Have you considered Tritrichomonas Foetus? It has to have special tests done at a lab that tests for it, usually NCSU. The stool also needs special collection and handling. If your Vet is not familiar with it there are all the links to the most up to date info on the heatlh site here under Tritrichomonas. It is more common than a lot of people or vets think and most vets have not yet gotten much training on it. I have been dealing with it for over two years so I have quite a bit of info and knowledge on it. We have worked with all the experts on this issue. If you want to PM me I can try to help. In the mean time I will go into the health section and bump it back to the top so you can find it. We tryed everything under the sun before finally testing for this, I wish with all my heart it had been done sooner. Good luck. Dianne