It seems almost impossible to read news reports and social media posts these days without coming across someone telling you how important it is to look after your microbiome. From managing our mood and our weight, to reducing the risks of any number of diseases, someone, somewhere, will make a link to the billions of bacteria living in you, or on you.

But a recent study, published in the open-access journal Nature Scientific Reports, made a new and extraordinary connection: a foal’s internal hitchhikers may affect how fast he runs. And not just that – they can predispose to, or protect from, a range of conditions that might even prevent him from racing at all.

The paper followed 52 foals, born between February and May 2018, from five Thoroughbred stud farms in the UK. These foals were followed as they entered training (dispersed between 29 different training yards) and through to the end of their 3-year-old season.

In the earliest part of the study, faecal samples were obtained from each individual on day 2 postpartum and at regular intervals up until one year of age. These samples were then analysed and the number, variability, and different types of bacteria in the samples were assessed and recorded. The study was prompted by increasing evidence that not only are there a range of non-communicable diseases in humans affected by the bacteria within the intestines, but also that babies with differing birth and early-life circumstances may be predisposed to certain conditions, because of differences in their microbiome. 

The clinical and racing histories of the foals were then compared to the results of the microbiological evaluations. 

The results were striking: the gut bacterial community in the first months of life could predict the risks of specific diseases and athletic performance in later life. Foals with lower diversity (i.e. fewer different species of bacteria in their samples) at one-month-old had a significantly increased risk of respiratory disease in later life. A higher diversity was associated with a decreased risk of orthopaedic disease. And, when athletic performance was assessed — judged by comparing official ratings, number of starts/wins/places, and prize money earned — positive effects were again seen in foals with a greater diversity of bacteria at one-month-old and could even be linked to the relative abundance of specific bacterial families.

Foals are born without a functioning microbiome and must acquire all of their gut bacteria from their dam and their environment. This early phase of development, where foals are born with an immune system that is yet to encounter external challenges, is sometimes referred to as a ‘critical window’ — essentially a period when the gut microbial community imprints immunity and future health outcomes onto a blank canvas. There is now a great deal of interest in humans as to how this might be contributing to a variety of diseases: from obesity, diabetes and allergies, to diseases of the circulatory system, bones and neurodevelopment disorders such as autism. 

This particular study did not examine the gut microbial profile of the mares delivering and rearing the foals. But the authors point out that the gut bacterial profile of human mothers is known to be a primary driver of gut colonisation in human infants. Indeed, in human medicine, there is increasing engagement of methods to optimise this ‘handover period’ in neonates. There is limited evidence for how feeding mares may influence foals in this early phase. But a recent study, that fed two groups of mares on the same stud farm separate and distinct rations, demonstrated a stark difference in failure of passive transfer — assessed by levels of IgG in the foals’ blood within twenty-four hours of birth — between the two sets. Other researchers have confirmed that the microbial population of foals varies between stud farms, most likely due to differences in management styles. Numerous studies in other species have demonstrated links between maternal nutrition and various measures of colostrum quality, and there is evidence that a pro-inflammatory profile is seen in colostrum produced by obese mares, along with reduced medium-chain saturated fatty acid levels (important as an energy source and in the development of gut microbiota and immunity).

So, what if the balance could be tipped back in favour of the newborn foal, simply by adjusting how the mare is fed? And what if this could also affect the vigour of our young athletes? The developmental origin of health and disease (DOHaD) — first advocated by David Barker in the early 1990s — seeks to understand how exposure to environmental factors during periods of high plasticity in the early stages of life (including the gestational period) influences the program for development and disease risk in the progeny, that extends well into adult life.

Before the middle of the twentieth century, the foetus was believed to be immune from the effects of the maternal environment. It is now understood that in laboratory animals and humans, which is where of course almost all of this research has been done, numerous external factors influence the health and development of the foetus before birth. Historically, the focus has been on those causing adverse effects, such as polycyclic aromatic hydrocarbons — found in vehicle exhaust fumes and cigarette smoke — alcohol, and certain notorious pharmaceuticals. Epidemiogical studies began to link certain aspects of development, some not immediately obvious at birth, with environmental factors that had not been appreciated earlier and may be influenced by microbiome effects. For example, having “furry pets” at home impacts meconium bacterial diversity, and children reared with domestic animals from infancy have reduced prevalence of allergic-related diseases; maternal consumption of artificial sweeteners produces profound metabolic changes and microbiome changes in mouse pups (with profiles similar to those seen in human obesity). ‘Barker’s theory’ on the foetal origins of adult disease considered three characteristics: latency, where the effects may not be apparent until much later in life; persistency, in which conditions affecting the foetus continue; and genetic programming, where specific genes are switched on due to the prenatal environment. Brief windows at the very start of development, when a small number of cells are dividing rapidly and vulnerable to a range of influences, drive the development program of the entire individual, all the way through to adulthood.

