When making choices wrt antibiotic selection, one needs to consider risk vs. benefit.
In most cases, there isn't a significant advantage to procaine penicillin G over either oral trimethoprim/sulfa or other injectable antibiotics ( ex. ceftiofur) that are less likely to result in an adverse reaction than is PPG, which is why its use has diminished greatly.
"It's like a Russian nesting doll of train wrecks."--CaitlinandTheBay