I don’t think the guy knows the difference. It’s kind of like the old farmer asking Dr Herriot, ‘Aren’t you going to give the horse an ‘injection’?’ as if injections are magically good, generic ‘things’ that cure everything.
And to others, all injections are generically ‘bad’.
That’s because they lack information. There is no science and no knowledge behind EITHER position.
There are joint injections given to keep older horses comfortable, in a light and appropriate level of work. Injections like hyaluronic acid improve the quality of the joint fluid and actually slow down the arthritic process.
There are also other joint injections - such as cortisone, given to keep a horse in an unreasonable level of work, without rest or rehabbing the injury, and these actually can erode the cartilage if given repeatedly and without resting the animal. Sometimes dozens of these are given over time, with the aim or concealing an increasingly severe arthritic process that the medication is actually worsening.
This was long a problem in horse racing and in various riding styles. I have pictures from vet journals of the kind of cartilage erosion that occurs when repeated cortisone injections are given without rehab and rest. It would make any reasonable person’s hair stand on end.
However, even cortisone injections can actually be beneficial for an injured animal, increasing the healing process. The problem is they are abused, the horse may be given cortisone repeatedly without rest, either to make sure he gets into a given competition, or to get him sold too some unsuspecting novice.
That medications are abused and misused (all medications have been misused by someone at some time in history) does not change what they do, or how they could be used.
For many people, all older horses should be out in a pasture. However, many older horses are actually far better off in light, reasonable work, not everyone has pasture, and not all pastures are actually all that suitable - rough rutted ground, especially when frozen or muddy, can be murder on certain arthritic processes. No one arrangement is right for all horse owners and all horses.
And comfort, actually, is something that people nowadays consider with horses - so that horses in light, reasonable work get anti inflammatory medication, hyaluronic acid injections, etc, without that being unethical, cruel or whatever.
There are even people who give injections of hyluron as a preventative to healthy horses. It isn’t yet clear to me that preventative injections of such things will really completely prevent or control an injury process from developing or progressing. I prefer to rely on careful conditioning, good footing, and good management.
There are also a growing number of therapies for equine injuries. Shock wave and a number of modalities can really help horses heal, when used with appropriate rehab.
Proper use of medications for therapeutic reasons is never wrong. That some people choose to abuse medications, does not mean that medications are wrong or bad.