A reputable scientific journal suggests that a common, natural, no-calorie coffee sweetener may be a potential cure for Lyme disease:
In this study, we evaluated the effectiveness of whole leaf Stevia extract against B. burgdorferi spirochetes, persisters, and biofilm forms in vitro. The susceptibility of the different forms was evaluated by various quantitative techniques in addition to different microscopy methods. The effectiveness of Stevia was compared to doxycycline, cefoperazone, daptomycin, and their combinations. Our results demonstrated that Stevia had significant effect in eliminating B. burgdorferi spirochetes and persisters. Subculture experiments with Stevia and antibiotics treated cells were established for 7 and 14 days yielding, no and 10% viable cells, respectively compared to the above-mentioned antibiotics and antibiotic combination. When Stevia and the three antibiotics were tested against attached biofilms, Stevia significantly reduced B. burgdorferi forms. Results from this study suggest that a natural product such as Stevia leaf extract could be considered as an effective agent against B. burgdorfer.
But wait. Before you start dumping Stevia packets you have lifted from Starbucks into your dog's food, be aware that Stevia does NOT cure Lyme.
For one thing, those Starbucks Stevia packets are a highly refined product, and what you will be wanting is whole leaf Stevia, preferably stalks from plants you have grown in your own garden and not stuff imported from China.
Even then it will not work.
Read the indented paragraph above very carefully. Do you see the words IN VITRO? That means this stuff only works in a test tube or petri dish.
Why won't it work in your dog (or you)?
Simple: to treat Lyme disease, the chemical compounds in Stevia must be absorbed through the intestines, but Stevia is mostly NOT absorbed in the intestines, which is why it works so well as a sweetener.
In short, the Stevia story is interesting and may yield a new product in time, but for now the best way to treat a dog with Lyme is with antibiotics.
For more information on that, see here and here and here and here. These links advise using doxycline to treat Lyme, but the same results can be achieved with amoxicillin at 10 mg per pound of dog, dosed twice a day.