The Rise of At-Home Care Between Vet Visits
Owners are doing more themselves in the gaps between professional appointments. That is mostly good, and it has one predictable failure mode.

There has been a steady shift in what owners handle themselves. Not treatment, and not diagnosis, but the maintenance layer that sits underneath both: monitoring, routine care, and the general business of noticing.
Several things pushed it. Professional time is expensive and often needs booking ahead. Information that used to be difficult to find is now easy to find, with all the benefits and hazards that implies. And a generation of owners has arrived who are comfortable researching before phoning.
What owners have genuinely taken on
The useful end of this is the monitoring layer.
Owners keeping baseline vital signs so they can describe a change rather than a feeling. Owners filming a gait so a professional sees the horse on a bad day rather than on the day of the appointment. Owners tracking weight, condition, water intake and droppings systematically enough to spot a trend.
None of that competes with a vet. It makes the vet's job considerably easier, because the professional arrives with a history instead of a snapshot. A horse that is intermittently lame is a genuinely hard problem, and an owner with three weeks of notes and a video has changed what is possible in that appointment.
The best version of at home care is not treatment. It is better observation handed to somebody qualified to interpret it.
The failure mode
The predictable hazard is substitution rather than support.
It looks like this. Something is not right. The owner researches, finds a plausible explanation, and starts managing it. The management produces partial improvement, because a lot of interventions produce partial improvement in a lot of conditions. Weeks pass. The underlying problem, whatever it actually was, has not been examined.
The specific danger is that partial improvement is convincing. A horse that seems a bit better is much harder to escalate than a horse that is clearly worse, and the timeline quietly extends.
This is where the internet genuinely has made things riskier rather than easier. Finding a plausible explanation has become effortless, and plausible is not the same as correct.
The line that holds up
A workable rule is the difference between maintaining and treating.
Maintaining is what you do to a healthy horse to keep it that way, and to inform the people who look after it: grooming, monitoring, conditioning, routine care, record keeping.
Treating is what you do to an animal that has something wrong with it. That requires knowing what is wrong, and knowing what is wrong is a diagnostic act.
Owners who stay on the maintaining side of that line, and escalate promptly when they cross it, tend to get the benefits of both. Owners who drift across it without noticing are the ones who arrive at the vet later than they should have.
Where it is heading
The direction of travel seems clear enough. Owners will keep taking on more of the maintenance layer, and the tools available to them will keep improving.
The question that decides whether this is good or bad for horses is not the equipment. It is whether the culture around it keeps insisting on the difference between watching a horse carefully and deciding what is wrong with it.