I would almost bet my weekly paycheck that he has a sinus cyst. And yes it is scary that a rescue does not realize a brain tumor would never be seen.( do they KNOW where the horse brain sits??)  I just went through this with my mare. Some times a cyst will not be visible from the outside, yet they will have nasal discharge that may include blood, and difficulty breathing.But a lot of times a lump shows up. My mare had a bump show up right along the bone that is below the eye.Long story short,  Thought she had a normal sinus cyst..but it wasn't..ended up trying to biopsy..took her for a CT scan and saw how big this thing was, did surgery and then found out it was a fibro sarcoma. ( rare in horses) She seems fine now, two months post surgery. But cancer is cancer.

A 'normal' sinus cyst can easily be removed .It is done as a standing surgery, a piece of the bone has to be broken once the sinus cavity is cut into, and then the cyst can pretty much just be pulled out. It will on occasion grow back. If you go to you tube and look for horse sinus surgery , and you are not at all queasy, there is video of it. ( My mare was a little different as the tumor had already eaten away bone and involved here teeth and..well just say if the original biopsy had come back as cancer she would be over the rainbow bridge now)

I know how hard it is not having control over the situation. Hugs

Sheri in PA

2006/2007