The only real practical challenges to using well fitting hoof boots day to day are the issues concerning putting them on or maintaining them
For example, cold fingers in winter, boots that haven’t dried out from a muddy ride, or simply getting the knack of fitting them, which we all quickly achieve, after a few tries!
However where competitive events are concerned, there are challenges:
In the UK, you may use hoof boots for horse trials and the jumping phases of eventing, bearing in mind your speed and safety - you may also use them in TREC and endurance events.
However, you may not use hoof boots within the dressage phase of affiliated eventing, or within pure dressage competitions.
Furthermore, hoof boots aren’t allowed in affiliated dressage, although as most classes are on a surface, most dressage fans with barefoot horses would not find this an issue - if you have a horse that requires hoof boot protection on an arena surface due to discomfort, it would be wise to discuss the horse’s hoofcare regime with your hoofcare professional before continuing to compete.
While hoof boots would technically be allowed in unaffiliated dressage, some judges may take a dim view of them as the rider moves up the levels, as they could be seen to affect the animal’s action. However, if you have hacked to an unaffiliated venue to contest a low-level dressage competition and will be hacking home, it is unlikely that the judges will mind your hoof boots. It makes sense in this situation to chat to the judge or steward, and explain that you’d like to keep your hoof boots on. Furthermore, if your horse is recently transitioning, the types of arenas with hard, large lumps of rubber could cause discomfort, and hoof boots would aid his comfort. Similarly, you may want to use hoof boots prevent sand from a manege getting into a recovering deep central sulcus infection, or other sore area of the foot, and again a quick explanatory word with the steward would be fine.
For affiliated dressage competitions, in terms of the rules, it would be fine to warm up in your hoof boots and remove them just before you went into the ring - this could be beneficial if, for example, the car park at the venue is very pebbly (some venues are said to have undesirable surfaces to discourage owners from letting their horses defecate there!). There could even be a potential theory that warming up in boots and then removing them would allow the horse to really beneficially express his paces once in the dressage test.
Showing
Showing is traditionalist, hence hoof boots would be frowned upon. Even going barefoot without hoof boots is fraught with controversy, with barefoot horses being banned entirely from the show ring in working hunter and some other classes (in the UK).
So, to summarise, equestrianism’s governing bodies do enforce rules that can provide challenges to competing in hoof boots at the higher level events.
