Hi Heather,
Both Voltrex and Cessorex contain Minor Bupleurum at their core. Minor Bupleurum is effective against multiple types of latent infection including Lyme disease and Anaplasmosis. I will be lecturing on the science of why Minor Bupleurum is so effective for these infections at the Southwest Veterinary Symposium in San Antonio this September, if you're in the area.
Of these two formulas, I might reach most commonly for Cessorex when I'm treating Anaplasmosis if there is associated bone marrow suppression and anemia. I might reach for Voltrex for Lyme disease because it also addresses joint pain and inflammation very well. Apart from that, though, they are somewhat interchangeable because of their shared Minor Bupleurum core.
In terms of duration of treatment, I would use the same criteria that you might use if treating these infections conventionally. For Anaplasmosis, assuming you're finding the formula effective, I would discontinue treatment only once signs and symptoms have abated. I would then wean gradually, seeking the lowest required dose to maintain that symptom-free state. Usually, you will be able to discontinue the formula.
For Voltrex, we'd want to see symptoms resolve and then seek the lowest required dose. The quantitative C6 titer should be tracking downwards during that improvement. Certainly, once the C6 is below (I think it is) 16, you shouldn't need the Voltrex anymore, if symptoms have also resolved.
Latent pathogens are very gratifying to treat with herbal medicine, so hopefully this all makes enough sense for you to take a stab at treating those patients yourself. If you opt for doxycycline, the drug is compatible with these formulas, but many veterinarians find the formulas themselves suffice
Steve