The role of the lymphatic system in energy metabolism

Article by Peter Bollen, head nutritionist Cavalor

In recent years, focus has turned towards the emerging science of the lymphatic system. It is as important as the circulatory system (which includes the heart and the blood vessels), and is fundamental to the functioning of the body and central to the immune system, energy metabolism, detoxification and energy availability in the horse’s body.

A horse with a well-functioning lymphatic system can metabolise energy and clear metabolic waste more efficiently, leading to enhanced performance and faster recovery. 

So how can we tap into the benefits of an effective lymphatic system? Well, the first step is in understanding what it is. We might know that nutrients and oxygen are carried in the bloodstream towards our tissues, but what about how they are actually delivered to the cells?

This is where the lymphatic system comes in. Broadly speaking, it runs in parallel to the circulatory system and creates the point of delivery to the cells and tissues. The circulatory system carries the blood via arteries and vessels, which get smaller as they reach the muscle tissue as capillaries - where the wall is only one cell thick.  

This enables smaller molecules such as nutrients and oxygen to be pushed out of the capillaries and into the fluid around the cells - or lymph - while retaining larger cells like erythrocytes (red blood cells). 

The lymphatic system is an extensive network of vessels and nodes that transports lymphatic fluid around the body and it has two main functions:

1. Energy metabolism - transporting nutrients and oxygen to the cells

All the cells and tissues of a horse’s body are surrounded by a watery gel-like substance called interstitial fluid. This provides a medium for dissolved oxygen and nutrients to travel across to the cells. Lymph capillaries, carrying these substances, run through the interstitial fluid. The walls of these capillaries are also only one cell thick and have overlapping junctions, which make them highly permeable and allow easy transfer of materials.

In practical terms, this means the horse’s muscles and tissues get all the energy they require to carry out all their metabolic processes. As well as being responsible for giving cells the oxygen and nutrients they need, the interstitial fluid transports salts, hormones, neurotransmitters, coenzymes, amino acids, sugars and fatty acids around the body via the lymphatic system.

“A horse with a well-functioning lymphatic system can benefit from increased energy and enhanced performance, but without feeling too fresh or fizzy”

2. Detoxification: processing waste products

During the season, horses are placed under physiological demands and their body has a lot to process. In hard exercise and in races, their body will produce a lot of waste products. Their thin-walled lymph vessels also allow interstitial fluid into them to remove the waste products of cell metabolism (such as cell debris, bacteria, dead blood cells, pathogens, toxins, lactic acid and protein molecules) from each cell. This process is just as important as carrying necessary materials to the tissues to provide energy. 

These metabolic waste products are carried in the lymph away from the cells for detoxification. This is the term used for the continuous processes in the horse’s body to remove those waste products or metabolites that are naturally produced.

Detoxification takes place mainly in the liver, kidneys and intestines, so it is really important to ensure that those organs in the horse are healthy and functioning well. By supporting the liver and kidneys, you can help this breakdown process and allow the horse to better metabolise compounds that would otherwise be toxic if they remained in the body.

Gut health is also very important to the lymphatic system and detoxification, given that more than half of the lymphatic vessels of the horse are located within the gastrointestinal tract. 

Peristalsis (the natural contraction and relaxation of the gut wall) drives the return of lymph to the rest of the body. Movement in the gut is stimulated by food consumption (mainly long fibres) and is crucial to lymphatic system function as there is very limited muscular contraction in the horse’s lymphatic vessels themselves. This means it relies on passive forces from movement of other systems in the horse’s body as opposed to active muscle contractions.

Ensuring sufficient feed for a horse around the clock is crucial, not only for maintaining gut health, but to maintain a healthy immune system and detoxification process as well.

Lymphatic system and immune function

In addition to lymph and lymph vessels, the horse has around 8000 lymph nodes. These bundles of lymphoid tissue and proteins act as a filter for foreign substances that travel through the lymphatic fluid and contain lymphocytes (white blood cells) that help the body fight infection and disease. This means that the lymphatic system is also key to the functioning of the immune system.

As the lymph tissue approaches each lymph node, it slows down and collects in that area. Horses have so many lymph nodes that they are extremely susceptible to lymph node blockage. Lymph nodes can actually be felt or sometimes seen at various points around the horse’s body, particularly around the head and neck or when they are swollen.

Keep on moving

Movement is so important for horses, precisely because of the fact that there are no direct muscular contractions within the walls of the lymph vessels to promote the flow of lymph. The functioning of their lymphatic system relies on the force of movement of other structures in the body, such as the movement of the skin to apply pressure to the underlying tissues and stimulate the transport of lymph through the vessels.

In the modern day, racehorses can be stabled for longer periods of time. It is very common to see leg swelling, which has a very simple explanation in terms of the immune system. This principle of continuous movement being necessary applies especially to the legs, where this elastic movement of the skin is assisted by a pump mechanism in the hoof and fetlock joint. It is thought that this is the case due to there being no muscles in the lower limbs of the horse to aid the movement of lymph from this area.

