Association is not Causation

The death of Disco music. The rise of Rap. The release of glyphosate/RoundUp herbicide. Drops in numbers of butterflies and pheasants in Pennsylvania. These all occurred on the same timeline. Are they related?

Statistically, yes. They are related but the only thing they have in common is parallel time courses. At the same time there was also a drop in eating fondue and the popularity of bell bottom pants

Where is this going? The point is that just because two things happen at the same time it doesn’t mean they are even connected, let alone causal. There may be a statistically significant link between pretzel eating and alcoholism just because bars have free pretzels but it doesn’t mean cause and effect. All statistical significance tells you is that the connection is probably not due to chance alone. It doesn’t tell you what the connection is.

Pretzel eating causing alcoholism, or vice versa for that matter, seems ridiculous but there are many claims being made about horses that spring from the same faulty reasoning and they often are based on the most dangerously misleading or misunderstood information out there – actual scientific studies. Lay magazines reporting  on scientific studies can be worse yet.

Good science follows the laws of logic and is very careful about how statements are worded but even so it is taken the wrong way. In a scientific study, “associated with” means there is a relationship between two things but it does not tell you what the relationship is. For example, statistically, peanut butter is associated with jelly and both are associated with bread.  None of these factors causes the other. They are simply found together. Association is not causation.

Not understanding that can result in a lot of trouble. An example was the observation that in  some parts of the world when horses develop laminitis the fructan levels may be high in fall pastures. The press was all over this. Even though subsequent studies showed fructan related laminitis is a gut overload phenomenon and about 90% of laminitis cases are not, the fructan “cause” of laminitis refuses to die.

Another example is that lactate causes fatigue and muscle pain. The truth is that high levels of lactate from anaerobic metabolism occur at the same time as peak exertion but the lactate doesn’t cause the fatigue any more than ashes cause fire. It is a marker of the problem, not the cause.

More recently, a discussion arose over a lay article linking metabolic syndrome to environmental exposure. This was reporting on an actual study that found dioxin level in horses’ blood was linked to triglyceride (fat) levels.  However, there was no connection with glucose or insulin and dioxin happens to be a fat soluble toxin that is present  literally everywhere (including at the north and south poles). The actual article stated there “may” be an influence; not that there is one.

The message here is to learn to think critically. Don’t believe the slant every lay article puts on things. Go to the original published study. While you are there, read each sentence carefully and be alert for words like “may”, “might”, “could”, “tends” or “trends” because these qualifiers mean any connections fall short of actually proving cause and effect.

Association is not Causation.

Eleanor Kellon, VMD

 

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Omega-6 Gets a Bum Rap

You have probably read more than once that omega-6 fatty acids are inflammatory. I’m sure I’ve been guilty of saying something to that effect myself. The truth is, it’s an over simplification.

Flax seeds have the ideal balance of omega-6 to omega-3 for horses

Both omega-3 and omega-6 are essential fatty acids. They are called essential because the horse’s body can’t manufacture them. They are also called essential because the body needs them – both of them.

The first step in the metabolism of omega-6 linoleic acid is the production of arachidonic acid. Counterparts on the omega-3 side are DHA and EPA.  This is a multistep process but the first enzyme for these conversions is the same for both omega-3 and omega-6. I’ll come back to that in a minute.

After the production of arachidonic acid, eicosanoids are generated. These are prostaglandins, leukotrienes and a few other minor classes. These are the lipochemicals with active inflammatory effects while those generated from omega-3 have antiinflammatory actions. However, while it is true that there is some evidence diets with high omega-6 are associated with higher arachidonic acid levels that does not immediately translate into higher active inflammatory eicosanoids.

Inflammation doesn’t just happen. It has to be triggered by something – an infection, injury, toxin, cell death. Just having more omega-6 and arachidonic acid around won’t do it. Where the level of omega-6 versus -3 has its major effect is in the production of omega-3 counter regulatory eicosanoids. When there is an abundance of omega-6 they can block omega-3 access to that first enzyme needed to start conversion of these fats into active compounds.

The omega-6 series also does more than cause inflammation. Eicosanoids from omega-6 linoleic acid have some  important beneficial actions. Aspirin can cause an asthma attack because it blocks production of the omega-6 prostaglandin E2 which is a bronchodilator.  Aspirin allows the bronchoconstricting prostaglandins to take over.

Throughout the bodily functions, normal is a balance between chemical mediators and prostaglandin eicosanoids are involved in many reactions. In the kidneys, they play a role in urine production and electrolyte balance. They are involved in noradrenalin modulation and the sensitivity of sensory nerves. Intraocular pressure, pituitary hormone release and insulin action are influenced.

