Probably antibiotics to be used when he sews up cuts and gashes on his cattle or dogs.......I think the nearest town big enough to have a vet was about 55 miles away so that's why they do most of the minor stuff themselves.
And YOU would be RIGHT! Most farmers(at least the “Old-School” ones that I grew up with) are almost like Vets w/out the “Degree”. About the ONLY time my Dad and Farmers like my Dad would call/or visit the Vet’s Office or have the vet come to the farm was in the event of DIRE Emergency. Most Older Farmers have a Vet they like and they stick with that one for YEARS!