Much of the work on the transferability of a healthy microbial population from one individual to another was prompted by early observations, reported in 1958, that patients affected by a particularly unpleasant and intractable cause of severe diarrhoea showed drastic improvements following a novel treatment. Clostridioides difficile is an anaerobic bacteria (it thrives in low-oxygen environments), commonly found in the intestinal tract of normal people. It doesn’t cause any issues until it proliferates uncontrollably, and the commonest reason for this is when the other bacteria in the intestine ecosystem are knocked out, usually by the patient receiving antibiotics for another problem. ‘C. diff’ is the commonest cause of antibiotic-associated diarrhoea, and it is notoriously difficult to treat in some cases — it only responds to a select group of antibiotics, many cases remain refractory, and it has a fatality rate of up to 40%. Back in the 1950s, the doctors were utilising a therapy that had been written about in the fourth century: transplanting gut bacteria from a healthy individual into the affected patient. And they did so by taking faeces from those healthy volunteers and delivering it via an enema (the very earliest records describe it being given as a ‘soup’).

Faecal microbiota transplantation (FMT) is now used in cases of C. diff that do not respond to first-line treatments and is well established for this, with impressive success rates of 80-90%. It works because it restores the normal balance of gut microbes, which prevents the Clostridia from maintaining a hold on the intestinal environment and, basically, out-competes them for the resources available. But as well as this, restoring the regular bacteria found in a healthy gut revitalises the relationship between the host —  us, or the animal — and the trillions of single cell organisms we live with.

Estimates of the numbers of bacteria within the body vary, but it’s safe to say it’s in the tens of trillions. It’s also safe to say that in most people the bacteria outnumber the human cells, in some cases by an order of magnitude. Whether the same is true of horses isn’t known, but considering the horse has evolved to rely almost entirely on bacterial activity within the intestine for its existence, it’s almost certain that the numbers involved are even more impressive. But the bacteria (and other microorganisms such as viruses and fungi) don’t just provide the necessary enzymes to digest food — they have evolved with the host and are absolutely vital for the development and maintenance of other functions, particularly the immune and nervous systems. Even within the intestine, it isn’t just a matter of dissolving the food as it passes through for the animal to absorb: the microbes are fundamental to those pathways developing adequately and operating effectively, from the earliest stages of life to the very last day of it.

The most striking examples of the absolutely cardinal role of bacteria in health and development can be seen in laboratory animals. Mice can be born and reared in sterile conditions, so that they develop without any (or very few) microbes in their environment and without the normal gut colonies they would usually possess. These so-called germ-free, gnotobiotic, or axenic mice do not develop normally. They can be fed the optimum diet and housed comfortably but they do not thrive: their immune and digestive systems are stunted, they do not gain weight normally, and they are vulnerable to a wide range of diseases. Even if introduced to ‘healthy’ microbial populations found in conventionally-reared animals they do not recover, most likely because they have missed the aforementioned, once-in-a-lifetime, critical window. Interestingly, germ-free mice can live longer than their colonised compatriots (if reared very carefully), which has recently raised important questions over the role of the microbiome in ageing and its implications for humans. 

Mammals need microbes. So where does a new-born mouse, human, or foal get these essential organisms from and, knowing what we know about the dangers that some types of bacteria present, how do they get the right ones?

It is now established that babies born via caesarian rather than vaginal delivery are more at risk from a number of conditions, including inflammatory and neurodevelopment disorders, and diseases of the bowel, lungs and joints, so much so that the technique of ‘vaginal seeding’ has become a much-discussed technique. Much of the impact of surgical delivery has been attributed to alterations in the microbial community that the infant is exposed to in the very earliest stages of neonatal life. While caesarian delivery is a very much rarer event in horses, the effect of early exposure to the ‘correct’ microbiome (sometimes referred to as ‘pioneer colonisers’) has been demonstrated in other species. The hygiene hypothesis is a term used to describe the way that early exposure to particular microorganisms is protective, and that a lack of such exposure leads to poor immune tolerance. Unfortunately, this term has sometimes been misunderstood: it doesn’t mean hygiene is a bad thing — we all need protection from pathogens — and it certainly doesn’t imply that having more infections during early life is advantageous. But a broad exposure to a variety of certain microbes is an essential part of development.  