The leukotrienes derived from omega-6 are primarily mediators of inflammation but inflammation is a necessary reaction for defense from invaders, cleaning up dead or damaged tissue, and healing.  https://wp.me/p2WBdh-wv.  They are also involved in stimulating the innate immune system response to bacteria, fungi and viruses.

Lipoxins derived from omega-6 are structurally similar to leukotrienes but they are involved in the resolution of inflammation rather than promoting it. They work together with omega-3 derived resolvins, protectins and maresins to stop the inflammatory process and restore homeostasis.

When a nutrient is essential, there is no good or bad. It’s balance that is important.

Eleanor Kellon, VMD

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Hemp for Horses

Hemp and marijuana are closely related. The recent explosion of interest in legalizing marijuana has indirectly shoved hemp into the spotlight. Several US states were already growing hemp despite DEA objections but in mid December of 2018 hemp production was legalized federally by the Hemp Farming Act provision of the 2018 Farm Bill. Many people have heard about at least one hemp product and been confused by the difference between hemp and marijuana.

Hemp and marijuana are different varieties of the same plant, Cannabis sativa, which have very different profiles of active chemicals

Hemp grows much faster and taller than marijuana. For thousands of years it has been used as a source of fiber for fabrics and paper, more recently as a biofuel and insulation. Hemp has also been used as farm animal fodder. The major difference of interest between hemp and marijuana is low to very low levels of the psychoactive chemical THC (tetrahydrocannabinol) in hemp.

Hemp contains high levels of another cannabinoid, CBD – cannabidiol. CBD doesn’t produce a “high” like THC, but has been studied for some other biological effects. These include treatment of epilepsy, anxiety, chronic and neuropathic pain and inflammation. Of these, only its effects in epilepsy have what is considered to be strong scientific support. There is also interest in CBD for controlling nausea and vomiting.

Despite the lack of good scientific evidence to support the use of CBD oil (there’s actually more for approaches that also use THC), it is widely available on the internet and being touted as a therapy for virtually any animal or human condition that has a component of inflammation, pain or anxiety which you can imagine is pretty much everything. Even colic is on the list, which is an irresponsible and potentially fatal suggestion. Unfortunately, these wildly indiscriminate claims are likely to inflame regulatory agencies and set back efforts to determine what the legitimate uses are.

Hemp seed oil is also being advertised as having the ideal omega-3:omega-6 ratio for horses. However, at 1:3 it is actually good for human but the inverse of what is appropriate for an equine diet. It also contains about 3% of the antiinflammatory omega-6 GLA, gamma linoleic acid. The 3% GLA does not compensate for the inverted omega-3:6 ratio or justify the high price.

It’s not uncommon to see articles discussing both hemp seed oil and CBD but there is no CBD present in the seeds. Further confusing things is products sold as “hemp oil” which are actually fat/oil soluble extracts of the whole plant, not the seeds.

Hemp seed meal, which is what is left of the seeds after the oil is extracted, is being sold as a protein supplement for horses. The residual fat is about 10%, protein 30%, which is similar to other cold-pressed seed meals.  There is also a product called “hemp protein fiber” which is the screenings from meal production and is lower protein because of the hull fragments. Hemp protein has an OK amino acid ratio for horses but nothing to justify pricing over linseed or canola meal.

Finally, there are hemp beddings on the market which are apparently quite absorbent. Unfortunately they are also pretty palatable and impaction has occurred after eating them.

Hemp as a source of CBD may turn out to be very valuable but in the meantime beware of the marketing of superiority for all things hemp.

Eleanor Kellon, VMD

 

 

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Winter Respiratory Health

An elevated concentration of irritants in the air causes measurable lung inflammation in all horses. There may or may not be a true allergic component. Continued exposure can lead to IAD (inflammatory airway disease) or RAO (recurrent airway obstruction) in susceptible horses. These conditions have a considerable impact on the horse’s comfort and performance. There may be increased risk of infectious lung disease or irreversible damage in chronic cases.

A variety of airborne substances have been implicated. Ammonia from bacterial breakdown of urea in urine is a well documented lung irritant in a variety of species. “Organic dust” is also an offender. This includes microscopic particulate matter from mites, plant material (e.g. beta-glucans), feces, bacteria and their products (endotoxin) and fungal spores.

Barns need good ventilation even in winter. If you have window condensation in the barn there’s a major ventilation problem.

