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How safe is your horse's immune system amidst emerging viruses?

Posted on April 06 2020

A number of years ago, I was blown away by training I undertook using a Darkfield microscope, to analyse my own freshly taken blood. The view of my own blood was fascinating, an almost 3 dimensional world of cells, organisms and exciting, unknown shapes. I suddenly began to understand the fragility and co-dependence of the life force all around and within us. A world formed by the decisions we make that impact the health and wellbeing of every cell in our body.

Coronavirus in Horses | Probiotics for Horses | Horse Health | MicromedFast forward to 2020, and the emergence of a highly contagious virus, of microscopic size. A living organism composed of strands of genetic material (RNA) wrapped in an envelope of proteins. If you were lucky enough to view it under a microscope, you would have observed a circular cell shape with extensions, made of protein, protruding outwards, much like jewels on a crown. This, is the corona virus, derived from the latin word corona, meaning garland or crown, and composed of a group of different viruses with similar genetic make-up. One of which is equine corona virus, also known by some as the ‘lying-down disease’.

It was only with the introduction of the electron microscope in 1931 that the first virus was ever seen. Unlike bacteria, that are able to replicate all by themselves, viruses require a host cell, such as those that line the gastro-intestinal tract, or the respiratory passages of your horse. First, the virus needs to find an immune-compromised horse, and attach to the cell-receptors on the cell. In a healthy horse of course, the ‘B’ cells, that form part of the horses’ immunity, would recognise the invader, attach to it, coat it in antibodies, and render it immobilised. The equine corona virus, through this process of ‘neutralization’, can then no longer multiply or invade other cells. Simple process right? What could possibly go wrong?

The horse’s defence artillery in the form of white blood cells, antibodies and other substances that fight off infections and reject foreign substances, should be able to generate a strong enough barrier to obstruct a virus. Why do only some horses become immune-compromised, allowing the virus entry to the body and subsequently occupy the cell receptor sites, allowing access for the cells to infiltrate and replicate. In equine corona-virus, just like the Wuhan human corona virus we are currently witnessing, the virus uses the hosts (be it horse or human) cellular energy and protein mechanisms, to create thousands of disease causing virus particles, that travel directly to the gastro-intestinal tract, and the respiratory system.

If we know the main factors in immune-compromised horses are stress, mal-nutrition and age, followed by negative lifestyle factors that directly or indirectly compromise immunity, surely the sensible approach is to address these areas where possible to minimise their effect. In order to preventatively treat our horses we need to understand what causes our horse stress? What are the factors at play if a horse is malnourished? How do you adopt a protocol to enhance the wellbeing of an ageing horse?

Could it be that there is currently a disconnect between a horse-owner understanding what the factors are and exactly what they could do today to preventatively correct these issues. So, as I consider the implications of equine corona virus for horses, the analogy that springs to mind is 'The ambulance at the bottom of the cliff…' (Joseph Malins, 1895). = a failure of timely intervention resulting in unnecessary casualties and consequences.

Having read the literature on corona-virus it seems the best advice on offer are strategies that only seem to involve the ambulance at the bottom of the cliff, or in other words, disease control and bio-security strategies, once the horse is actually infected with the virus.    

If you have the commitment to understand these factors and the courage to embrace change, then there is hope.       

You see, viruses are clever and once they reach the cell receptors, they have evolved to be able to interfere with the signalling pathways of the horse’s own protective immune system. Therefore rendering the vital communications between immune cells dysfunctional. This is how the current corona viruses are able to outwit protective immune systems, killing thousands and infecting millions. Luckily with equine corona virus the statistics don’t look too bad at this point in the virus’ evolution - but the potential is there for it to become a major problem.  

The first case study of corona virus was linked to an equine illness in 2000, involving a quarter horse filly who developed severe diarrhoea at 2 days old, deteriorated quickly and was subsequently euthanized. The same year, an Arabian foal with diarrhoea and fever was confirmed with a 90% genetic similarity to the bovine corona virus. Due to the virus being different enough to the bovine corona virus, equine corona virus came into being, and it was even suspected by some that it jumped species from cattle to horses. In 2010, it suddenly starting appearing in adult horses in America, then Japan, then Ireland, affecting a wide range of ages.  It seemed however that only 50% of those diagnosed, develop symptoms, ranging from diarrhoea, anorexia, mild colic-like symptoms, lethargy and fever. The other 50% were symptom-free.   

Perhaps it is an opportune time to focus on the factors that can create stress in a horse, and at the same time understand that stress is not an isolated trigger. It is a process that manifests in the body and can take many pathways all with an end result of ill-health.  

As we can all agree, our horses live a life now that is often so far removed from that of their ancestors. It may be pertinent to reflect for just a moment, on the possible equine ‘weaknesses’ that have developed over many years, weaknesses that the corona virus could definitely use to their advantage.  