But this exposure may begin even earlier. For many years, it was considered incontrovertible that the foetal environment in utero was sterile and that exposure to bacteria and other organisms only began at birth. However, recent work has challenged this ‘sterile womb paradigm’ and a number of studies have demonstrated the presence of microbial material within placental and foetal tissues. The debate is still ongoing, not least around whether the presence of bacterial DNA actually represents viable bacteria or simply fragments of long-deceased organisms; even the ability to breed axenic animals (as mentioned above) suggests foetal microbial colonisation is unlikely. 

What is emerging is a general consensus that the products of bacterial life in the mother may well be influencing foetal development, and could be crucial to it. Maternal microbiota produce bioactive metabolites that can enter the maternal circulation and may be actively or passively transferred through the placenta.

We know that elements of the microbiome that affect offspring are transferable: for example, bacteria taken from the gut contents of obese mice and transferred to pregnant, normal-weight mice, lead to overweight offspring with altered inflammatory responses. Maternal obesity causes changes in microbiota correlated with altered foetal brain development, while maternal undernutrition in humans affects infant immunity by attenuating responses to vaccines in early childhood (among many other effects). There is a huge volume of data concerning nutrition, and its effects on offspring, across many species, and it’s beyond the scope of this article to go into direct nutrient effects. Nonetheless, work has shown that foals born to obese mares are more likely to be affected by osteochondrosis, and supports the hypothesis that maternal relative hyperinsulinaemia may be a contributory factor through its role in cartilage differentiation. Foals born to overweight dams also have evidence of systemic inflammation (higher levels of plasma SAA) which may also affect development through inhibitory effects on bone growth. Crucially, the impact on progeny may be different depending on the alignment of the disturbance: i.e. whether the mares were obese at conception or overfed during the early or later stages of gestation. Maternal undernutrition is much less likely to be a problem in commercial breeding operations, but when it is, mares may develop a syndrome close to gestational diabetes in humans, a condition widely recognised to have potentially very serious consequences to the neonate, and even beyond. Again, timing is crucial: studies of epidemics, famine, and war show that mothers and their children have different outcomes depending on at which stage, from preconception to early childhood, the crisis occurred. 

Maternal stress during early pregnancy has been shown to reduce faecal bacterial diversity and alter taxa composition in pregnant mice and has been replicated in human studies. Conversely, severe maternal stress in the last trimester was associated with increased bacterial diversity in newborn babies. Maternal depression may alter the ratio of certain bacterial families in neonates, specifically by reducing numbers of Proteobacteria, a pioneer taxon which creates the environment for later anaerobic colonisation. 

A number of studies have identified known risk factors for infant severe respiratory tract infections, the leading cause of child mortality globally, including a carbohydrate-rich, fruit-/fibre-/vegetable-poor maternal diet, and/or never breastfeeding. In a 2023 study, researchers demonstrated that mice fed high-fibre diets produced a milk microbiota that increased infant gut propionate levels, leading in turn to increased production of specific cells in the bone marrow that confer protection against respiratory infections. Indeed, therapy with specific propionate-producing bacteria, and even propionate supplementation, were shown to act in a similar way. Fermentable dietary fibre favourably influences the gut microbiome resulting in the production of metabolites that modulate the immune system (particularly short-chain fatty acids — SFAs). It is widely accepted that SFAs play an important part in regulating intestinal barrier integrity, and there is now evidence that they have a role in placental structure and vascularisation. Breastmilk also contains regulatory cytokines, growth factors and oligosaccharides, all of which influence the developing infant. Metabolic disorders, such as gestational diabetes, affect the levels of SCFAs and other metabolically significant metabolites causing changes in the maternal immune system with knock-on effects for the developing foetus. The authors of this study suggested that the “manipulation of the maternal diet during pregnancy and during the pre-weaning period, or through the provision of defined tailor-made prebiotics and/or probiotics directly to infants, may present novel opportunities for enhancing resistance to inflammation-mediated diseases.” Other researchers have described the transport of even more molecules across the placenta, including lipopolysaccharides and other bacterial cell fragments. Preconception infections with some intestinal parasites can lead to maternal imprinting in mouse offspring, thereby suggesting that the transfer of immunity is not solely dependent on the passive transfer of antibodies. 

