My horse is on a neighbor's land that is on loan. I pick up the pasture and run-in twice a day. My concern is that my neighbor bought over 100 different species of chickens and ducks that run free. They are constantly in my horse's shed, her pasture, and our backyard. Their feces are everywhere. He then purchased several goats and four sheep. The chickens wander into their pen too. I am concerned for the health of my family and horse. Do chickens and ducks pose a health risk to horses, humans, sheep, goats, and my dogs? Are there any vaccinations I should be pursuing for my animals in light of the chickens and ducks? Is Salmonella a risk?

I think you are at a disadvantage in that you're keeping a horse on land belonging to your neighbor. In light of that, in my opinion, you are not in a position to restrict the neighbor allowing his chickens and ducks free range on his land, even if your horse is pastured on it. However, I think you are entitled to request that the chickens, ducks, etc., do not have unrestricted access to the property you're using for your horse. It really is not within your purview to ask about the health hazards these birds might pose to the neighbor's sheep and goats.

To the best of my knowledge, the primary risk these birds might pose is as a source of Salmonella. While a wide range of Salmonella spp. can be carried by either chickens or ducks, the one I'd be most concerned about is S. enteritidis, which can be common in ducks. How significant a risk this is is impossible to say without some reliable indication of the Salmonella carrier rate in this flock. I'd suggest renewing negotiations with the neighbor to try and convince him of the need to maintain the offending species on his property.