As a horse owner, you are the person most responsible for the health and welfare of your horse and its daily care, and this includes care of the feet. Perhaps you do your own trimming (and a few owners also do their own shoeing), or like most owners hire a professional farrier to come periodically to trim or shoe.
Even though your farrier may come to trim/shoe every 5 to 8 weeks or so - the frequency depending on your horse's specific needs and how quickly his feet grow, and whether he is being reshod or just trimmed - the horse depends on you to monitor and care for his feet in between farrier visits.
Keeping track of hoof health and growth helps prevent problems and also alerts you when the farrier needs to see the horse sooner than the next scheduled visit.
The horse's hoof wall grows about one-quarter to three-eighths inch per month, growing down from the horn-producing cells at the coronary band. The entire hoof wall is usually replaced by new horn every eight to twelve months (and by that time all the old horn, including defects and cracks, will be replaced), though some horses have a slower or faster rate of hoof growth.
If a horse is shod, the shoes prevent any wear on the feet. They may need to be reset (if they are not too badly worn) or replaced with new shoes (after proper hoof trimming) every four to fourteen weeks, with six to ten weeks being average--depending on rate of hoof growth and whether the feet are properly balanced at the time of trimming/shoeing.
If a horse's feet grow fast and the foot is out of balance, the toes may become too long in just three to four weeks after trimming/shoeing, with more risk for stumbling. Other individuals can easily go two months or longer (especially if the feet are balanced and the horse has good conformation and isn't prone to tripping or stumbling) before needing to be reshod - unless the shoes wear out faster or come loose.
Keep in mind, however, that if the feet are allowed to grow too long the hoof wall may start to grow down around the shoe at the heels, putting pressure on the sole at the bars, which might lead to corns or bruising.
There will also be more strain on joints and the support structures such as tendons or ligaments. If the horse is barefoot there will be more forces on the hoof wall (which could lead to splits and cracks, or stretching/opening at the white line).
In a too-long foot there is also more chance for hoof diseases like thrush or white line disease.
If shoes are left on too long they may become loose. Nails heads may wear off. A loose shoe can be a hazard if it slips out of place and the horse bangs himself with the shoe or protruding nails.
Always check the feet and clean them out on a regular basis, even if they don't need be trimmed or reshod yet, to make sure there are no problems developing.
Thrush is unmistakable grimy black secretions in the clefts of the frog, with a bad odor.
White line disease is more obscure, with pathogens entering at the white line if there is a bit of separation when the horse puts weight on the foot, especially a bare foot without a shoe to protect it. The horn-eating pathogens hollow out an ever-upward-extending area between the outer hoof wall and the inner tissues, and this hollow area may not be visible on casual inspection.
Under natural conditions in big pastures with varied terrain and footing (such as horses running free on rangelands) bare feet wear down about the same rate they grow; hoof growth compensates for wear and the feet stay about the proper length without the need for trimming.
If a horse is being ridden however, traveling more miles, the bare feet may wear faster than they grow and the horse will need shoes.
The trimming intervals for a barefoot horse kept in a smaller pasture or pen, or in a stall with limited turnout, may vary greatly, depending on whether the horse is on soft footing that doesn't wear away the hoof horn, or abrasive footing like gravel or rocky ground.
A horse on soft ground or wet pasture may need frequent trimming because there is very little wear to remove the natural hoof growth. How much you ride the horse will make a difference.
A barefoot horse being ridden frequently or traveling around in a rocky pasture may have so much wear that the feet won't need to be trimmed at all, except to occasionally smooth the bottom edges to keep them from breaking and chipping. This is something you can usually do yourself, if you have a good rasp.
Keeping the edges smooth will help prevent breaking or cracking. If the edge gets chipped or a crack starts, frequent smoothing can help prevent further breaking or keep a crack from continuing on up the hoof wall.
If the horse is ridden very much on hard ground or gravel roads or pavement he will wear the feet faster than they can grow and he may need shoes after just a few rides. Some horses have harder, tougher feet than others and can go a long time without shoes, while other horses tend to break/chip their hoof walls or stone bruise if you ride them on rocky ground.;
Many horses are better off wearing shoes if you ride them, only going barefoot during layoffs or during wintertime when you aren't riding.
With flat-footed horses or those with fragile hoof horn, it's usually best to shoe them before you start riding again in the spring, to keep them from becoming tender or lame.
You and your farrier can determine the appropriate schedule and timing for trimming and shoeing your horses. The biggest challenge is getting the timing right if you have multiple horses with different rates of hoof growth.
It's handiest for your farrier to do them all at the same time, on a certain schedule, but this may mean one horse's feet grow too long between farrier visits or another horse isn't quite ready yet for the next trimming/shoeing because his feet haven't grown very much since the last trimming/shoeing.
These are things you and your farrier must work out and it may mean more frequent farrier visits to time the foot work most appropriately for each horse.