These metabolites may also exert an effect on the genetic material within cells. Epigenetics is the set of factors and molecules that modify gene expression while not changing the genome sequence itself. Only around 2% of mammalian DNA is associated with protein-encoding genes; the rest (non-coding DNA — what used to be referred to as ‘junk DNA’) modifies the links on the chain to switch genes on and off at crucial junctures. These modifications are commonly associated with environmental cues — good and bad — that can result in significantly different outcomes (phenotypic plasticity) for two genetically identical individuals. In one Danish study, children who exhibited allergic rhinitis at the age of six were found to have a distinct DNA methylation pattern (an epigenetic signature) in their nasal mucosal cells associated with reduced microbial diversity at one week of life. It was folate’s role in countering the development of neural tube defects that first pointed to the foetal nutritional programming hypothesis through epigenetic programming. And as the stage most susceptible to environmental stressors is embryogenesis, where DNA methylation is closely associated with optimal differentiation and growth, consideration of preconception dietary factors is fundamental (folate supplements are recommended when pregnancy planning, but gut bacteria produce significant amounts of folate in humans with a healthy microbiome).

While epigenetic changes do not change the base-pair sequences within the genome, they are heritable, meaning that future generations may inherit far more than just the A–T and G–C building blocks. It seems certain that different epigenetic mechanisms may partly explain why dietary factors at critical developmental stages might affect the susceptibility to diseases in adulthood. 

With microbes contributing 99% of all genetic information present in the body, maternal microbial transmission should be viewed as an additional and important mechanism of genetic and functional change in evolution. Horses are selected for characteristics such as temperament, strength, speed, and endurance. Although genetic selection tools have been developed to assist breeders in the choice of sires and dams, there is also a growing body of research reporting that the maternal environment modulates the genetic potential of the offspring. Under natural conditions, microbes that promote host fitness, especially in females, will simultaneously increase their odds of being transferred to the next generation. Under controlled breeding programmes, efforts to assist this beneficial effect should be encouraged: the trajectory of the young foal’s colonisation process has lifelong clinical implications. And being aware of its influence may not only improve the outlook for your foal, but your foal’s foals as well. 

Guest Author

Why Broodmare Body Condition Matters

It’s common practice to maintain broodmares in what is considered “good condition.” In reality, this often means mares are kept overweight, based on the belief that heavier mares are more fertile.

But research and field experience suggest otherwise. Excess body fat in broodmares is associated with an increased risk of developmental orthopaedic disease (DOD) in their offspring, including:

• Osteochondrosis (OC)
• Osteochondritis dissecans (OCD)
• Angular limb deformities
• Flexural limb deformities

These conditions can significantly impact sale value, veterinary expenses, training timelines, and long-term soundness and performance outcomes.

The Hidden Problem: “Good Doers” & Nutritional Imbalance

When it comes to health and nutrition of broodmares, some of the most common issues I see in practice are:

• Misjudged body condition
• Underestimated nutrient requirements
• Over-reliance on pasture alone as a sole or primary feed source
• Haphazard or uninformed supplement use
• Feeding based solely on body weight and condition, not nutrient requirements

This is especially true for “good doing” mares. In an effort to control weight, many broodmares are not feed sufficient quantities of a suitably fortified feed or mineral balancer, meaning they:

• Lack key minerals needed for fertility, immune function and foetal growth and development (e.g. copper, zinc, calcium, magnesium, selenium, iodine)
• Receive inadequate micronutrient support
• May not consume sufficient amounts of essential amino acids such as lysine
• Still consume excess energy

This results is a mare that is overweight but undernourished. The implications of these don’t just impact her immediate health, but reproductive outcomes.

At the same time, supplemental feed, vitamin or minerals are often added without a clear understanding of:

• What the mare actually requires
• How her nutrient needs change from preconception, during the different stages of pregnancy, through to lactation
• Correct dosages
• How nutrients interact
• How any medications the mare may be receiving impact nutrient requirements 
• What is already being supplied through pasture and current diet

This can lead to:

• Nutrient imbalances
• Shortfalls in key nutrients required for optimal reproductive health and sound orthopaedic development of the mare’s offspring
• Excesses of nutrients that interfere with absorption of other minerals
• A false sense of “covering all bases”

More supplements generally don’t equate to better nutrition: precision matters. And when it comes to the healthy development of young horses, this is an area which you cannot afford to overlook.

