I am a firm believer in the old cowboy adage, “If it ain't broke, don't fix it!” Nature illustrates the wisdom of this claim when it teaches us that the overwhelming majority of genetic mutations are deleterious. For this reason, I tend to be conservative about making precipitous and major decisions in my life, such as retirement or a job change, as it seems to me that things are likelier to get worse, rather than better.
This principle, in my view, applies very clearly to this case. Presumably, the current regimen works well for both veterinarian and client. The only advantage to making a change would be a brief, pecuniary one. The veterinarian could either pass the saving on to the client or keep it. If the veterinarian keeps it and the client finds out, for example, by asking why the veterinarian changed regimens, the client will doubtless be annoyed. If the veterinarian passes it on to the client, the client will be annoyed when the price goes up again. Further, every veterinarian knows that clients, particularly in the food animal area, tend to resent spending what they do on veterinary services and medicaments, particularly on preventative rather than curative modalities. A good practitioner will have “trained” the client not to begrudge what is spent on preventative medicine. Dropping the established regimen to save a few dollars is likely to reopen the old wound and have the client worrying again about excess profits accruing to pharmaceutical companies and wondering why, if you can get a break on the product once, if you can't get such a break all the time! In short, the only good that can come out of making the change is some very short-term savings. On the other hand, the problems that can arise from the change are far more numerous, ranging from diminution in efficacy to reopening the client's silent concerns about costs. From a strictly cost and benefit perspective, then, the possible costs outweigh the possible benefits, and I would not make the change.