Specifically, they make Vinca alkaloid chemotherapy from the Vinca plant. Just because something is natural does not mean it is without risk of causing harm. The dose for vincristine for a 30kg dog with lymphoma (a vincristine-responsive disease) for example is a little over a half of one thousandth of a gram. At this dose, the likelihood of benefit (destroying more than half the cancer) is around 75% and the risk of any side effects around 10%. Any more is likely to cause illness, any less is unlikely to work. When the extract is prepared in a controlled laboratory environment it is straightforward to dose with this much accuracy. Frodo's poisoning was tragic and although he never received a Vinca alkaloid in his treatment it re-enforces how the difference between helpful and harmful is often a matter of dose.
_________________ _______________ Dr Ken Wyatt BSc BVMS FANZCVS Specialist Veterinary Oncologist Perth Veterinary Oncology
|