Nutrition & Orthopaedic Development Are Linked

When managing DOD risk in young horses, nutrition and body condition cannot be separated.

All of the following may increase DOD risk:

• Overfeeding energy
• Poor gut microbial health (in both the mare and/or foal)
• Underfeeding essential nutrients
• Feeding certain minerals in excess
• Mineral imbalances
• Inconsistent feeding practices
• Sudden changes in feed
• Feeding in ways that promote high insulin levels

A foal’s orthopaedic health doesn’t start at birth: it starts with how the mare is managed before conception and throughout pregnancy.

The Real Cost of Getting It Wrong

Many developmental issues don’t appear immediately. Instead, they show up later as:

• Swelling, stiffness, lameness (sometimes only subtly)
• Radiograph (x-ray) findings
• Inconsistent performance
• Reduced athletic potential

By that point, the financial and reputational costs are significantly higher.

How to Get It Right

Optimising broodmare nutrition isn’t about feeding less or more, it’s about feeding in a way that promotes health and fertility in the broodmare and sound orthopaedic development in her offspring.

That means:

• Maintaining an appropriate body condition score (not overweight)
• Providing balanced minerals and trace elements in forms which the mare can readily digest, absorb and metabolise
• Adjusting feeding based on pasture, environmental conditions, and reproductive stage
• Ensuring energy (calorie) intake is appropriate given the mare’s unique requirements
• Taking a mare’s reproductive history into account and addressing specific nutrient requirements in relation to this
• Monitoring condition consistently and objectively
• Assessing and addressing the nutritional and metabolic impact of any medications a mare may be receiving 
• Feeding to promote optimal gastrointestinal health

Need Help Assessing Your Broodmare Program?

If you’re unsure:

• Where your mare’s body condition currently sits
• Whether her diet is properly balanced
• Specific nutritional requirements of your broodmare
• How to reduce DOD risk in your youngstock
• Why you mare may struggle with fertility or reproductive challenges, despite extensive veterinary intervention

Now is the time to address it, before small issues become expensive problems.

I work with breeders to optimise broodmare nutrition and management, supporting both fertility and the long-term soundness of their youngstock.

If you’d like a clearer understanding of where your mares currently sit and how to improve outcomes heading into the breeding season, feel free to get in touch.

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

The way a foal enters the world can have a lasting impact on its gut health, immune function, and even its risk for developing inflammatory conditions later in life.

In the absence of infection, foals in utero have sterile intestines. 

The ‘healthy’ bacteria needed to colonise the foal’s gut microbiota primarily come from the maternal birth canal and rectum. Through the process of normal delivery, these bacteria are swallowed by the foal, travelling through the stomach and colonising the upper and lower intestine, a complicated process that evolves rapidly.

Foals born via cesarean section fail to encounter the bacteria of the birth canal and maternal rectum. Instead, bacteria from the skin and environment they are delivered in, quickly populate the bowel. As a result, the bacteria inhabiting the lower intestine following a cesarean birth can differ significantly from those found in the vaginally-born foal. Foals born via cesarean are likely to have different, less beneficial and health promoting bacteria to those foals born normally.

Through either mode of delivery, a core gut microbiota is well established within a few weeks of life. This bacterial balance persists largely intact throughout life. A less stable peripheral microbiota—one that is more sensitive to changes in diet and environmental factors, like antibiotics—is also formed.
In cases where cesarean deliveries are necessitated, there are strategies which can be employed to help establish and promote a healthier balance of microflora, thereby positively influencing the foal’s health for life.

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

In the lead up to and during breeding season, many pregnant mares are relocated to different properties from where they are normally kept, in order to be foaled down.

Mares which are to foal at properties different to where they are currently residing should be moved a minimum of 30 days prior to foaling. It is generally well accepted not to travel a mare close to foaling (due to increased cortisol levels in response to travel, which influence hormonal changes and can induce labour). What few people actually stop to consider is the importance of the environment the mare is kept in prior to foaling and the impact it has on her foal’s immune system.