A  critical first step in reducing airway irritation is to guarantee good air circulation through the barn.  High moisture levels indicated by window condensation suspend the irritating substances and reduced air turnover allows their concentration to increase.  Other measures to take, especially if you have symptomatic horses, include:

  • Pick out stall wet spots frequently and consider stall deodorizers (even kitty litter works) for ammonia control
  • Store hay in a separate building
  • Use wood or paper bedding rather than straw
  • Do not clean stalls or sweep with horses in the barn
  • Wet hay and bagged feeds before feeding
  • Turn the horse out as much as possible

Several supplement ingredients can help with maintenance of normal lung function in the face of these temporary challenges.  Spirulina assists in the maintenance of a normal, balanced immune response and stabilization of histamine releasing cells.  MSM supports a controlled inflammatory response.  Research has documented low levels of antioxidant vitamin C in IAD/RAO lung fluid and supplementation can help restore this.  Jiaogulan (Gynostemma platensis) is a Chinese adaptogenic herb which supports normal airway dilation for good air flow.

The reaction to the airborne irritants and allergens generates considerable oxidative stress. All living things are equipped with the ability to produce a range of antioxidant defenses but these can be overwhelmed. When that happens, plants offer a rich source of antioxidant phytochemicals to help maintain homeostasis. These include all berries, grape seed and skins, citrus bioflavinoids which work with vitamin C, Boswellia, Turmeric, Ginger and Ginkgo.

N-acetyl-cysteine supports the horse’s ability to manufacture glutathione, an important antioxidant. As an additional benefit, it assists in maintaining a normal, watery consistency to mucus so that it can be moved out easily.

IAD and RAO are common equine respiratory conditions caused by environmental irritants.  Fortunately, there are many things you can do to reduce exposure to those irritants and supplements which help the body maintain normal lung function.

Eleanor Kellon, VMD

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Mid Winter Check List

With all the chores to do, you probably spend as much time at the barn in winter as during warmer weather but you probably don’t interact with your horse in the same way. This can result in some things creeping up on you.

Skin health can be a problem in winter and issues are easy to miss under the heavy coat. When is the last time you actually touched your horse with your bare hands?

The most common problem is Dermatophilus congolensis, aka mud fever, rain scald or rain rot. It’s a bacterial infection that begins as tiny raised scabs which come off with the hair attached to leave irritated areas of raw skin. As the infection advances the scabs become more thick, more adherent and involve larger areas.  Left untreated, it can spread to involve the body extensively, including a scratches-like infection in the lower legs.If not detected and treated early, you can have a nasty surprise waiting for you when the horse starts to shed. Debilitated and immunocompromised horses are especially at risk but it can happen to any horse.

Another problem easily missed unless you actually palpate the horse with bare hands or thin gloves is weight loss. The coat makes it impossible to accurately see body condition. Check over the ribs, along the spine/topline and at the hips.

If the horse is not being worked it is difficult to detect signs of impaired respiratory health from confinement in closed up barns with high levels of irritant gas and particulate matter. A slight clear nasal discharge is normal, like we get a runny nose in cold air, but it shouldn’t be frothy. Any coughing is also not normal, even if infrequent.  You are most likely to notice coughing when they are eating and running around on turnout.

Hoof growth slows in winter, often leading to longer intervals between farrier/trimmer visits. You may not be as regular about picking out and examining the feet. Thrush can easily creep up on you, especially if the horse is not moving around much.  Common problems such as underrun heels, contracted heels and overly long toes will worsen with longer intervals between farrier/trim visits and sooner or later you will pay the price for this with lameness. Consider pulling shoes to encourage the hoof to spread and tighten up that hoof care interval, or learn to do touch ups yourself between visits.

The dry diet, cold water and less exercise can combine to cause GI problems. Make it a point to do careful monitoring of the horse’s appetite, drinking, manure volume and consistency to detect problems early.

Winter horse care is often demanding under unpleasant conditions but if you build surveillance for some common winter issues into your schedule it can head off a lot of trouble.

Eleanor Kellon, VMD

 

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Understanding Fatty Acids

Fatty acids are the building blocks of fats in the same way that amino acids are the basic unit of proteins. When picking a fat for your horse, you should be guided by the fatty acid levels.

The fat content of the horse’s natural diet is quite low – about 4% during peak grazing season and much lower when grass is not growing or forage has been cut and dried. The fat in grasses contains less than 20% saturated fatty acids, primarily palmitic. Of the unsaturated fatty acids, 60+ percent is alpha-linolenic aka C18:3 omega-3 fatty acids and the remainder a mixture of omega-9 C18:1 oleic acid and omega-6 C18:2 linoleic acid.

