What can cause blood clots?

Bird Experts: What would cause a baby swan not to grow very much, then lose blood clots and die :(?

• I rescued a baby swan whose mother had abandoned it. I am assuming that the mother knew something was wrong and thats why she let him go. Anyways, he was at least a few months old when we found him. He was eating normal food, and he quickly became really tame. He was my little buddy, he would say "peep peep" and wait for me to call back and say "here I am" then he would either come running if I was close enough or he would continue calling for me until I ran over and scooped him up to take him with me. He was totally attached to my side. One thing was obvious though, after several months he had not grown as fast as babies normally do. He was probably half size of what he was supposed to be at about 4 months+. Anyways, his last day came one sad day, I filled up the bathtub for him to take a swim (he loooooved it) and while he was in the bath, I noticed he pooped out a blood clot, then he ate it out of the water. It happened really fast but I was sure of what I saw. Then after he got out of the bath, his head began to sway back and forth, a little at first then it got really bad where he could not hold his head up at all. It was the saddest thing ever. Eventually a few minutes later he just died. What do you think was wrong with him? Does this explain anything? It happened a while ago now but it still really bothers me and I want to know what happened. Also he was a huge lesson to me as well as anyone else, swans are not mean birds, they are a product of their environment. This swan was affectionate and cuddly, and it loveeed people.

• Answer:

  sounds like swan was infected with parasites or worms