The newborn foal is entirely dependent on the antibodies provided in the colostrum by its dam (unlike humans, foals are not born with any circulating antibodies) in order to prevent/fight infection.

The antibodies contained in a mare’s colostrum are active against microorganisms specific to that mare’s environment: whatever might be circulating on the farm she is kept on, as well as against pathogens the mare has confronted or been vaccinated against in the past.

By ensuring mares are moved in a timely manner to the property where they will foal, they are able to stimulate colostral antibody production to local pathogens, thereby helping to pass these onto the offspring, giving their foal’s immune system the best chance to ward off pathogens specific to the environment it is in.

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

When feeding heavily pregnant mares, many focus primarily on providing increased calories to the mare. Unfortunately, the importance of trace minerals often gets overlooked. 

Zinc, selenium and copper in particular are low in mares milk. For a foal’s requirements of these minerals to be met, the pregnant mare must have received sufficient amounts of these during pregnancy (and as research continues to support, even prior to pregnancy). This allows the unborn foal’s liver to be fortified with these nutrients prior to birth. 

The foal draws upon the supplies of these minerals from the liver for the first couple of months of life. This is essential to support healthy skeletal growth. Insufficient stores of these trace minerals may predispose foals to growth disorders and conditions such as osteochondrosis and osteochondritis dissecans (OCD).

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

Research has demonstrated that during the last three to four months of pregnancy, the developing foetus will gain approximately 70-80% of its birth weight! To support this rapid foetal growth, a pregnant mare’s nutritional requirements greatly increase.

Without a mare receiving proper nutrition during this important phase of pregnancy, her foal’s long-term health and development may be compromised. Such nutritional implications are associated with a predisposition for skeletal growth disorders (such as osteochrondrosis and osteochondritis dissecans [OCDs]) in her offspring.

Appropriately feeding a mare during this phase can become challenging- especially when she is a ‘good-doer’ or has a tendency to get fat: research has demonstrated that another risk factor predisposing young horses to orthopaedic development disorders is being born to mares who carry excess body weight (and particularly body fat) during pregnancy. Keeping such mares at a healthy bodyweight is even more difficult in areas where there is abundant pasture. Unfortunately, however, pasture alone will not meet a mare  and her developing foetus’ nutritional requirements. Nor will the provision of a mineral salt lick/block.

There is a happy balance however, to support a mare and her developing foetus’ nutritional requirements, whilst also ensuring a mare is kept at a healthy body weight and condition. This helps to give a foal its best chance at life and healthy orthopaedic development and is one critical strategy to help prevent orthopaedic developmental disorders as the foal grows and matures. It is also one of the most important factors to assist a mare getting back in foal, should she be covered or inseminated again. 

The long-term health and athletic performance of our horses starts with conception (and even pre-conception). To learn more about how we can help your horses visit our services page.

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

At birth, foals have only achieved approximately 17% of their mature bone mineral content. What we feed our broodmares (and therefore, the nutrients passed from a mare’s milk to her foal) has significant influence on healthy bone and joint growth and development, immune function, and overall health. A newborn foal consumes 15-25% of its body weight in milk daily. It may also nurse from its mother an incredible 70-80 times per day! In the first few days of life it may nurse even more frequently…as often as every 10 minutes.

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

Foals and coprophagy

Foals will generally start consuming manure from about five days old. It is common for this to occur up until approximately three months of age, before gradually declining. By 19 weeks of age, the habit generally stops in most foals.

By consuming manure, foals are populating their digestive system with a variety of microbes: bacteria, protozoa, archea and fungi. This habit is thought to be an important part of healthy gastrointestinal and immune system development: foals are born with a relatively ‘immature’ microbiome which is influenced by multiple factors in their early stages of life. It is worth keeping in mind however, that if a foal is consuming manure from a horse with poor digestive health and/or a horse with a poor balance of microflora and/or a horse with a high parasite burden then this may potentially have adverse effects in the foal.

Inferred research from other animal models suggests that a mare’s faeces contains a pheromone which encourages the foal to consume the manure.  Deoxycholic acid is believed to be present in a mare’s manure: an important byproduct of intestinal bacteria which supports digestive system immunity (helping to protect against enteritis). Deoxycholic acid may also facilitate normal neurological development through promoting myelination of nerves.

Adult horses and coprophagy

The consumption of manure in horses and ponies older than foals is considered an abnormal behaviour. When it does occur, it is thought to be primarily diet and/or gastrointestinal (GI) health related.

