Pentoxifilyn (Trental) is used in humans to treat peripheral artery disease because it acts as a 'blood thinner', that is it decreases the viscosity of blood. After doing a quick Internet search it looks like it has been used in dogs to treat dermatitis, but I don't think that is Mungus' problem (although it may be of benefit for his HCM as it could decrease his chances of forming blood clots that can occur because the heart isn't pumping as efficiently as it should).
Did the doc tell you why she suspects FIP? What were the biopsy results?
Here is the Cytology report - they said it was NOT cancer - other than that they just said POSSIBLE FIP
Pathological Findings – Cytology
Diagnosis
Pancreas: Moderate, mixed inflammation with low-grade chronic active hemorrhage, see comment
Spleen: Moderate pyogranulomatous inflammation with necrosis
Comments
Although a well differentiated pancreatic carcinoma cannot be definitively ruled out, it is not suspected; rather, epithelial reactivity and or hyperplasia is suspected. Also present in the liver and spleen is an abundant amount of mixed to pyogranulomatous inflammation.
Although this inflammatory infiltrate is somewhat nonspecific, this infiltrate with the history of hyperglobulinemia of 9.0 g/dL warrants a suspicion of FIP. Upon request, slides can be sent to Auburn University for coronavirus PCR (although this test will still not give definitive results). Biopsy/histopathology may also help confirm/ruleout this differential.
Microscopic Description
Pancreas: The slides from the pancreas of Mungus are moderately to highly cellular and consist of a relatively small amount of peripheral blood, a lightly proteinaceous background, and a heterogeneous nucleated cell population that consist of numerous small clusters of pancreatic epithelial cells, surrounded by numerous macrophages, neutrophils, and occasional eosinophils. These pancreatic epithelial cells appear fairly uniform, however these clusters are mildly disorganized with a mildly increased nuclear density. Anisokaryosis is minimal; nuclear chromatin is densely clumped with rare visible nucleoli. Macrophages occasionally contain intact red blood cells and a small to moderate amount of globular material suggestive of hemosiderin. No microorganisms found after thorough search.
Spleen: The slides from the spleen are lightly to highly cellular and consist of a large amount of cellular debris consistent with necrosis with occasional aggregates of splenic stroma surrounded by numerous poorly preserved neutrophils, macrophages, with fewer small mature lymphocytes and plasma cells. No microorganisms found. Leukophagocytosis is occasionally noted.