Aortic thromboembolism (ATE) is a life-threatening condition in cats. Many cats with this disease die or are euthanized due to poor prognosis. In people the “state of the art” treatment is catheter-directed thrombolysis whereby a catheter is introduced into the blocked artery and a medication that dissolves the thromb is injected directly into the blockage. This is the preferred treatment for people with ATE, and it has been suggested that this treatment is more effective with fewer side effects than other treatments. The aim of this study is to determine the clinical response, side effects and outcome of targeted intra-arterial administration of tissue plasminogen activator (a blockage dissolving drug) as a treatment of ATE in cats.