Horses therefore need to move extensively and perhaps almost constantly (up to 16 hours per day) to keep the lymph circulating around the body, and standing still for too long significantly impairs the functioning of the lymphatic system.

Practical tips for a healthy lymphatic system

1. Turn horses out as much as possible  

Horses that are standing still for long periods of time are at risk of an impaired lymphatic system, which can impact the immune system, recovery time and ultimately performance. Turnout makes a happier horse and a healthier horse.

2. Cool down for at least 15 minutes after exercise

The period of time immediately after training is important for removal of metabolic waste products and keeping a horse moving after a hard training session stimulates the lymphatic system to continue to remove waste products from cells, which includes the removal of lactic acid. By cooling down properly after every session, you can significantly improve recovery times.

3. Consider feeding supplements that can directly benefit the lymphatic system

Functional herbal ingredients in innovative supplements can support lymphatic system function. Cleavers (Galium aparine) is known to bring benefits to the lymphatic system. Couch grass (Elymus repens), Nettle (Urtica dioica), and Dandelion (Taraxacum officinale) are all known to have purifying effects which can support metabolism and detoxification.

Even Lionel Messi, Usain Bolt or Iga Swiatek have picked up issues through their sporting careers, despite having elite support teams behind them. Unfortunately injuries do just happen, but with foresight, preparation and providing the best nutritional support to their horses, trainers will give themselves the greatest chance of avoiding yet another bad news phone call to an owner.

Always read the label – experts guide us through equine healthcare products

By Lissa Oliver

We all want what’s best for our horse and we are happy to pay a price for the benefit of a happy, healthy and peak-performing horse. But what if that price is a hefty fine, suspension or even serious health consequences for us and our staff? How much trust can we afford to place in the claims of manufacturers, and do we pay enough attention to instructions? 

Ultimately, the responsibility for what goes into our horses lies fully with us. In this article, we’ll focus on the nutritional product labelling as well regulation of products which are promoted to consumers.

Nutrition

Dr Corinne Hills is an equine veterinarian with more than 20 years’ experience in practice in Canada, the Middle East, Europe, New Zealand and Australia, leading her to develop Pro-Dosa BOOST, manufactured from her own purpose-built, GMP-registered laboratory in New Zealand. 

Ingredient listings 

“We all want to make good choices and support our horses in the best way we can, with the best use of our finances,” Dr Hills agrees. “Horsemen always ask me about ingredients, but nobody ever asks about quality management. Similar products might appear to contain the same ingredients, but if the quality of the ingredients is poor, they will provide no benefit. Think about what you are spending your money on, and learn to read labels critically.

“It’s important to know the nutrient content of your feed and forage. In a perfect world everyone would consult their nutritionist and have forage tested, knowing exactly what their horse requires, what it is receiving and what supplements, if any, are needed. Horsemen don’t always feed a ready-prepared balanced feed. If they are mixing their own, they should be analysing the components of their feed. It’s easy and inexpensive, and your vet will know where you can send samples for analysis. Good feed companies provide the service for free. 

“Simply reading the label of feed and supplements could save you quite a bit of money. In my experience most people way over-supplement. A balanced feed manufactured by a reputable company should provide all of a horse’s requirements. Adding supplements could disturb the balance of the nutrients being fed. It is worth taking the time to understand nutrition to effectively support equine health. You can go to your feed company and ask their in-house nutritionist to suggest a tailored balanced diet that will suit most horses in your stable. If the feed company doesn’t have a nutritionist, it might be worth looking around for a new feed supply.

“Metabolism is quite complex, requiring a broad range of essential nutrients to function optimally. A lot of one nutrient doesn’t make up for deficiencies in another. The balance between nutrients is important. Some nutrients are required for the uptake and function of other nutrients. Too much or too little of one nutrient may result in deficiencies or toxicities of other nutrients. Imbalances can adversely affect health, performance and recovery. At a minimum, imbalances in a feed or supplement can render a product ineffective.

“For instance, vitamin C is required for the absorption of iron from the gut. Without vitamin C, iron passes straight through the gut and out in the faeces. Vitamin E, on the other hand, has a negative interaction with iron. It binds with iron and reduces its absorption, causing much of it to be wasted. So, in order for horses to use dietary iron effectively, it must be administered with vitamin C and without vitamin E. Iron balance is also closely related to zinc, manganese, cobalt, and copper.”

Nutrients Ratio

Ca:P 1-2:1

Zn:Mn 0.7-1.1

Zn:Cu 3-4:1

Fe:Cu 4:1

“B vitamins are known to work better when administered in optimal balance with each other. Amino acids are another good example of how nutrient balance is important. The balance of amino acids in a feed is as important as the amount of protein. Imbalances in amino acids limit the amount of protein in a feed that is usable in the horse to produce proteins and muscle cells, and the wasted amino acids that can’t be used for protein synthesis create a load on kidneys, elevate body temperature and elevate heart rates.

