Hi Amanda! There are several reasons why he may not be "clotting" post op. Certain meds can have a blood thinning effect, and Smokey may have a preexisting condition that might predispose him to a longer clotting time, which may be rooted in a host of causes. With humans, we test their clotting time pre op to prepare for potential problems but this is rarely done, I'm told, with animals. With humans, we treat with injectable Aquamephyton, Vitamin K, which helps to clot the blood. It sounds like your vet is dong the proper blood work, PT, PTT, to determine his ability to clot and will treat the condition with medication. That is assuming that he's excluded other reasons such as a "bleeder," or vein that needs to be tied off, or suture line that has opened up. Has Smokey been on any aspirin lately for pain? I wondered as he had knee surgery and was probably in some discomfort pre op. Aspirin has definite blood thinning qualities. Oh, I do hope your sweet Smokey will be ok. It sounds like your vet has a handle on things Please check back when you hear more! Hugs to Smokey...get well soon