Dressage places unique demands on the tendons, ligaments, fascia and muscle
The exquisite control and at times suspension required of a dressage horse seems effortless during a good performance but in reality requires tremendous muscular strength, nervous system coordination and strain on tendons and ligaments.
When we think about problems with performance horses, joints immediately come to mind. Dressage horses are no strangers to joint problems but the possibilities go beyond that.
Whether exercise-related muscle strain or an inherent issue with muscle metabolism and performance, muscle is a common reason behind a variety of performance issues including poor endurance, resistance and inability to progress in training milestones. Before assuming the horse “doesn’t have what it takes” consider support for muscular function. You’ll know in a month or less if it’s going to help.
The connective tissues tendon and ligament are strong and resistant to damage but the high demands put on tissues like the hind limb suspensory ligament in dressage horses can begin to cause injury. High demands on the tissue means higher specific nutritional requirements. The fascial sheaths throughout the body encircling both muscles and tendons/ligaments are also a form of connective tissue. They used to be considered inert but recent research is showing fascia can actually contract and sustained contraction can interfere considerably with muscle, tendon and ligament function https://www.fvpt.com/myofascial-release .
The solution to sun bleaching is more of the protective pigment melanin. The two minerals critical to the initial steps of melanin production are copper and zinc. It’s no coincidence that deficiencies and imbalances in these two minerals are extremely common, as is excessive iron intake which can block their absorption. https://uckele.com/articles/summer-skin-and-coat-care/ . Start with 100 mg Poly Copper and 300 mg Poly Zinc.
Because testing for hormonal disease in horses is often triggered by the horse developing laminitis, the effect of pain on test results is always a concern.
A 2020 German study looked at hospitalized horses in pain from various conditions including colic, laminitis and orthopedic conditions. All horses had been in the clinic for at least 24 hours. Horses were 15 years old or younger with no clinical signs of PPID (Cushing’s disease).
They were tested by both baseline ACTH and ACTH after TRH stimulation, both while in pain and after they had recovered. There was no difference in test results regardless of pain intensity, so no effect of pain in this study.
However, timing may be important. This study found acute pain resulted in markedly elevated cortisol and insulin resistance. Since acute stress, wounds etc. can cause the adrenal glands to release cortisol without ACTH increase, it’s unclear from that study if acute pain will influence ACTH – although it certainly increases insulin.
A 1980 study on the responses to a low grade electrical current showed there was an ACTH response to this type of acute pain. We also know that both ACTH and cortisol levels are more likely to be greater than normal ranges in acute illness.
In summary, while there are still some gaps in the available information, testing for both ACTH and insulin levels should be avoided in the first 24 hours after onset of a painful condition. Beyond that time, ACTH can probably be tested without interference. Insulin may be tested after the pain has stabilized, even if not gone entirely.
A study that will be published in the July issue of the Journal of Equine Veterinary Science has found that none of the currently available tests for equine lung allergic disease are helpful.
The study looked at 15 horses – 6 normal controls and 9 with varying degrees of equine “asthma” aka Heaves, RAO, equine COPD.
The testing methods evaluated were two different serum IgE antibody tests, intradermal skin testing and a functional in vitro test where blood is incubated with each suspected allergen then tested to see if the cells had released histamine. They also checked the horses’ sensitivity to inhaled histamine and to two different inhaled allergens.
The sensitivity to inhaled histamine was significantly greater in the horses with known lung disease than in the normal horses. It was the only testing method that could accurately differentiate between normal and affected horses. However, this test works by triggering respiratory distress and is not likely to be a popular diagnostic method. It was used in this study to confirm the clinical diagnoses as either normal or asthmatic.
The two blood tests for IgE antibodies are what most people are familiar with for allergy testing. There were just as many, if not more, positive reactions in the normal horses as in those with lung disease. The same thing happened with the functional in vitro testing. Intradermal skin testing, which is very reliable for skin reactions, also showed more positives in the normal horses and few in either group showed a skin reaction to mold – a known problem with lung disease. However, all horses except one in the asthma group showed a strong reaction to mosquito allergens.
In the inhaled allergens test, the horses were exposed to the substances which gave their highest test reaction on the functional in vitro test and also to another positive allergen selected from their test results. Two of the asthmatic horses had delayed reactions to the first test but none reacted on the second test.
The authors concluded: “In this study, no agreement was found between the results of four different, commercially available allergy tests for equine asthma. None of the four allergy tests could differentiate reliably between healthy and asthma-affected horses”.