“It is also important to adhere to the instructions on the label. If insufficient doses are given, then no impact or a negative impact on the overall health of horses may result. 

“If you are buying a supplement that doesn’t contain what the label says, then at best, it’s a waste of money. At worst, it could be detrimental to your horses’ health. Giving too much of some nutrients is dangerous.”

Reading the label isn’t always an easy fix, however, as Dr Hills points out.

“Standing in a feed store, I couldn’t easily choose a good one as I couldn’t work out what was in each one by just looking at the labels. I had to photograph the labels and then put the information into a spreadsheet, convert all the quantities and units to a single standard, and then compare those contents to equine nutrient requirements. 

“How many horsemen do that? And if they don’t know what they are feeding their horses, aren’t they worried?”

Dr Hills has one simple tip. “If labels are easy to understand so that you can tell at a glance what you are giving your horse, then the manufacturer is probably proud of their formulation and believe it will stand up to scrutiny.

“If you have to perform too many calculations to figure out what you are giving, there is a fair chance that the formulation isn’t great. Some companies don’t actually want you to know how much or little of each nutrient is in their product. Take the time to do the maths and make sure you are making a true comparison before picking the cheapest or prettiest product on the shelf.

“When reading labels, it is important to consider all aspects of the nutrient composition—including balance, form and dose—in relation to the nutrient requirements of your horse.

“I found a huge number of products listing different combinations of nutrients that were included in different forms. For example, calcium could be provided as calcium carbonate, tricalcium phosphate, or calcium gluconate. They were also quantified with different units of measure, such as mg/kg, %, ppm, to name only a few. Then, they were to be given in different doses.

“The most confusing paste I found listed contents in terms of parts per million (ppm), percentages, and mg/kg. Then, the syringe was in pounds and the recommended dose in ounces.”

Quality control

“How do you know if a product is manufactured safely and meets label claims?” Dr Hills asks. “This information frequently isn’t on the label, but it’s just as important as the ingredients list; so it’s well worthwhile to make the effort to source the information. 

“You could look for a statement on the website about quality management, or you might have to ask the manufacturer some questions. Does the manufacturer have a quality management programme? GMP or ISO certification provides hard evidence of this.

“Be sure to ask every rep that visits your stable about quality management as they will almost certainly be the most readily available source for this information. Any rep that can’t talk competently about their company’s quality management programme probably represents a company that doesn’t have one.

“GMP stands for Good Manufacturing Practice, and this is a specific standard required for pharmaceutical producers. It is, however, voluntary for feed supplement manufacturers. A generic version of good manufacturing practice, abbreviated with small “gmp,” is a reference to a quality management system that is not government specified and inspected. It could be the same as GMP or it could be applied to a non-standardised or less complete quality system.

“If a company has either ISO or GMP certification, you can be sure that the supplements they produce will be safe, secure and generally meet label claims.

“Once you have selected a good quality, safe and healthy feed, then you can probably feed it to most of the horses at your stable. Spelling horses and smaller horses will need to eat less of it with more hay or grass. Racehorses or broodmares will need to eat more of it.”

Veterinary Medicines Directorate

The Veterinary Medicines Directorate (VMD) is the regulator of veterinary medicines in the UK. Louise Vodden and James Freer, from the Enforcement Department of the VMD, guide us through the draft documentation outlining the legislation behind the manufacture, sale and labelling of equine health and welfare products.

Guidance for advertising non-medicinal veterinary products

When advertising a non-medicinal veterinary product, it must not, by presentation or claims, suggest that it is medicinal. 

This applies to any advert—be it in magazines, online, at trade events or through client meetings and listing materials—that is aimed in part or in full at a UK audience. It is the responsibility of anyone engaged in marketing activities to comply with the VMD.

A veterinary medicinal product is legally defined as:

• Any substance or combination of substances presented as having properties for treating or preventing disease in animals.

• Any substance or combination of substances that may be used in, or administered to, animals with a view either to restoring, correcting or modifying physiological functions by exerting a pharmacological, immunological or metabolic action, or to making a medical diagnosis.

Medicinal by presentation

The first part of the definition above covers products that indicate they have a beneficial effect on an animal’s state of health. This is known as “medicinal by presentation”.

Prevention

This includes the destruction of parasitic infestations on an animal that may cause a medical condition, such as flea allergic dermatitis; hence, products that kill fleas on an animal are also classified as medicines.

Disease

This is considered to cover a broad range of conditions ranging from those caused by bacterial, viral or parasitic infections, to disorders resulting from various systemic dysfunctions, or deficiencies of substances essential for survival. We generally use the catch-all term “adverse health condition” for something wrong with an animal’s state of health. This includes injuries that pose a significant risk to wellbeing or would require more than the most superficial of management.

