Tucker and Marissa
I just read a wonderful blog post about the human-horse bond in scary or stressful situations. In her Sidelines Blog, Tucker the Wunderkind, my friend Marissa talks about the evils that can lurk under a docked rowboat and wonders who is making who more nervous. Is her horse simply wary of the unknown? As Tucker himself cleverly points out, “he is a 1200-pound, juicy, tasty, lean, flight animal, and he was therefore altogether NOT in the habit of nonchalantly approaching unidentified objects that could very well turn out to be sleeping predators just waiting for a mid-morning snack.” Or is his rider, who knows this horse so well, anticipating his reaction and contributing to the panic?
    If you read the full article, you’ll find out that a little bravery on both parts makes for a wonderful walk around the lake, but I’m a scientist, a number crunching, graph loving, p-value calculating researcher. I always want to know if there are cold hard facts to support the ideas we know to be truths. And that’s when I remembered the Umbrella Study and I wanted to share it with you, and all the Tucker fans out there. I think it does a great job of showing that it’s not all in our heads, but what starts in our heads can affect the whole body.
   Back in 2009, researchers at the Swedish University of Agricultural Sciences at Uppsala recognized that most research in equestrian sciences focused on how intentional signals, given by an experienced rider during training sessions can affect the performance of a horse. The unintentional signals however, had been long ignored. These unintentional signals are even more important in human-horse interactions. We all know horses (and most other animals) can sense what we’re feeling, but does what we’re feeling translate into a physiologic change in the animal? Can our nervousness, our apprehension cause a measurable change in our horses? This group thought so and they hypothesized that a person could communicate anxiety about a particular situation to the horse they were with.

Methods and Materials:
To prove their theory, they took 27 horses and 37 riders, all who were associated with the agricultural college. All the riders had at least 3 years experience with horses, but none were professionals and all the testing was done in the indoor ring where the horses were used to being worked daily. The test was done first with the person leading the horse and then again with the rider in the saddle. Heart rate monitors were placed on the humans and the horses and data was recorded throughout the test. Horse were led or ridden at a slow walk between two cones placed 30 meters apart. When they got to the end of the track they turned around and went back. They did this 4 times. Just before the 4th pass down the lane, the rider was told by the experimenter that an assistant, who had been standing off to the side of the path would open an umbrella as the horse walked past!! The study is quick to point out that, “the umbrella was not opened.” They weren’t testing how scary an opening umbrella could be, cause we all know the answer to that, they were looking to see if anticipating the scary event would affect the riders and would that translate to the horses. 
    In addition to the heart rates of the horse and rider, an unbiased observer gave an overall behavior score based on “(1) the position of the person in relation to the horse when they were leading it; (2) how close to the horse’s head they held the lead rein; (3) the length of the reins if they were riding; (4) the position of the horse’s head; (5) the position of the tail, and (6) the horse’s behavior on a scale from ‘relaxed’ to ‘very alert.’”

Sinus Tachycardia: A rapid heart rate.
    The results were impressive. When looking at the rider, their heart rate decreased from the first time down the path to third time, as they became comfortable with the task at hand, but not surprisingly, it increased during the 4th pass, when they were expecting the umbrella. There was more of an increase in human heart rate if the person was riding the horse as opposed to leading it. So what did the horses think about this? Their responses mirrored their human’s nearly identically. Horses heart rates decreased as they went from the beginning of the test to the third time down the track but whether being led or being ridden, there was a significant increase in the horse’s heart rate on the 4th pass. The authors concluded, “thus the heart rate of the horse increased when the person ‘thought’ the horse might be frightened by the umbrella.”

   So how is it that we are conveying this message to our horses? Are they mind readers? Are we sending telepathic signals warning them about the umbrellas that hide behind every tree, tarp and trailer door? The study did note that while the heart rates were clearly affected, there was no behavioral difference seen in horses but the riders tended to shorten their reins on the 4th pass compared with the 3rd. A subtle cue, yes, but as this only happens when we are on their back, there must be some other deeper connection there.
     The study finished up by stating that the higher heart rate seen in the horses means they were more alert and prepared to react to any danger. This happens in the wild as an adaptive response to signals from other horses in the herd in response to a potential threat. They also point out that other studies have shown that the “startle response” in animals is far more pronounced when they are alert. They propose that a nervous rider may increase the likelihood of an exaggerated ‘startle response” and that increasing our awareness (and trying to control) these unconscious, unintentional signals could help to reduce the number of times a ‘scary situation’ turns into an accident.

    So experts out there have been right all along when they say, “the animals can sense your fear.” There is some science behind what Marissa and Tucker were BOTH feeling. Maybe her knowledge of his past bravery (or lack thereof) was like an experimenter promising a fluttering umbrella, or maybe a subtle cue from him (pricked ears, a little snort) was like a rider shortening her reins. It really doesn’t matter who started it, we know now that the connection is real and if we take a deep breath and try lying to our horses about our own anxieties, we may make it around the lake in one piece!

