Horses do not usually catch Salmonella directly from other horses. It is primarily a foodborne illness.
Horses most often get Salmonella by ingesting contaminated feed, hay, or water, or by contacting contaminated surfaces. Bacteria can also spread through manure, though direct horse-to-horse contact is less common.
Once ingested, Salmonella multiplies in the gut and causes illness. To reduce risk, keep feeders and buckets clean, manage manure properly, and isolate sick horses. Contact your veterinarian if you suspect Salmonella.