The medical exemption clause in SB 566 was removed from the version of the bill which passed on 5/17/12. The "Truly Agreed To and Finally Passed" version of SB 566 which did pass http://www.senate.mo.gov/12info/pdf-bill/tat/SB566.pdf
was not posted on the Legislature's website until a week after passage, leading to the incorrect conclusion that the "Perfected" bill text appearing on the Legislature's bill status including waivers http://www.senate.mo.gov/12info/pdf-bill/perf/SB566.pdf
had passed. This version of the bill including rabies waivers did not, in fact, pass.
According to the Missouri Department of Agriculture's Legislative Liason, Rachel Mobley, the final version of SB 566 stripped the language which required all dogs and cats to be vaccinated against rabies. Because there is no statutory requirement for rabies vaccination in the final bill or in state law, there was no need for a medical exemption clause in SB 566. Rabies vaccination requirements are determined at the county level.