Like stories about how horses learn from and react to us humans? Check out The Way to a Horse's Heart...Through the stomach or the withers?

You can follow Marissa and Tucker's adventures at Tucker the Wunderkind, a Sidelines Blog by Marissa Quigley.

The Umbrella Study:
Keeling LJ, Jonare L, Lanneborn L. Investigating horse-human interactions: the effect of a nervous human. Vet J. 2009 Jul;181(1):70-1.

The old saying goes, “No hoof, no horse” and truer words have never been spoken. Any horse owner knows that trouble starts from the bottom up and hoof issues can put you on the sidelines for far too long. This is a problem that one of my clients is facing. Her horse is suffering from White Line Disease (WLD) in all four feet and while her farrier and local veterinarian are doing exactly the right things to get her back in the saddle, as a graduate of both the Beginner and Advanced Equine Education Courses she has a thirst for knowledge and asked me for a little more information on the process. And I thought I would share my answer with all of you.     White line disease is a problem of the equine hoof that is seen throughout the world and is still poorly understood by the veterinary and farrier community.  It is characterized by the separation of the inner zone of the hoof wall. This separation that occurs on the solar surface of the hoof can begin at the toe (which is where the old layman’s term “seedy toe” comes from) or the quarter or the heel. The area of separation is then invaded by bacteria and fungus from the environment (remember the separation starts on the bottom of the hoof, which spends most of its time in the dirt). The separation, and infection, can progress proximally up the hoof wall towards the coronary band. Interestingly, the coronary band never becomes infected, which is why the term onychomycosis (a nail bed infection in humans or dogs) is inappropriate to use when describing WLD.

In vet school I was lucky enough to learn equine orthopedics from Dr. Dean Richardson, the surgeon who cared for Barbaro, and if there is one thing every Penn Vet grad remembers about equine orthopedics, its that you have to know your ANATOMY, ANATOMY, ANATOMY! (though all capital letters cannot truly convey the emotion, or volume, with which DWR screamed this during lectures).
So to understand WLD better, lets review the ANATOMY of the hoof as it pertains to this problem. The Solar Surface of the Hoof     The hoof wall consists of three layers; the stratum tectorium (external layer), the stratum medium (the middle layer), and the stratum lamellatum (the inner layer). The stratum tectorium is the thin layer of cells that give the wall its smooth shiny appearance. The stratum medium forms the bulk of the wall and is the densest part of the hoof wall. The stratum lamellatum arises from the laminae, is nonpigmented, and is responsible for attaching the hoof wall to the third phalanx, and is what gives us so much trouble in cases of laminitis or founder. The junction where the sole attaches to the wall of the hoof is formed by interdigitation of lamellae and horny tubular tissue. This is the area known as the White Line, though in real life it is often yellow in color.

So how does separation occur between the sole and the hoof wall? And the question most owners ask, “Why is this happening to my horse?” While there are a lot of theories out there about what causes WLD, none of them have been confirmed. It can affect horses of any age, sex or breed. It can affect one foot or a combination of all four. Horses with shoes get WLD and barefoot horses get WLD. Horses in every country can be affected and you may have one case on a farm or multiple ones. Mechanical stresses that are constantly being put on the hoof can contribute to the separation and chronic hoof problems and poor conformation may also be a cause.     Some people believe that moisture plays a role because, just like Scratches, it is so often seen in horses that spend time in wet paddocks or show horses who are bathed daily. However, it is also seen in arid climates. Moisture may soften the foot, allowing easier access for bacteria and debris, but hot, dry conditions make hooves prone to cracking, allowing the microbes to invade. And don’t try to blame the housekeeper, because WLD is seen equally in areas of poor hygiene as well as clean, well-managed stables.
Not all horses that have WLD will become lame. It is often an incidental finding at a routine farrier appointment. However when the separation becomes so extensive that there is destabilization of the whole hoof, horses will become sore. The diagnosis is made by your vet or farrier examining the hoof and investigating if there is a gap between the hoof wall and the inner structures. Radiographs (x-rays) can be very helpful because they show the extent of the damage and if there are any other structural problems with the hoof or the coffin bone.

Treatment involves opening up the spaces by removing the overlying hoof wall (with a dremel tool). Once every cavity is exposed, topical antiseptics can be used judiciously (no more than once or twice a week) to clear up the infection. Afterwards corrective shoeing will help support the hoof while it regrows the resected portions. Acrylic can be applied to the area to prevent recontamination, or for cosmetics, but should only be used once the infection is completely resolved. 

    Because we don’t know the exact cause, it’s difficult to make recommendations on how to prevent WLD. But daily hoof care on your part and proper trimming and shoeing performed by a well-trained farrier is the first step to recognizing a problem early on. Horses that have had WLD should be monitored all the more closely as the can have spontaneous recurrence of the disease.

            So keep your eyes open and your horse’s feet well cared for and you can stay on the trail or in the ring without problems!