Part of the problem is that both the antibody tests and the functional in vitro test are focusing on IgE, the antibody of immediate type allergic reactions, like what happens with extreme peanut allergies on your first bite. There is quite a bit of evidence that equine allergic lung disease is of the delayed reaction type. Another problem is that antibodies only mean the horse has been exposed to something. They cannot predict allergic reactions.
The bottom line is that, as with as with food allergies https://wp.me/p2WBdh-15k , blood tests cannot be used to identify what may be triggering your horse’s reactions. Save your money. Even more important, avoid the angst that comes with staring at a long list of “positive” test results which don’t mean anything.
Sugar phobia has reached a point where virtually any problem with a horse’s hooves may be blamed on sugar.
From thrush to weak laminar connections, sugar is being blamed for hoof problems. This often comes with stories of how horses have improved once the diet was changed. However, sugar is rarely the culprit here.
“Sugar” comes from both things high in simple sugars, like molasses, and foods high in starch because the horse’s body digests starch to the sugar glucose in the intestinal tract and that is what gets absorbed into the blood. Sugar is as essential to the life of plants as it is to animals so everything has it but in varying amounts.
The sugar-hoof connection is via insulin. Sugar causes insulin release to varying extents depending on the individual. Sustained exaggerated insulin responses lead to overt laminitis or a smoldering condition where laminar connections are weak and stretched. This scenario is a genuine connection between sugar/starch and hoof health but it only applies to the 10 – 12% of the equine population that actually has those exaggerated insulin responses. If the horse has normal insulin testing, it’s not sugar causing the problems.
Other possible factors include:
Moisture: Change from pasture to a dry lot or track typically means a drier environment
Protein/amino acids: Feed changes may have benefited the protein intake or amino acid profile. For example, if you changed from grain to a balancer that has methionine this could be helpful. Just eliminating grain and replacing with hay increases protein intake. A pound of a 12% protein grain has 54 grams of protein and as many as 2.55 Kcal. A pound of 10% protein hay has 45 grams of protein but you have to feed three times as much to match the calories so protein intake jumps up to 135 grams!
Minerals: This is probably where most of the differences originate. Whether you take the horse off pasture or bagged feeds you are reducing the iron intake significantly and also manganese in many cases. These two mineral excesses can worsen the already existing copper and zinc deficiencies in many areas. Feeding change recommendations also often include adding a high zinc and copper supplement.
Better hoof care: On finding issues, your hoof care professional may shorten the interval between trims which can make a huge difference.
Less movement: Movement is good for hoof health, as long as there is a good trim and the feet don’t hurt. Horses with any hoof problem, like negative palmar angle and irritated deep digital flexor tendon, can and often do become more lame when turned out because they are moving around a lot more.
If you suspect a horse has hoof problems related to insulin responses, have him tested. Only lab work can really answer that question. If it’s not insulin-related, consider the points above to attempt to determine what’s going on with the horse.
How much flax seed do you need to feed to match intake from grazing?
We know that omega-3 and omega-6 fatty acids are essential elements of the diet for mammals because their bodies cannot synthesize them. What we don’t know is how much of each is required for health. No research has been done.
We can look at the omega-3 and omega-6 content of the horse’s diet though. Grass is by far the major portion of a feral equine’s diet. Young growths of grass are about 4% fat with 75% of that omenga-3 as alpha-linolenic acid. This high level of intake is not available all year but it is representative of peak nutrition.
How much is in the grass is one thing but we don’t know how digestible it is. To get around this another way, a study recently reported at the Equine Science Society meeting fed stalled horses an omega-3 supplemented feed and compared their blood levels of omega-3 to horses on pasture.
It was found that feeding a 1000 pound horse the equivalent of 4.5 ounces of flax seed or a supplement based on flax seed resulted in blood levels of omega-3 comparable to horses on pasture.
Insulin dysregulation [ID] is a term coined in a 2014 publication to describe horses with abnormal levels of insulin. Elevated insulin used to be considered to mean a horse is insulin resistant, and in many cases it still does, but there is emerging information there can be other mechanisms behind an elevated insulin.
“Insulin resistance” means the insulin responsive cells (muscle, fat, liver) do not take up glucose normally in response to insulin. As a result, the pancreas puts out higher levels of insulin until the glucose blood levels normalize. This is one explanation for why blood insulin levels would be higher than normal.
The level of insulin in a horse’s blood is a function of both how much is being secreted by the pancreas and the rate with which the liver, kidney and muscle clear it from the blood. There is some evidence to suggest there may be decreased clearance of insulin in horses with high insulin levels. However, abnormal clearance as the primary cause of high insulin blood levels has never been proven. It is known in people that reduced insulin clearance is part of the insulin resistance picture; likely a way the body helps to keep higher levels of insulin circulating when needed.
