autoimmune disorders, Infectious agents such as: Fungal diseases, Viral diseases, Bacterial diseases, Rickettsial, Protozoal , and Parasitic infections. There are many causative agents which include (but are not limited to): bartonella, toxoplasmosis, ehrlichiosis, babesiosis, anaplasmosis, leishmaniasis, and dirofilariasis (heart worm disease), and of course vaccine reactions as I have discussed above.