A retrospective study of vein thrombosis in horses treated with intravenous fluids in a veterinary teaching hospital.

The medical records of 68 horses treated with IV fluids for 24 hours or more were reviewed to determine the risk of vein thrombosis and to determine which factors were associated with the occurrence of vein thrombosis in these horses. Three factors were positively associated with vein thrombosis including use of locally produced fluids and presence of fever and diarrhea. Two factors, having general anesthesia or having surgery, were negatively associated with vein thrombosis. One continuous variable, duration of treatment, was positively associated with vein thrombosis. Factors not associated with vein thrombosis included breed, age, sex, type of catheter, outcome (lived or died), laminitis, colic, other drugs via the catheter, and type of surgery. One type of catheter was used in the majority of horses (57) making it difficult to detect effect of catheter type. Preparation of the catheter site, the person placing the catheter, and technique of catheter maintenance were not evaluated. Like all retrospective studies, this study has limitations to the conclusions that can be made; however, the strong association between source of fluids, fever, diarrhea, anesthesia/surgery, and the occurrence of vein thrombosis merits consideration in the clinician's therapeutic plan.