You have probably heard that omega-6 fatty acids are inflammatory and omega-3 antiinflammatory but it’s not really quite that simple. Both are needed for healthy and  balanced immune activity.

Omega-6 linoleic acid [LA] is converted to arachidonic acid [AA]. This is found in very high concentrations in the brain and skeletal muscles, and in cell membranes. If an inflammatory reaction has been triggered, AA can be a source of immune system inflammatory chemicals but it cannot trigger inflammation by itself. AA is also essential for muscle growth in response to exercise. Training athletes supplemented with AA actually have lower levels of inflammatory markers.  LA is especially important for skin and coat health.

Omega-3 alpha-linolenic [ALA] is also converted into the phospholipids of cell membranes and its derivative DHA is as abundant in the brain as AA [above]. Other derivatives of ALA participate in the homeostasis of inflammatory responses and support the activity of the sophisticated arm of the immune system which in turn makes the nonspecific inflammatory reactions less necessary.

Omega-9 oleic acid is incorporated into phospholipids of cell membranes. Like all the unsaturated fatty acids it help keep membranes supple. It is the most common fatty acid in the popular human Mediterranean diet and associated with healthy lipid profiles in the blood.

Although it hasn’t been formally studied in horses, it is assumed horses can manufacture all the fatty acids they need with the exception of the essential fatty acids alpha-linolenic omega-3, and linoleic, omega-6. Grasses typically have about 4 times as much omega-3 as omega-6 fatty acids.

Horses are fed supplemental fat to boost calorie intake, improve skin and coat health and shine, and provide the essential omega-3 and omega-6 fatty acids. Omega-6 fat may be of additional benefit in active horses, for promoting muscle growth. Good sources include:

Coconut oil: Extremely palatable. Also rich in medium chain triglycerides which are the easiest to metabolize for energy. Low essential fatty acids.

Flaxseed oil: Very high in omega-3 fatty acids.  Omega-3:omega-6 ratio similar to grass. Low saturated fat.

Soybean oil: High omega-6, moderate omega-9 and omega-3, low saturated fat.

High oleic sunflower oil: This specialty type of sunflower oil is high in omega-9 oleic acid (like olive oil) and low in essential fatty acids. This makes it a great way to promote weight gain and coat condition without upsetting the balance of essential fatty acids.

Eleanor Kellon, VMD

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Can EMS Horses Graze Dead Winter Pastures?

Unless you are living in an area with very mild winters, your pasture grasses will shrivel and turn brown over the winter. However, that plant is not dead and horses will be more than happy to eat it. This could send insulin dangerously high for a horse with EMS [Equine Metabolic Syndrome].

It Only Looks Dead

Winter pasture doesn’t look very appetizing and it’s certainly true that it is not as nutritious but with careful planning it can actually be relied upon to reduce the need for hay and other supplemental feeding. The trick is to graze it enough to prevent it going to seed during the regular season then stop grazing long enough for a good amount to accumulate but not long enough for it to go to seed. This preserves the nutritional value as much as possible. The practice is called stockpiling.

If the nutritional value is reduced, shouldn’t that make it safe for EMS horses to graze? Unfortunately, while everything else goes down the one thing that makes the grazing safe or not for EMS horses is high.

Dormant grasses survive the winter depending on their tolerance to freezing.  Freezing expands and explodes cells, leading to loss of fluid and electrolytes.  Grasses increase their freezing tolerance through high levels of simple carbohydrates.  This means their levels of storage carbohydrates, either fructan or starch, depending on the species, will be high.  Even more importantly the level of simple sugar is also high.

These carbohydrates are concentrated in the stolons and crowns of the grass, close to ground level. Under peak grazing season conditions the horse would not graze that close to the ground, clipping grass off at a height of about 2 inches. However, the wilted, soggy  mess of dormant winter grass sits close to the ground and it doesn’t take the horse long to figure out where the most sugary parts are.

Making sure the horse has plenty to eat before turning out on winter pastures will help but it’s no guarantee he won’t eat too much of the high sugar treat.  Snow coverage won’t be protection either.  Many horses are determined enough to paw through the snow and can eat enough to get laminitic. It happens every year.

The cold weather itself may be a risk factor for laminitis since insulins often fluctuate widely in cold weather.  This is on top of the cold induced pain many EMS horses suffer as a result of impaired circulation https://wp.me/p2WBdh-D9.  Don’t compound the risk of painful feet by allowing access to winter grass.