Medicinal by function

The second part of the definition covers two further aspects. The first relates to products containing substances with a recognised medicinal effect, commonly referred to as “medicinal by function”. The second covers the purpose of putting something in, or on, an animal to effect a change (restoring, correcting, modifying) in the way a bodily system works.

Restoring

This covers claims of restoration of function in any system within an animal that, for any reason, is not functioning within the normal range for an animal of good health. Even if there is no claim, be careful not to present before and after treatment expectations in your advert. For example, in one picture the dog can barely walk, and in another the same dog scampering along apparently healed. Such an advert would be considered medicinal by presentation.

Correcting

This covers any product used to address any deficiency or dysfunction in an animal’s systems. This includes issues like nutritional deficiencies in an animal, hormone imbalances, immunomodulation to address allergic reactions and correction of digestive dysfunction.

Modification

This includes any effect that changes the way an animal functions that is not covered by restoration or correction effects. In most cases, these tend to be enhancement claims such as “boosting”, “better”, “stronger”. Where such claims are made, the immediate question is, “better than what?” If the answer is, “better than normal,” then the product is considered medicinal by presentation. If the answer is, “better than an animal with condition X,” then it is considered as claiming to be medicinal by function.

Making medicinal claims

Non-medicinal products cannot claim to treat, prevent or control any adverse health condition. Nor can it refer, expressed or implied, to the treatment or prevention of a disease or adverse condition, or to improving the state of health of the animal treated.

For example, medicinal claims include a reference to the treatment or prevention of scours, colic, footrot, laminitis, sweet itch or pathological nervous conditions—or any other condition which is not the normal state of a healthy animal. This includes references to symptoms or any indication that the product is for use in an animal which is not in a normal healthy state.

References to the nutritional maintenance of a healthy animal, healthy digestive system or healthy respiratory system would not normally be regarded as medicinal claims. Though this does not extend to claims for preventing the occurrence of an adverse health condition or its symptoms.

Any implication that the product for use in an unhealthy animal and is intended for purpose of, or has the consequential outcome of, preventing a detrimental health state in an animal would predispose the product for a medicinal purpose for which it would require a marketing authorisation. Exceptions to this include particular nutritional purpose feeds, however, there are also specific restrictions on the claims these products can make.

Things to avoid in the advertising of non-medicinal products

• These products can only be presented for the maintenance of health in healthy animals.

The basic premise is that the purchaser of the product has a healthy animal and will be using it to support their animal’s state of health. Health maintenance does not include attempting to halt or slow the progression of a detrimental health state.

• Association with an adverse health condition

Narratives may not be used to suggest some terrible disease will or may happen, nor using statements like “4 out of 5 get” to present the product as the solution. This is considered a medicinal claim. Occasionally this approach is prefaced with the overtly medicinal company statement of intent that “we believe prevention is better than cure”.

Reference to specific diseases may be made in the form of a safety warning where use of the product may pose a risk, for example “WARNING: Not to be fed to horses with PPID”.

• Comparisons and presentation of equivalency to authorised medicines

A product not authorised as a veterinary medicine must never be presented, in any capacity, in comparison to any form of authorised medication. Marketing material for a non-medicinal product must not indicate or imply that the product can, or is intended to, be used as a substitute for authorised veterinary medicines. Nor should the use of a non-medicinal product be presented as resulting in the reduction of the use of any authorised medication. To do so is considered a medicinal claim for the product.

Disclaimers do not provide a remedy to the misrepresentation of a product in a medicinal capacity.

• Testimonials, quotes and endorsements

If customer testimonials are used in connection with the marketing of a product and report results containing medicinal claims, the claims will be regarded as those of the company marketing the product.

Claims made by a third party, such as magazine reviews or articles published by independent analysts, will be regarded as those of the company marketing the product where evidence confirms that the third party has a connection to the marketing company via solicitation, endorsement, sponsorship or funding.

If, for example, a vet who has been using a product for years expresses an opinion that is not being given in support of marketing a product, then it would just be an opinion. Any material published in support of marketing the product is considered to be marketing material. Whether that material is based on professional opinion, peer review studies, customer feedback, folkloric tradition or an “everybody knows”claim is not relevant. It must still adhere to the rules governing marketing material.

Herbal or “natural” products

Herbal products, “nutraceuticals”, or any products sourced in a way generally described as “natural” are treated like any other products. A natural origin provides no exemption from these requirements; they require authorisation if they are medicinal by function or presentation.

