A partial thromboplastin time (PTT) test measures the time it takes for a blood clot to form. Normally, when a cut or injury that causes bleeding, proteins in the blood called coagulation factors work together to form a blood clot. The clot stops the dog from losing too much blood.
There are several coagulation factors in blood. If any factors are missing or defective, it can take longer than normal for blood to clot. In some cases, this causes heavy, uncontrolled bleeding. A PTT test checks the function of specific coagulation factors.