Natural defences

THE IMMUNE SYSTEM

A horse with a strong immune system can fight off harmful outside influences. The immune system has a sophisticated process of keeping harmful viruses and bacteria at bay. But how does a good immune system ensure that a horse will get sick less often, or not at all, or will recover quickly? And what does a good immune system require? Dr Wendy Wambacq is a veterinary specialist in the immune system. In this article, we discuss the immune system and its importance on gut health.

THE IMMUNE SYSTEM

WENDY WAMBACQ COMPLETED HER STUDIES IN VETERINARY MEDICINE IN 2011 AT THE UNIVERSITY OF GHENT. AFTER TWO YEARS OF WORKING IN PRIVATE PRACTICE, SHE BEGAN A RESIDENCY WITH THE EUROPEAN COLLEGE OF VETERINARY AND COMPARATIVE NUTRITION, EARNING HER CERTIFICATION IN VETERINARY NUTRITION IN 2016 AND BECOMING AN ICREO-CERTIFIED VETERINARY OSTEOPATH IN 2018. IN 2021, SHE OBTAINED A PHD IN VETERINARY MEDICINE, FOCUSING ON THE RELATIONSHIP BETWEEN NUTRITION AND THE IMMUNE SYSTEM. WENDY CURRENTLY WORKS IN RESEARCH AND DEVELOPMENT FOR CAVALOR. As Dr Sherry A. Rogers said in 2002, “The road to good health is paved with good intestines”. And she’s right! In recent years we’ve become increasingly aware of how important a healthy gut microbiome is to maintain a good immune system. It’s all about maintaining the right balance. A well-functioning immune system will detect and destroy pathogens like viruses and bacteria. It also creates a certain tolerance. It is important that the immune system “tolerates” the body so that there is no inflammatory response when it comes in contact with, say, a fat cell. At the same time, we don’t want the immune system to defend the body from nutrients, which are also exogenous, as you don’t want to be in bed for two days recovering from your immune system’s defence response to some yoghurt full of good bacteria.

Good bacteria = good defences

First and foremost, a healthy immune system must be able to differentiate between what’s good and should be tolerated, and what’s dangerous and requires a response. And if that weren’t complex enough, the immune system must also “remember” everything with which it has ever come in contact. A well-functioning immune system forms a strong barrier to keep pathogens from entering the body easily. The immune system also consists of cells that are specialized in recognizing and destroying the pathogens that nevertheless make it through this barrier. So, you see, a horse with a good immune system is less susceptible to all types of infections and, if it does fall ill, will recover more quickly.

The gut as a driving force

What does the gut have to do with all this? The gut is the body’s largest immune organ. 80% of all immune cells, which recognize possible pathogens, are found in the gut. This also applies to more than half of all effector immune cells which subsequently respond to pathogens. “Good” bacteria, which exists in the gut naturally, have an important driving force; they are responsible for immune cell development. These gut bacteria can also steer the entire immune system in a certain direction, for example towards more tolerance or more defence.

Gut bacteria communicate directly with the immune system. They also produce substances that strike up dialogues. Healthy gut bacteria produce short chain

(NATURALLY) STRONG DEFENCES: A BRILLIANT SYSTEM

The immune system is influenced by many factors. The body is constantly fighting off intruders. This is the job of white blood cells. These may be viewed as soldiers protecting the body. Anything harmful that tries to get in, e.g., viruses, will be attacked by this army of white blood cells.

The immune system is made up of two lines of defence. The first is a nonspecific and innate immune system that spontaneously attacks and destroys all invaders (penetrating pathogens). This defence is based on tissues that come into direct contact with the outside world, such as skin and mucous membranes. If a pathogen survives this first attack, it then faces the second line of defence. This involves a more specific defence mechanism which, with the help of antibodies, hunts down certain invaders. In contrast to the “soldiers” of the nonspecific immune system which attack all foreign cells, antibodies are specialized trackers tasked with the mission of destroying a certain invader. Antibodies are also stored in the body. They are quite adept at spotting their “enemies”, remembering them in order to make short work of the same invader the next time it comes calling. Vaccines, for example, provide long-term protection against certain viruses. The more antibodies present, the more virus particles the immune system recognizes and the harder it becomes for the virus to penetrate the cells. Which makes sense; the better shape your army is in, the less chance invaders have to make your horse ill. Keeping this army in top form occurs through good gut health (where 80% of all immune cells are found) and reduction of stress. A horse’s immune system relies on a healthy diet along with regular and frequent rest periods to function well.

fatty acids like acetic acid, propionic acid, and butyric acid. These short chain fatty acids strengthen gut health and increase the amounts of certain substances that stimulate the immune cells to enter the gut. They are also absorbed into the bloodstream so that their effects are distributed throughout the entire body. Tests have shown that this leads to improved natural defences in the lung and spleen. So, a healthy gut microbiome can improve the natural defences of the respiratory tract. That may sound strange, but it’s true! Naturally, the gut is also tasked with the absorption of nutrients. Along with energy, the cells of the immune system also need amino acids from proteins to produce antibodies. This production process also requires vitamins and minerals to act as catalysts.

Good health from within

So, it’s clear that a healthy gut microbiome is important for a strong immune system. But how can you help your horse to have a healthy gut? Unfortunately, there’s no magic feed or supplement for this – the answer is looking at the big picture. Make sure your horse has plenty of available forage, such as grass, hay, haylage, lucerne, or beet pulp. The good bacteria will thrive and produce short chain fatty acids, the best source of energy for your horse. However, forage alone won’t cover all of your horse’s nutritional requirements. Always make sure that your horse gets enough vitamins and minerals in the form of a concentrate, feed supplement, and/or a forage balancer. If your hay is poor quality, your horse may not be getting enough protein, which means you should supplement his feed ration. Is your horse going through a difficult phase and you’d like to give him some extra help? Then you can give him extra Omega-3 fatty acids.