Biocides, insecticides and repellents

The following are always medicinal products requiring a marketing authorisation due to their use on animals:

• Veterinary product that contains substances that kill insects or external parasites (e.g., pyrethrins, pyrethroids or organophosphate compounds) as they are medicinal by function

• Veterinary product claiming to have, or which has, the function and  control of internal parasites

• Veterinary product claiming to treat or prevent a disease caused by a viral, bacterial or fungal infection

The following do not require an authorisation, provided they do not claim to treat or prevent disease:

• Product containing a repellent, such as diethyltoluamide or ethylhexanediol, provided it claims only to repel external insects

• Product applied only to housing or bedding

• Topical disinfectant applied to intact skin provided it does not claim to treat or prevent disease, including infection prevention (e.g., shampoos)

The marketing of these products is covered by legislation on biocides.

For further information regarding non-medicinal products, email enforcement@vmd.gov.uk or call +44 (0) 1932 338308 or +44 (0) 1932 338410

Probiotics – The key to a well-balanced equine gut

By Kerrie Kavanagh

It is no surprise that the health maintenance of the racehorse is a top priority for trainers. And probiotics can be used as a treatment modality to manipulate the gut microbiome to improve or maintain health. Equine studies to date have shown that probiotic strains can offer an advantageous approach to minimising disturbances in the gut microbial populations, repair these deficiencies—should they occur—and re-establish the protective role of the healthy gut microbiome. Other probiotic-associated health benefits include reducing diet-related diseases such as colic and laminitis, preventing diarrhoea, conferring host resistance to helminth infection, improving stress-related behavioural traits (e.g., locomotion) and even promote the development of an effective gut-brain communication pathway. 

Probiotics have been used by humans for more than 5,000 years with their development closely linked to that of dairy products and fermented foods. Today, probiotics are seen as an excellent non-pharmaceutical way to improve the health of both humans and animals, and there are a plethora of products to choose from. But what exactly is a probiotic, and how do they work? Why would your horse need one? What types of probiotics are available for horses? These are all questions that horse trainers ask frequently, which we will attempt to answer here. 

The Equine Gut Microbiome

Probiotics and the equine microbiome can benefit from a valuable symbiotic relationship; probiotics are seen as a restorative treatment modality for the gut, to re-establish the bacterial populations there and also to re-establish the protective role that the health gut microbiome confers to the host. But when we discuss the equine microbiome, what are we really talking about? 

The gut microbiota/microbiome can be categorised by anatomical location such as the oral microbiota/microbiome in the mouth and the intestinal microbiota/microbiome in the intestines, etc. Therefore, the gut microbiome pertains to the microbiota in the gastrointestinal tract. This population of microorganisms (bacteria, fungi, viruses, protozoa) is referred to as the ‘microbiota’ of the gut, while the term ‘gut microbiome’ refers to the genetic material associated with these microorganisms. The microbiome can be defined as the sum of the microbes and their genomic elements in a particular environment. If we look at the definition of the microbiome having the propensity to an equation, then any equation must be balanced; to maintain that balance is key. If the microbial community exists in an environment in a balanced state, then any upset or disturbance to the microbial populations will cause the balance to shift (known as dysbiosis). To maintain the balance, we need to firstly understand the way the microorganisms exist within their community (i.e. their microorganism-to-microorganism interactions and also microorganism-to-environment interactions) and secondly, their functioning role. If we can understand their (microorganism) position and role, then we can maintain the balance or re-establish the balance if a shift occurs.  

Fig. 1 Factors that can lead to gut Dysbiosis

The human intestinal microbiome is now recognised as an organ and likewise, the equine intestinal microbiome is deemed an ‘organ’ of the body and is vital for the breakdown of complex food and subsequent release of energy, protection against the pathogenic bacterial colonisation and in regulating the immune system and metabolic functions. There has been much debate regarding the content of the healthy equine microbiome, and even to deduce what ‘healthy’ or ‘normal’ is requires a level of understanding of the microbiota associated with healthy horses. This question has been posed by many researchers and frankly has yet to be answered with certainty. There are many reasons why the ‘normal’ microbiota keeps eluding us; and this can be attributed to the many reasons as to why the gut microbiota (of a healthy horse) can be affected (see Figure 1). It is thought that the diversity of the human gut microbiota and the general assembly of microbial communities within the gut (with the dominant phyla being classed as belonging to Firmicutes and Bacteroidetes) is a shared hypothesis across most species (i.e., humans and animals share a similar gut microbiome structure). Firmicutes and Bacteroidetes have been shown to constitute the main dominant phyla in equine, bovine, canine and feline gut microbiome studies indicating the cruciality of the role they play in the maintenance of a healthy microbial ecology in the gastrointestinal tract. Several studies do agree that dominant phyla of the equine gut microbiota are obligate anaerobes: the gram-positive Firmicutes and the gram-negative Bacteroidetes; other phyla are identified as Proteobacteria, Verrucomicrobia, Actinobacteria, Euryarchaeota, Fibrobacteres and Spirochaetes. Ninety-five percent of the  Firmicutes phyla contains the Clostridia genus in addition to genera related to gut health such as Lachnospiraceae, Faecalibacterium and Ruminococcaceae. The other main dominant phyla, Bacteroidetes, on the other hand contains a large variety of the genus. 