Intestinal hormones called incretins can also signal the pancreas to release insulin. When the horse eats, incretins are released into the blood by the intestinal tract. Two of these incretins, GLP-1 and GIP, cause release of insulin from the pancreas. It has been found that some ponies that test negative for insulin resistance with intravenous testing will have positive tests for hyperinsulinemia (high blood insulin) after being given oral grain or dextrose. The abnormally high insulins after feeding have been linked to higher levels of active GLP-1 incretin. On the other hand, a similar study in full size horses with EMS (equine metabolic syndrome) did not find any significant connection between higher active GLP-1 and high insulins.
Because high blood insulin after eating or oral dextrose dosing does not necessarily mean the animal will test positive for insulin resistance by intravenous testing, and slow clearance of insulin from the blood could cause high insulin, the term “insulin dysregulation” was suggested to describe all horses with hyperinsulinemia, regardless of the cause(s).
Personally, I don’t think this is a good term. Dysregulation implies there is something abnormal going on. A 2015 study by deLaat et al found that the non-IR ponies with high insulins on oral testing were also absorbing increased amounts of glucose. In that scenario, the higher levels of GLP-1 and insulin could be considered an appropriate response to the higher glucose, not “dysregulation”. The dysregulation in that case involves glucose absorption, not the reaction to it.
Similarly, if reduced insulin clearance is proven in horses with high blood insulins, it is not necessarily a “dysregulation”. There may simply be a limit to how fast insulin clearance can occur. Alternatively, it may be entirely normal for insulin clearance to slow down when there is a situation of high glucose.
To put it another way, if insulin levels were truly being abnormally regulated with no connection to blood sugar it would show up in the blood glucose. Too much insulin would cause low blood sugar and too little would result in high levels. We don’t see that.
It’s important to understand that having high insulin may not necessarily always mean there is insulin resistance, if only so that you do not become confused by seeing the term insulin dysregulation. However,the change in terminology from insulin resistance to insulin dysregulation looks premature.
In any case, the bottom line for the horse is the same. High insulin is a risk factor for laminitis and the best way to combat it is with an appropriate diet and plenty of exercise – regardless of what is causing it.
The term is new but the concept is not. Postbiotics are substances found in the culture medium when probiotic bacteria are grown. The more familiar term, which you can find on the ingredients list of many digestive products, is fermentation products. When a specific component is of interest, it may be called a fermentation extract.
Fermentation is basically the process of growing microorganisms. Humans have been fermenting foods as a method of preservation for centuries. Examples include cheese, tofu, pickles, yogurt and sauerkraut. Common examples of food fermentation products are vinegar and alcoholic beverages.
Go here to see a detailed scientific article on postbiotics. Here, I will discuss an example probiotic bacterium, Bacillus licheniformis.
B. licheniformis is probiotic for both humans and animals. It is also commonly found in soil. It is a proven immune support and increases weight gain in young animals. B licheniformis has been found to suppress numbers of potentially harmful organisms in the intestine and increase the populations of beneficial strains.
The cell-free postbiotic fraction of B. licheniformis cultures has been found to effectively degrade and neutralize Aflatoxin B1, the most potent and dangerous fungal toxin. This activity is greatest at body temperature. Aflatoxin can kill in levels as tiny as 10 ppb (parts per billion).
B. licheniformis cultures contain the starch digesting enzyme amylase as well as several different protein digesting proteases. The proteases from B. licheniformis are capable of breaking down even proteins with very poor digestibility such as keratins from hide, hair or even feathers.
Supplements containing fermentation products are already providing the benefits of postbiotics but as interest in this field grows we may see more and more specialized extracts emerging to assist with things like organism control and detoxification.
Use Caution Mixing Chastetree Berries With Pergolide
Chastetree berries (CTB), aka Chasteberry, aka Vitex agnus-castus is an herbal remedy I first published about using in horses with PPID (Cushing’s) back in 2000. It had been determined that CTB could help normalize prolactin levels by binding to dopamine receptors in the brain. Low dopamine activity is at the root of PPID so I decided to try it.
Vitex flowers and berries
The initial trial was an observational study. All horses were correctly diagnosed but follow up blood work was not standardized. Emphasis was on signs/symptoms. Response was very positive, especially with coat and foot comfort, but even in this short preliminary study I noted it may not be appropriate for advanced cases, and of course a lot more work needed to be done. There was also concern about how it might interact with pergolide since both act by binding to dopamine receptors.