Performance horses that were found to exhibit ‘some’ level of gastric ulceration was confirmed at 90%, in a 2005 study, detailed in the Journal of Equine Veterinary Science. This in itself shows that there is an implication of performance horses being under a high level of stress. MicroMed for Horses | Equine Ulcers | Health Conditions in Horses

Images of the stomach of two horses obtained by using a 3-meter gastroscope. The lining of a healthy stomach is shown on the left. The right image is of the same region of the stomach of a Thoroughbred racehorse with severe gastric ulceration. Image provided by the Center for Equine Health.

Additionally, high levels of the stress hormone cortisol, breaks down the mucosal lining of the gut, resulting in leaky gut (Increased Intestinal Permeability), which in turn can lead to malabsorption and consequently malnutrition. Other consequences of a leaky gut can vary from allergies, skin issues, gastro-intestinal disturbance or ulcers. Once a leaky gut occurs, it is rarely diagnosed and therefore rarely treated with a restorative gut health product, that would restore immunity to a large degree, in our equines.

If a horse is on a ‘two meal a day regime' as opposed to small amounts continuously, or foraging, this in itself, creates a stress on the digestive system because there is not enough food to soak up the gastric acid secretions, resulting in gastro-intestinal damage. Considering 70% of the immune system is found within the layers of the intestinal lining, we definitely want to look after this area.

Similarly, diets too high in carbohydrates, primarily grains, and fed infrequently in large amounts, leads primarily to high gastric acid and low saliva production (alkaline), and secondarily to only semi-digested carbs entering the cecum and large intestine. If this occurs you then have a situation of high lactic-acid and gas, low pH and a build-up of incorrect microbes, as the beneficial microbes find the pH unbearable. Unfortunately, many a horse will then suffer hindgut acidosis, colic and ulceration. Where the horse may respond with heightened sensitivity to touch in certain regions, it indicates there may be a problem, as does very sensitive withers or chronic sore backs. In addition, extreme exercise and long-distance hauling, transportation, trailing without adequate snack breaks, can all create stress and therefore increased levels of stomach acid. How does this affect immunity? Again - look at gastro-intestinal health as a whole and implement dietary changes if necessary.

Stall habitation, can be stressful and uncomfortable to horses who evolved with fight or flight reflexes, and when unable to ‘flee’ in the face of a scare or fright, this can create a continual low-grade stress. Perhaps the arrangement can’t be changed but natural support for the nervous system can be given, such as chamomile, hops or valerian.

Medications such as sedation, vaccines, antibiotics, de-wormers and NSAID’s all reduce or kill the gut bacteria creating inflammation and leading to gut dysbiosis and possibly leaky gut. I am not advocating we no longer use drugs when necessary however if we practiced more preventative care perhaps we would not need the ambulance at the bottom of the cliff.

Changes in herd hierarchy or social interactions can also cause your horse undue stress, but could be ameliorated with a dose of Bach Rescue Remedy for example or a homeopathic remedy, on the day of change.  

This brings us to older horses with impaired immunity. Over time, body systems become overwhelmed - liver, kidneys, gastro-intestinal system all accumulate toxicity. Many feel that vaccinations, dewormers and the myriad of medications given over time are necessary and I agree. However, I hasten to add - if we were able to treat preventatively, rebuilding the gastro-intestinal tract and combatting intermittent inflammation, detoxing the liver and kidneys, ensuring we have the correct balance of microbes for ideal immunity, you could live in the knowledge you are taking every step to ensure your horse has the best chance against opportunistic bacterias, fungi and viruses such as corona.  

If you are unable to reduce most of the stresses you believe your horse to be under then simply give a digestive system support in the form of a gut health supplement every six months or so. There are so many great herbs for health and repair. You can reduce inflammation with slippery elm, heal a leaky gut with the likes of L-glutamine or butyric acid, provide beneficial bacteria to rebalance normal microbiome, and supplement with zinc and other minerals, crucial for healthy gut lining and immunity. You can even purchase a gut support supplement that has all of these in it.

Micromed for Horses | Medicinal Equine Herb Garden | Horse Friendly Pastures

We can all take simple steps, such as allowing our horse to graze on the likes of dandelion leaves, marigold, or comfrey, all of which are available in most wild pastures. You could start growing them in the hedgerows of your horses paddocks.  Allow the paddock to re-establish itself as a herbal apocathary - what a wonder to behold. It’s an easy choice for some - immune-suppression or immune-stimulation - we know which one we would choose, it just involves a commitment, a timing that is right and a long-term vision. The crucial part we must play immediately is minimising stress levels in our horses, maximising good nutrition, taking the immune-suppressing load off the horse by working on gut health, liver and kidney health and beneficial microbial communities, along with creating a fear-free environment that is as close as possible to their wild origins. Perhaps at that point, to view equine corona virus under a microscope will become a point of fascination and not a point of fear and concern.