Whether to vaccinate, and for what, are decisions that need to be made based on discussion with your vet on the prevalence of the diseases in your area; on the severity of the disease in question; as well as the likelihood your horses will come into contact with the disease. I know you know this.
In my area, the Fort Dodge (now Zoetis) vaccines have always been the ones most prone to eliciting reactions. I don't know if the formulations have changed since the merger of the companies. You can use banamine/bute to help prevent or lessen any negative responses but that will also blunt the entire immune response to some degree, so needs to be considered in the overall pros and cons.
To me, the biggest issue is that a 5 way vaccine is still inoculating for 5 diseases at once. This means the immune system is being asked to simultaneously ramp up protection for five separate diseases. Does this impact the quality of the response? Will it tip a sensitive horse over the edge?
The biggest pro to me is convenience: the savings in time and farm call fees stemming from multiple vet visits to administer the vaccinations separately.
Lavinia, George Too, Calvin (PPID) and Dinky (PPID/IR)
Nappi, George and Dante Over the Bridge
Jan 05, RI