Since then, a study out of New Bolton found no benefit but used advanced cases and graduated doses of pergolide compared to a set dose of CTB. The Laminitis Trust in the UK studied horses for at least a year on CTB and contradicted the findings of that study. They confirmed obvious benefits with symptomatology but no consistent effect on hormone levels like ACTH.
The latest study looked at confirmed PPID horses on CTB alone, CTB plus pergolide or pergolide alone. Horses on both had better resolution of the abnormal PPID coat but horses on CTB alone or CTB + pergolide had much higher ACTH levels than pergolide alone, indicating CTB can likely interfere with the effects of pergolide. The effect was particularly obvious when the seasonal ACTH rise was approaching.
Pergolide is the gold standard treatment for PPID/Cushing’s and can control the abnormal hormone output from the pituitary. CTB has never been documented to do that, and now it appears it may actually interfere with pergolide effects. This is not surprising since it is competing with the drug for binding sites on dopamine receptors but its effect when bound is apparently not as strong.
The bottom line here is that CTB alone is not an adequate treatment for PPID. Symptoms may improve for a while but the abnormal growth in the pituitary goes unchecked and when CTB stops working the process is much more difficult to get under control. I’ve seen that happen. This new research also shows you must be careful in combining it with pergolide because the CTB may block the drug’s effects.
A common concern this time of year is horses that lack energy for exercise.
There are no apparent health or lameness issues but the horse is either “flat” or starts out well but hits a wall that is at a level of exercise below where they normally perform. What’s wrong?
Is it just too hot?
Could be! The horse is a very large animal and this makes it difficult to dissipate heat. Horses expected to work in the heat should be gradually accustomed to it by step wise increases in work duration and intensity. An important adaptation that occurs is development of an extensive system of blood vessels in the skin. These supply the sweat glands and also radiate body heat from the hot blood on the surface to the surrounding air.
Sweating is the major way to control heating but causes large losses of water and salt
Conditions can be dangerously hot even for accustomed horses. A good rule of thumb uses a heat index calculated by adding the temperature (in Fahrenheit) and the relative humidity. If 120 or less, no barrier to heat dissipation. If over 150, especially with high humidity, the horse will have some difficulty cooling. Over 180, cooling mechanisms are severely compromised and the horse should not be worked. Flagging energy and slowing down will be the first sign your horse is overheating. Heed it.
Is fluid topped off?
Exercise research has documented that as little as 2% dehydration will compromise performance. Work at low and moderate speeds will be affected more than high intensity efforts. This level of dehydration occurs even before you can detect a problem with the skin pinch test so it’s easy to see how dehydration can easily be a problem with work in the heat.
Providing plenty of fresh, clean water whenever the horse wants it is obviously important to avoiding dehydration but it’s not the whole story. To retain that water in the body the horse needs adequate sodium. The major electrolyte lost in sweat is sodium and it is also highly deficient in both hay and concentrate feeds.
I use a 2-2-2 rule to help guard against dehydration – 2 oz of salt the night before a competition or heavy work, 2 oz the morning of and replenish with an electrolyte https://uckele.com/pro-lyte-10lbs.html correctly balanced for sweat if work is longer than 2 hours.
Is the gas tank full?
Many people today are feeding diets designed to limit starch and sugar intake. There is a lot to be said for this but it can sometimes backfire if the horse is in regular work.
The major fuels for muscle work are fat and glucose, with branched chain amino acids also contributing. The fat for muscle work is liberated from fat deposits throughout the body and there is never a shortage. Glucose is taken from the blood but primarily from glucose stored in the muscle as glycogen. Glycogen in the liver is also used to keep blood glucose normal. Glycogen stores are limited so this is the fuel with the potential to limit work. Fat cannot be used to replace glucose. There is always a baseline glucose requirement.
Glycogen stores are lowered by work and need to be replenished. The very low sugar and starch diet may not be able to keep up with losses. Timed feedings can get maximum benefit from a higher carbohydrate meal and also avoid aggravating insulin resistance. Feed 1 to 1.5 lbs of beet pulp (dry weight) with 1 to 1.5 pounds of plain oats within the first hour after work is finished.
There is a window after exercise where muscle takes up glucose very readily. Even insulin resistant horses can receive extra carbohydrate in that time frame. The oats are easily digested to glucose to begin replacing glycogen. The beet pulp is fermented to acetate which is more slowly released and can be used instead of glucose for energy functions, freeing up glucose for glycogen. Studies have confirmed acetate supports the glycogen replacement process. As a plus, you can get water and electrolytes into the horse at the same time – which research has shown is also important for replenishing glycogen. This meal is also ideal for rest stops on long rides.
The above three issues account for the vast majority of horses with energy issues in the summer. If you are having problems, consider them first.