Eleanor Kellon, VMD

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Immune Support

It’s true that your horse cannot get a “cold”/respiratory infection without a virus but all horses carry around a generous supply of both viruses and bacteria. While winter weather can’t cause a respiratory illness, the stress of severe weather coupled with the effect of cold, dry air on the lining of the respiratory tract sets the stage for any waiting viruses or bacteria to take hold by weakening normal immune defenses. Seniors and young horses have an additional risk factor since their immune systems are often not fully competent.

There are a variety of natural and man-made substances which can stimulate various aspects of the immune response but I don’t want to talk about those today. Before they can even be effective the immune system needs to have all the key nutrients it needs to function.

Keeping a horse fleshed out is usually the easiest part of feeding. All it takes is empty calories. An inadequate supply of protein in general or specific amino acids can greatly reduce the strength of immune system reactions. Everything from the multiplication of immune system cells to antibody, cytokine, even mucus production requires adequate protein and B vitamins. Pregnant, nursing, growing and debilitated animals have highest needs. If there is any question of adequate protein, switch from plain vitamin and mineral supplementation to one that includes 20+% protein from vegetable sources and whey for the best amino acid array.

Bio-active whey protein is also potent support for glutathione, the major antioxidant system in the body. Glutathione provides homeostasis for both immune cells and all body cells against free radicals generated during immune reactions. Colostrum does more than supply antibodies to newborns.  It is a specific source of proteins like lactoferrin, complement and proline-rich polypeptides (PEP) as well as cytokines, all of which have immune activity for any age horse.

Essential fatty acids also have profound effects on the immune system. Omega-3s are essential to function of the sophisticated immune system which targets and remembers specific organisms. Omega-6 fatty acids are utilized in reactions involving the primitive immune system which is the first line of defense against invaders. The barrier tissues of skin and mucus membranes are particularly dependent on omega-6.

Fat soluble vitamins A and E require attention. Vitamin A is needed for good immune function in the skin and mucus membranes. E is a well known antioxidant that is particularly critical for the survival of both B and T-cell lymphocytes. These cells have high levels of polyunsaturated fats in their membranes so are especially vulnerable to oxidative damage. All hay based diets are vitamin E deficient. Vitamin A is present in hay as carotene and also loses activity with time.

The immune system can be its own worst enemy because many of the reactions used to defend against invaders involve the generation of high levels of oxidative stress. When this happens, horses can benefit from the addition of plant based antioxidants such as berry powders, Turmeric, bioflavanoids/quercetin, malic acid, N-acetyl cysteine, glutamine, pancrelipase and vitamin C.  Also supportive are arabinogalactans, mannanoligosaccharides and fructooligosaccharides which are naturally occurring  complex polysaccharides from plants which provide gentle stimulation to the rich supply of immune tissue in the intestinal tract – the GALT (Gut Associated Lymphoid Tissue).

The immune system is complex because it has to be but understanding all the nutritional elements it needs to function well is the cornerstone of immune support.

Eleanor Kellon, VMD

 

 

 

 

 

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Hind Gut Health

I have written on this topic for over a decade but continue to encounter many questions and comments that are based on misinformation.

For this discussion I am going to define a normal hind gut as one that is functioning normally – normal manure in normal amounts, no excess gas or bloating, normal gut sounds on examination, no abdominal pain (colic), healthy weight for the amount of food being consumed – although other things can affect weight.

Subtle behavioral signs of trouble include tail swishing or docking, kicking back or at the belly with ears pinned, looking at the flank. Sensitivity to touch or pressure (e.g. girth), gait disturbance or lameness are **not** signs of gut disturbance especially with no other signs of intestinal disorder. [Note: Subtle behavioral changes have been documented with starch feeding but that was a diet of almost 50% barley!]

The disorders du jour are acidosis and hind gut ulcers – both nonexistent the way many people are thinking of them. You may have read about horses having  behavioral or movement issues related to “sublinical acidosis” but subclinical by definition means no observable signs.

The pH of the hind gut varies depending on diet. There are no acid secreting cells and material entering from the stomach and small intestine is alkaline. Diets with high levels of simple sugar and starch reaching the hind gut naturally cause a more acidic environment because of the way they are fermented. There are no consequences of this unless pH drops low enough to damage the intestinal lining, at which point you see fever, colic, sepsis, diarrhea and laminitis in extreme cases. The important point here is that acidosis does not, and cannot, occur on diets with reasonable levels of starch and simple sugars. It takes very large amounts to produce enough acidosis to cause clinical signs and those signs include fever and diarrhea.