Role of the Equine Gut Microbiota

The role of the gut intestinal microbiota serves to protect and prevent disease. The gut microbiota has several purposes: prevention of pathogen colonisation by competing for nutrients, enrichment and maintenance of the intestinal barrier—their ability to renew gut epithelial cells and repair damage to the mucosal barrier, the breakdown of food and releasing energy and nutrients, such as synthesising vitamins D and K and also conserving and restoration of the immune system by the formation of antimicrobial metabolites and blocking access to the binding sites of the mucosal wall. The gut microbiota is also thought to play some role of influencing the neuro-active pathways that affect behaviour. It is not surprising to see that gut disorders and gastrointestinal diseases can arise when gut dysbiosis occurs. The role of the gut microbiota may have even more importance than is realised and may have a role to play with developing illness or disease later in life.

The microbial colonisation of the intestinal tract begins at birth. The foal begins its colonisation through contact with the microbiota of the mare’s vaginal and skin surfaces plus the surrounding environments to which the foal is exposed and reaches a relatively stable population by approximately 60 days in age. It is perhaps a fight for dominance to achieve establishment in the gut among the bacterial populations that sees the foal’s microbiota as being more diverse and quick to change when compared to that of the older horse. The subsequent colonisation of the intestinal tract will reflect the foal’s diet, changing environment, introduction to other animals, ageing and health.

What exactly is a probiotic?

Beneficial bacteria can be isolated and harvested to prepare a bespoke probiotc

The word ‘probiotic’ is of Greek origin meaning ‘for life’ and the WHO/FAO have defined probiotics as ‘live microorganisms which when administered in adequate amounts confer a health benefit on the host’.  People have long believed that exposure to non-pathogenic microorganisms can benefit the health of humans and animals. The thinking behind this is that daily consumption of sufficient numbers of ‘good’ microorganisms (either bacteria or fungi) can maintain a healthy population of microorganisms in the gut and benefit overall health.  

Probiotics are used to manipulate the bacterial populations of the gut in order to re-establish the delicate microbial balance there which, in turn, confers health benefits on the host. As the benefits associated with some of the ‘good’ bacteria within the gut became known, these were referred to as probiotic bacteria. 

How do probiotics work?

There are 4 main mechanisms by which probiotics are thought to exert their effects.

1. By inhibiting pathogen colonisation in the gut through the production of antimicrobial metabolites or by competitive exclusion; in other words, they prevent the ‘bad’ bacteria from growing in the gut.

2. By protecting or re-stabilising the commensal gut microbiota, probiotics can be a means to re-establish the balance of the gut microbial populations.

3. By protecting the intestinal epithelial barrier, they maintain the health of the intestinal wall.

4. By inducing an immune response, probiotics can boost the immune response and help prevent disease.

If we consider the definition of a probiotic as ‘live non-pathogenic microorganisms that, when administered in adequate amounts, confer a health benefit on the host’, then this reference to ‘adequate amounts’ must be emphasised, and the dose administered is critical to ensure that the probiotic has the desired effect. For horses, we must consider the route through the digestive tract that the probiotic strains must travel to arrive at their destination is a distance over 15 metres long. It is a race for survival! The gastrointestinal system has many obstacles along the passage such as the acidic stomach environment and the dangers of exposure to bile and digestive enzymes, in which they must survive. The initial dose of ‘live’ probiotic strains is therefore crucial to ensure survival in the gut. Prebiotics are ingredients such as carbohydrates and fibre, which promote the growth of these probiotic bacterial/yeast strains in the gut. Prebiotics are essentially the food for the probiotic strains and can help form a symbiotic relationship with the probiotic to improve the overall health status of the horse. 

Why would you need to give your horse a probiotic?

Gut dysbiosis is a fluctuation or disturbance in the population of microorganisms of the gut, which may be linked to a wide range of diseases in horses. Gut dysbiosis can be caused by many factors ranging from dietary changes, antibiotics, disease, intense exercise and training, age, worms, environment, travel, or even minor stress events—resulting in major consequences such as colic. Dysbiosis is generally associated with a reduction in microbial species diversity. 

