Deep venous thrombosis is a disorder in which hazardous blood clots develop in the legs' blood veins. Dalteparin is used to avoid this. These blood clots may migrate to the lungs and lodge in the lungs' blood arteries, producing pulmonary embolism. This medication is also used in conjunction with aspirin to prevent blood clots from developing in the arteries of individuals suffering from unstable angina or a heart attack. Dalteparin is also prescribed for a period of time after abdominal surgery, hip replacement surgery, trap the cat or when you are unable to walk. Blood clots are more prone to develop during this period. Dalteparin is also used in children to treat symptomatic blood clots (such as pulmonary embolism or deep vein thrombosis) and in adults with cancer to treat symptomatic blood clots for a longer period of time.