You may have seen claims subclinical acidosis is related to stereotypical behavior like cribbing, wood-chewing and weaving. There are zero actual studies looking at degree of acidosis and stereotypical behavior. One study found high grain feeding during weaning increased cribbing but this could not be differentiated from low forage access and long periods with nothing to chew on for distraction. A study of 743 young racehorses on two tracks found a connection between using wood shavings and stereotypical behavior but no influence by % of grain and forage fed. Similarly, other studies have found a decrease with more frequent meal feeding but not by composition of the diet.

A supplement manufacturer has reported high prevalence of hind gut “ulcers” based on observations made on horses going through slaughter houses.  This entity does not appear in any veterinary medicine or pathology textbooks except for colonic ulcerations caused by phenylbutazone use.

A subsequent study lead by Kerbyson in the UK examined 56 horses euthanized for reasons unrelated to the GI tract and looked for idiopathic (no obvious cause) colonic ulcers. They found 21% had ulcerations clearly related to parasites or sand. Only 5% had ulceration with no obvious visible cause (? autoimmune disease, ? phenylbutazone use) which is a far cry from the 63% the original survey reported. In fact, the supplement manufacturer’s website has since switched from mention of “colonic ulcers” to the hind gut being the site of various specific GI pathologies such as parasites.

Once mistaken information has been widely circulated it is difficult to get rid of it but the time has come to stop worrying about hind gut acidosis or ulcers – and buying supplements to address them.

Eleanor Kellon, VMD

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Winter Laminitis

Veterinarians working with many laminitic horses are well acquainted with the problem but others are unfamiliar with it.  It’s a laminitis-like syndrome triggered by cold weather.

Horses normally have a very high tolerance for cold.  In all species, cold causes a reflex shunting of blood away from the extremities and toward the core to limit loss of body heat. Healthy horses prevent the hoof tissue from being damaged from low blood/oxygen supply by using local arteriovenous shunts – pathways which allow them to divert blood quickly back to the veins for return or to send it to the local tissues. When low blood supply reaches a critical level, the arteriovenous shunts to that part of the hoof can close, perfusing the tissue.

The only adverse effect of cold weather and reduced blood flow to the hoof in healthy horses is slower hoof wall growth. In horses with metabolic issues that result in high insulin levels, it may be a different story.

We don’t know all the details of the mechanism but it is clear from research that high insulin can cause laminitis. We also know that even if they have never had a full blown laminitis episode these equines can show similar abnormal structure of their laminae. One thing we do know about it is that levels of endothelin-1 are greatly elevated. This is a chemical in the body which causes blood vessels to contract down. It has also been shown that the vessels in the hoof become more sensitive to other messengers that cause contraction. These changes may interact with cold induced blood vessel constriction to cause a critical interruption of blood supply to the hooves of those horses.

Horses with cold induced hoof pain/laminitis show obvious lameness, foot pain and often typical laminitis stance but without bounding pulses or heat in their feet. In milder cases it may be mistaken for the sensitivity to moving over frozen uneven ground that all horses show. However, it doesn’t go away on level surfaces. There is variability in individual sensitivity to cold but signs may appear beginning at 40F [4.4C].

Even horses that have their insulin usually well controlled by a low carbohydrate balanced diet can be susceptible. This may be because cold weather has also been observed to often cause wide swings in insulin levels and/or because of previous damage to the circulation in the feet.

The first step in helping these horses is protecting their extremities from the cold. Leg wraps such as lined shipping boots work well and are safe to leave on because they won’t slip out of place and cause uneven pressure on the tendons [aka “bandage bows”]. Boots with pads and socks or fleece lining are essential.

The equine can be supported nutritionally by supplements which encourage the production of nitric oxide. Nitric oxide is a vessel dilating messenger that is the natural counterbalance to endothelin-1.  The herb Gynostemma pentaphyllum (Jiaogulan) is a powerful support for nitric oxide. This is helped by providing the precursors for nitric oxide in the form of L-arginine and L-citrulline. Antioxidants also combat oxidative stress which inhibits the activity of the enzyme that produces nitric oxide inside blood  vessels [eNOS – endothelial nitric oxide synthesis].

Winter laminitis has historically been regarded as very difficult to manage but understanding the vascular mechanism has led to significant strides in helping these horses balance the forces affecting the blood supply to their feet.

Eleanor Kellon, VMD

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