Diet is one of the major factors contributing to gut dysbiosis. Unlike the ruminant cattle and sheep that use foregut fermentation, horses are hindgut fermenters. The large intestine is the main area where fermentation occurs. The horse utilises the microbial enzymes of the hindgut microbial population in the colon and caecum to break down the plant fibres (cellulose fermentation) sourced mainly from grasses and hay. The horse itself does not possess the hydrolytic enzymes that are required to break the bonds of the complex structures of the plant carbohydrates (in the form of celluloses, hemicelluloses, pectins) and starch; so therefore, it strongly relies on the microbiota present to provide those critical enzymes required for digestion. The main phyla Firmicutes and Bacteroidetes possess enzymes capable of breaking down the complex carbohydrates (such as starch and cellulose). Research has shown that forage-based diets (grasses and hay) promote the most stable gut microbiomes, but ultimately the equine athlete requires far more energy than a forage-based diet can supply. Supplementing the diet with concentrates containing starch such as grain, corn, barley and oats can affect the number and type of bacteria in the gut. Optimising diet composition is so important as carbohydrate overload—as seen with high-starch diets (>1g/kg body weight per meal)—can change the populations of bacteria in the gut, alter pH, upset digestion and the gut environment, and ultimately result in diseases such as colitis, colic and laminitis. The correct diet is essential for maintaining the delicate balance of bacterial populations. Probiotics can be used to either replace the bacteria missing in the gut and/or can help maintain the delicate microbial balance even in the face of adversity such as abrupt dietary changes, antibiotic treatment and stress.

What types of probiotics are available for horses?

There are several probiotic products on the market, and most are in powder or liquid form. There are two main categories of probiotics: generic and autogenous. Generic probiotics are off-the-shelf products that contain specific strains of bacterial or yeast, singularly or in combination. The Lactobacillus and Bifidobacterium families, Enterococci and yeasts such as Saccharomyces cerevisae and boulardii are the most common equine probiotic strains. Advantages of generic probiotics are that they are widely available, easy to administer, and they may be beneficial to horse health (if the strains are alive in sufficient numbers). Autogenous probiotics are specifically formulated using bacteria obtained from the horse’s own faecal sample and, as such, are uniquely adapted to that individual animal. These host-adapted bacteria are more likely to survive in the gut than non-adapted generic strains and can quickly replenish absent or low levels of bacteria unique to the individual horse, thus maintaining health.

Can nutrition influence EIPH? -Catherine Rudenko investigates alternative and supportive therapies as trainers seek to find other means of reducing the risk or severity of EIPH

By Catherine Rudenko

EIPH (exercise-induced pulmonary haemorrhage) was first identified in racehorses in the 16th century. Since this time, the focus has been on mitigating the haemorrhage. Management of EIPH largely revolves around the use of furosemide, dependent of jurisdiction, may or may not be used on the day of racing. Alternative and supportive therapies are becoming increasingly popular as trainers seek to find other means of reducing the risk or severity of EIPH.

Nutrition and plant-based approaches are part of an alternative management program. Whilst research is somewhat limited, the studies available are promising, and no doubt more work will be done as using furosemide becomes more restricted. There are several directions in which nutrition can influence risk for EIPH, including inflammatory response, blood coagulation, cell membrane structure, hypotension and reducing known lung irritants.

Exercise- induced injury may exacerbate the severity of EIPH as a result of the delayed sealing of damaged micro vessels.

The various approaches are all supportive, working on altering an element of risk associated with the condition. Some are more direct than others, focusing on the effect on red blood cells, whilst others work on some of the broader lung health issues such as reducing mucus or environmental irritants. 

None are competitive with each other, and there may be an advantage to a ‘cocktail’ approach where more than one mode of action is employed. This is a common practice with herbal-based supplements where the interactive effects between herbs are known to improve efficacy. 

Cell membrane

The red blood cell membrane—the semipermeable layer surrounding the cell—is made up of lipids and proteins. The makeup of this membrane, particularly the lipid fraction, appears to be modifiable in response to dietary fatty acids. Researchers feeding 50mls of fish oil found a significant increase in the percentage of omega-3’s in the cell membrane.

Essential fatty acids (EFA’s), omega 3 and omega 6, are important cell membrane components and determine cellular membrane fluidity. Fluidity of a cell membrane is important, particularly when pressure increases, as a cell membrane lacking in fluidity is more likely to break. A cell that can deform, effectively changing rather than breaking, has an advantage and is linked with improved exercise performance in human studies. Inclusion of fish oil in the diet increases the ability of red blood cells to deform.

Kansas State University investigated the effect of omega supplementation on 10 thoroughbreds over a five-month period. The diet was supplemented with either EPA and DHA combined, or DHA on its own. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are specific forms of omega-3 fatty acids commonly found in oily fish. When supplementing the diet with both EPA and DHA, a reduction in EIPH was seen at 83 days and again at 145 days. Feeding DHA on its own did not produce an effect.

Fish oil contains both EPA and DHA and is readily available, although the smell can be off-putting to both horse and human. There are flavoured fish oils specifically designed for use in horses that overcome the aroma challenge and have good palatability. 

Inflammatory response and oxidative stress

Airway inflammation and the management of this inflammatory process is believed to be another pathway in which EIPH can be reduced. Omega-3 fatty acids are well evidenced for their effect in regulation of inflammation, and this mode of action along with effect on cell membrane fluidity is likely part of the positive result found by Kansas State University. 

