Imaging diagnosis--Arterial and venous thromboses of the proximal limb in two thoroughbred racehorses.

Thromboses of the cranial tibial vein (Horse 1) and brachial, median, and cranial circumflex humeral arteries (Horse 2) were identified as causes of unilateral lameness in two Thoroughbred racehorses. Nuclear scintigraphy was performed for suspicion of long bone stress fractures but instead allowed identification of unusual areas of increased radiopharmaceutical uptake within soft tissues of the affected limbs. Ultrasonography of these regions allowed identification of occlusive thrombi within a 25 cm length of the cranial tibial vein (Horse 1) and variable lengths of affected arteries in Horse 2. Horse 1 developed secondary infections and was euthanized. Staphylococcus aureus was isolated from all sites. The cause of thrombosis was not identified in Horse 2.

Effects of intravenous administration of pirfenidone on horses with experimentally induced endotoxemia.

OBJECTIVE: To characterize effects of IV administration of pirfenidone on clinical, biochemical, and hematologic variables and circulating tumor necrosis factor (TNF)-alpha concentrations in horses after infusion of a low dose of endotoxin. ANIMALS: 18 healthy adult horses. PROCEDURES: Horses were randomly assigned to 3 groups (n = 6 horses/group) and administered an IV infusion of 30 ng of endotoxin/kg or saline (0.9% NaCl) solution during a 30-minute period. Lipopolysaccharide-pirfenidone horses received endotoxin followed by pirfenidone (loading dose of 11.6 mg/kg and then constant rate infusion [CRI] at 9.9 mg/kg/h for 3 hours). Lipopolysaccharide-saline horses received endotoxin followed by infusion (loading dose and CRI for 3 hours) of saline solution. Saline-pirfenidone horses received saline solution followed by pirfenidone (loading dose and then CRI for 3 hours). Physical examination variables were recorded and blood samples collected at predetermined intervals throughout the 24-hour study period. Blood samples were used for CBCs, biochemical analyses, and determinations of TNF-alpha concentrations. RESULTS: IV infusion of pirfenidone after administration of a low dose of endotoxin failed to attenuate the clinical, clinicopathologic, or cytokine alterations that developed secondary to endotoxin exposure. Intravenous infusion of pirfenidone after administration of saline solution induced mild transient clinical signs, but associated clinicopathologic changes were not detected. CONCLUSIONS AND CLINICAL RELEVANCE: IV administration of pirfenidone was tolerated with only mild transient clinical adverse effects during infusion. However, administration of pirfenidone did not protect horses from the systemic effects of experimentally induced endotoxemia. Further studies of related, but more potent, drugs may be warranted.