Sunny asked if I would talk more about how I check digital pulses in my horses - how I do it, how often and what I make of what I find. First, a caveat - I am not a vet, and this is just my best layperson's description of what I do and what I believe it means. Everything in this post is based on my own research, practice and opinions. And since we're talking about digital pulses, I'll bring up some of the hoof health issues that are raised - digital pulses are (to use an odd metaphor) just the tip of the iceberg . . .
First, where and what are the digitial pulses (or lack of digital pulses)? Here are two links that explain what they are and where to find them. I like the detail in the first link (which includes some cadaver dissections that show the structures of the horse's legs), and in the second link, the illustration is how I check for digital pulses - I place my hand over the front of the fetlock and place my thumb (on one side) and two fingers (on the other side) just below the sesamoid bones and behind the suspensory ligament ligaments - as in the picture in link 2. I don't usually check digital pulses every day, although I do check them every day during introduction of a horse to grass pasture or any other significant dietary change. (But then again, it's so easy to check them in just a second or two, I may just make it a regular part of my grooming routine.)
Checking digital pulses: Link 1 and Link 2.
I believe that there are lots, and lots, and lots of horses out there with low-grade chronic inflammation in their feet that isn't so severe that their owners have noticed. And a lot of this low-grade inflammation leads horses to carry themselves incorrectly, resulting in low-grade or even more dramatic lamenesses. A lot of low-grade inflammation is also concealed by shoes and pads - it isn't necessarily better, just made less visible since the horse can appear sound. You don't get to full-blown inflammation - acute laminitis - without having less severe inflammation first. (A side note on terminology - I am using the term "laminitis" to refer to any inflammation in the hoof. The term "founder" should be used for laminitis that has progressed to rotation of the coffin bone. Horses can have varying degrees of laminitis without foundering, but founder cannot occur without laminitis.) All three of my horses have no detectable digital pulse in any of their four feet - and check all four, not just the fronts - when things are OK. With my horses, particularly with Pie who has had an episode of laminitis, progression from no pulse to a detectable pulse, even a small one, is a red flag. Some authorities say some digital pulse, although not a "bounding" one, is OK - I'm not so sure about that. Many horses can have a slight digital pulse and still be apparently sound, but that doesn't necessarily mean things are OK - things may be on the way to not OK, or there may be chronic low-grade inflammation. As with all horse health issues and vital signs, knowing your own horse's normal is very important.
Also, I believe that hoof health - soundness on a variety of surfaces, and good shape, working structure and the absence of abnormalities like abscesses - is primarily due to a combination of nutrition, exercise with a bit of genetics thrown in. Frequent abscesses are a sign that something isn't right, and it often isn't really about concussion or bruising, it's about total hoof health, and the related metabolic issues that are reflected in hoof health.
A few comments on those thoughts. I am far from a barefoot fanatic - although all three of my horses are barefoot - and shoes and/or boots may be required for certain horses in certain working conditions and boots may be required as a horse that is shod transitions to barefoot - no horse should ever be made to be uncomfortable or forced to work on surfaces where the horse is uncomfortable in the service of barefoot - despite what some schools of barefoot trimming may say. I do believe that horses didn't evolve to wear shoes, and that a healthy hoof only develops when it can work, particularly when it can work in the heel and sole areas. Also, healthy hooves grow from the top, they don't get produced by trims from the bottom, although a good trim can help (to a fairly minor degree) and a bad trim can certainly cause problems. A red flag for me is if your horse is barefoot and is sore after a trim - this means your trimmer is doing something wrong - likely being too aggressive with the trim. A lot of poor quality hooves - poor shape, poor hoof material, thin soles, propensity to abscesses - are actually caused by the hoof not being able to load, and thus develop, properly. Horse's hooves are dymanic structures, and are growing and changing every day. Here is a video (using a cadaver hoof) showing the way the horse's unshod hoof flexes under loading, and the way the internal structures move to support this.
There is a book that I've recommended before and continue to recommend - despite the title, it's really about hoof structure and function and what influences that - it's a very good resource whether your horse is barefoot or shod: Feet First: Barefoot Performance and Hoof Rehabilitation.
Exercise is critical to hoof health - and to the horse's metabolic health which is closely tied to hoof health. It is exercise, where the horse uses the various structures of its foot in the manner intended, that leads to the growth of healthy feet - but this takes time, a lot of time - in some cases until the entire hoof capsule has grown out. (If you want to see some interesting hoof transformations, visit the Rockley Farm blog - the same people who wrote the Feet First book cited above.) Exercise, together with nutrition, can contribute to a healthy weight and metabolism, which is necessary for healthy feet.
Nutrition is about what you feed your horse, but also about what you don't feed your horse. An obese horse isn't a healthy horse. A lot of people think their horses look just fine when in fact they're overweight or even heading for obese. Here is a very good article about scoring your horse's body weight. I pay more attention to the feel of the horse's body and the shape and size of various fat deposits than I do to the overall appearance of the horse. I'd like my horses to be in the range of 5 and never more than a low 6 in scoring. Dawn is currently a 4+ and needs a lot of supplemental calories just to stay there, Red is a 5 and needs some extra calories from time to time to maintain his weight and Pie is a 6+ (and he's always working hard at getting fatter!) and could probably live on air alone. I want my horses to be leaner not just because a less fat horse puts less strain on its legs and joints, it's also because an overweight horse will be more prone to metabolic issues that can lead to poor hoof health.
An appropriate level of vitamins and minerals can be very helpful, as can the appropriate ratios of omegas. Some horses may need thyroid supplementation. Forages should always come first, and concentrated feeds should be used with caution and feeds with high levels of sugars should be avoided. One of the biggest issues for our horses is profuse, rich grass pastures. Another big issue is the nutritional profile of many commercial horse feeds - many of them are too high in sugars (one measure of this is NSC levels) - and they're often fed as a matter of tradition and convenience for the horse (or barn) owner. Every horse owner should understand the nutritional content of what they are feeding their horse - and often some of the most important data isn't on the feed label - but you can find it if you do a little searching. Many horses who get supplemental grain really don't need it at all, and would be better off with a small amount of a low sugar grain or a vitamin/mineral supplement instead. But simply throwing supplements at your horse can be a waste of money - I believe a lot of supplements are at worse useless and at best unproven, and in certain cases supplementing can actually be harmful - if you supplement, make sure you know what your horse is getting from his total diet.
There is an excellent web site - safergrass.org - with lots of information on horses and grass. There is a lot to learn about grass - and much of what people think they know may be incorrect. Grass is dymanic, and the sugar content varies by type, time of day, weather, length of the grass and time of year. Some horses with metabolic issues cannot tolerate any grass, while others can if things are carefully managed - Pie is one of those. The plan for him at the moment is to keep him off the grass until July, when some of the lushness should have faded, and then slowly reintroduce him while keeping a very close eye on things. He is also now using a Busy Horse hay bag in both his stall and his paddock, to slow down his (otherwise prodigious) rate of eating.
That's a brief and oversimplified summary of a complicated topic - every horse owner should get out there and learn as much as they can about horse health issues, including those affecting the feet.