Kentucky Equine Research has investigated the effect of a specific fish oil on inflammatory response with horses in training. The study supplemented test horses with 60mls per day and found a significant effect on level of inflammation and GGT (serum gamma-glutamyl transferase). GGT is an enzyme that breaks down glutathione, an important antioxidant. As GGT rises, less glutathione is available to neutralise damaging free radicals, creating an environment for oxidative stress.

Kentucky Equine research results

A horse’s red blood cells are more susceptible to oxidative stress than humans, and maintaining a healthy antioxidant status is important for function and maintenance of cell integrity.

Rosehip

Supplements for bleeders will often contain relatively high doses of antioxidants such as vitamin C and vitamin E to support antioxidant status in the horse and reduce risk of damage to cell membranes. Vitamin C has also been shown to benefit horses with recurrent airway obstruction and increase antibody response. Dose rates required for an effect range from 15-20g per day. If including high doses of vitamin C in the diet, it is important to note that any sudden withdrawal can have negative effects. Gradual withdrawal is needed to allow the body’s own mechanisms for vitamin C production to recognise and respond to the change in status.

Rosehips are natural potent antioxidants containing many active substances. Research into the effect of rosehips specifically on red blood cells has shown they have a high efficacy when assessing their ability to ameliorate cell damage.

Hypotensive herbs

Caucus carota – wild carrott

The essential oil of caucus carota species is a well-documented oil having a hypotensive, lowering of blood pressure effect along with antifungal properties. Its antifungal effects are noted against aspergillus species, a common cause of poor respiratory health. Allium sativum is also well known for its ability to lower blood pressure. An initial study (data unpublished) into the effects of these two plants along with herbs reported to alleviate mucus in the lungs has shown promising results in a group of horses in training. 

Prolonged blood coagulation

As prolonged blood coagulation is cited as a possible factor for EIPH, herbal products that are noted for their ability to enhance coagulation are in certain parts of the world widely used as part of managing EIPH. …

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TopSpec - Trainer of the Quarter - Denis Hogan

By Breandán Ó hUallacháin

The TopSpec Trainer of the Quarter award has been won by Denis Hogan. Hogan will receive £1,000 worth of TopSpec feed, supplements and additives as well as a consultation with one of their senior nutritionists.

Denis Hogan was unsure what to expect when Sceptical, a £2,800 unraced purchase at the Horse-In-Training Sale at Doncaster in August 2019, joined him at his state of the art facilities last year. When asked how he approached the initial training of the gelding, Hogan said: “If we got a horse with form, we’d have something to go on, a line of ability, a rating probably, a distance that he races over, whereas when they’re unraced, we’re going off breeding and what they’re bred to do. Like most horses that have never raced, you build them up gradually. He then got a piece of work, and after a fast piece of work or two, we knew he was decent.” He concedes, however, that he wasn’t anxious when initially training the son of Exceed And Excel, knowing from Godolphin he had trouble breathing: “We knew he had issues, we knew his wind wasn’t perfect, but we’ve dealt with them (horses with wind problems) before.”

Though the gelding debuted on the all-weather at Dundalk on 30th October 2019, he had a wind operation after that run, with Hogan admitting “we got away with the first run.” The likeable handler states that the horse isn’t very difficult to train, describing him as “a joy to do anything with. On that score he’s 100% as good as you could ask for with temperament and attitude. His temperament, is absolutely brilliant, he’s so relaxed, calm. Nothing would phase him whatsoever, you could put him anywhere in any size of crowd, even travelling he never gets worked up. You could put him anywhere in a race – up front, out the back, in the middle.” Sceptical’s training routine has essentially remained the same since his arrival. It is quite simple; it doesn’t involve anything special, according to the Tipperary native, who is lucky to have access to a 5-furlong deep sand gallop and another gallop similar to Dundalk for his top charge. “We don’t over gallop him really, he’d be cantering away, and turn him out as much as we can; he might have a gallop at The Curragh or somewhere before a big race, but that would be it really.” Though Sceptical has run on both the all-weather and turf, his training doesn’t change much, irrespective of the surface he’s being prepared for: “No, not massively – much the same, only that the surface is different. I suppose he doesn’t need to be over the top fit for the all-weather, it’s an easy surface and horses skip off it – they tend to take the race quite well, not as hard as soft ground.”

While proudly conceding that he has many race options with a horse of this quality, the Cloughjordan man is cautious about asking too much of his stable star: “We have to be careful we pick the right races now and not over-race him. With a horse like this we have a couple of options, a few different plans. The Group 1 races are literally all overseas now, and right into the autumn, there are winter festivals in every corner of the world nowadays. I’d imagine he’d be kept busy.”

In citing the international success of his fellow county man, Tom Hogan, with the late Gordon Lord Byron, Denis Hogan may be considering some long haul flights for this laid-back individual: “Australia – there’s some big prize money down there, and he could be a candidate for the Breeders’ Cup, or the Prix de l’Abbaye, and Saudi has the big racing festival out there in February – there’s tonnes of options out there.”

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