A lot of people who used horse-powered travel in the late 19th century used carriages and the like. Taxis with horses were pretty common. So a direct comparison to the dangers of horseback riding may be not called for. On the other hand, horses also created a highly unsanitary environment due to horse excrement and urine. I don’t know how much that impacted disease substantially. I’d expect it not to have that large an impact, but I’m not sure even what the first steps would be in making an estimate for that.
Another way to look at it: are they more dangerous than horseback riding?
A lot of people who used horse-powered travel in the late 19th century used carriages and the like. Taxis with horses were pretty common. So a direct comparison to the dangers of horseback riding may be not called for. On the other hand, horses also created a highly unsanitary environment due to horse excrement and urine. I don’t know how much that impacted disease substantially. I’d expect it not to have that large an impact, but I’m not sure even what the first steps would be in making an estimate for that.
Correlating recorded disease rates with recorded horses per capita would be a place to start, though of course there are many confounding factors.
Probably. On the other hand, it’d be quite impractical for most people in a several-million-inhabitant city to have a horse.