Transient weakness, ataxia, and recumbency associated with catheterizationof the right side of the heart in three horses

Right-sided cardiac catheterization for measuring cardiac output via thermo dilution is a standard method for assessing cardiovascular/hemodynamic func tion in horses. Clinical complications related to right-sided cardiac cathe terization in this report include weakness, ataxia, collapse and a concomit ant rise in pulmonary artery pressure; clinical signs resolved in two to 24 hours. Differential diagnoses for the clinical signs in the horses of this report include air embolism, stimulation of mechano receptors in the pulmo nary artery (vasospasm/vaso constriction), thromboembolism, stress, and sep sis or endotoxemia.. Awareness of the potential risks of cardiac catheteriz ation in horses may help researchers and clinicians to prevent or minimize some of the more serious complications inherent to the procedure.