physiologic responses in cows. Evaluation of behavior patterns may provide an ancillary measure, along with evaluation of physiologic variables, for monitoring well-being, clinical responses, and recovery from acute clinical mastitis.