A diet low in dry matter fibre (often referred to as ‘roughage’) is one of the most common reasons a horse may consume manure. It is a common misconception that pasture alone provides enough fibre for our horses and ponies, but grass is very low in dry matter fibre. Without feeding appropriate amounts of hay or alternative dry matter fibre sources, the vast majority of horses and ponies will fail to meet their requirements.

Other diet related factors which may contribute to coprophagy include:

• Diets high in starch: even when there is adequate dry matter fibre in the diet;
• Underfeeding and/or food scarcity;
• Long periods of time without access to feed (for example, going more than three hours without access to hay/pasture and/or hard feed);
• Poor gastrointestinal (GI) microflora populations (diet related);
• Specific nutrient insufficiencies and/or deficiencies: potentially vitamin K, selenium and/or zinc.

Dietary factors aside, anything that significantly disrupts a healthy GI microflora balance can contribute to coprophagy. This can include the use of many common medications (such as antibiotics, non-steroidal anti-inflammatory drugs; corticosteroids, gastric ulcer medications); stress in all of its many forms (!); dehydration; travel, etc.

Other less common reasons an adult horse may consume manure can include medical conditions such as equine motor neurone disease.

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

In addition to compromising the health, vitality, growth and immune function of the foal, Rotavirus has been associated with gastrointestinal ulceration in foals.

This is likely due to nutritional and systemic stress, interruption of suckling in foals and the direct damage the virus causes to the epithelial cells which line the gastrointestinal (GI) tract.

In addition to appropriate veterinary treatment (where required), strategic use of appropriate nutritional supplements and herbal medicines can help restore integrity to the digestive system, support immune function, and optimise the health and growth rate of the foal.

It is worth keeping in mind that commonly prescribed ulcer medications (those containing omeprazole or ranitidine) can adversely impact nutrient availability- including key nutrients needed for both immune function and proper restoration of the GI epithelial lining. To learn more about the effects of ulcer medications visit Ulcers in Horses: The importance of understanding how medications work.

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

These include intrauterine positioning, ingestion of certain toxins by the mare, hypothyroidism in the mare, collagen cross-linking defects, and unidentified predisposing genetic factors.

Two interrelated and important controllable factors are diet/nutrition and the body condition of an in foal mare.  Overly fat mares, and/or mares that are fed diets high in relative energy may have a greater risk of having foals with flexural limb deformities. 

Many mares are overfed late in pregnancy in attempts to supply adequate nutrition to the developing foal. This is compounded by the perception that fat mares are often mistakingly associated with looking ‘well’. 

Additionally, certain nutrient insufficiencies and/or deficiencies may lead to the development of congenital flexural limb deformities. 

This can become confusing when mares have a surplus of calories (and look ‘well’) yet do not have sufficient key nutrients to facilitate normal development of the foal in utero. A similar analogy that may be helpful in understanding is to think of a person who lives on takeaways, desserts and overly processed foods. Whilst they are likely consuming enough calories, they will be falling well short of key vitamin, mineral, essential fatty acid and possibly amino acid requirements.

The way we feed and manage our broodmares influences the health of their offspring for life. Ensuring their diet provides key nutrients in appropriate forms and amounts is one of the best things we can do to help facilitate the best health and development in their foal.

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

To use a similar analogy, it can be helpful to think of commercial breakfast cereals. Take for example, Coco Pops or Nutrigrain. Both these kinds of cereal are enriched with certain vitamins and minerals which are essential to good health. Marketing of these cereals promotes this fact. But vitamins and minerals alone don’t necessarily make a particular food a good choice. They are only part of the equation. These cereals aren’t marketed as being high in sugar, or devoid of essential and health-promoting nutrients such as fibre. In reality, these cereals are low in nutritive value, yet clever marketing can have us believe that these are nutritious choices.

Some commercial broodmare feeds can be similar in that they are fortified with essential vitamins and minerals, with not a great composition of the feed overall. Many feeds designed for broodmares can be high in starch and/or energy, which can contribute to undesirable levels of particular hormones in a mare. These in turn affect the growth and health of the developing foetus. We also know that these hormones, in addition to a mare’s body condition influence her offspring’s risk of orthopaedic lesions such osteochondritis dissecans (OCD). It is common for many broodmares to be overfed and/or overweight which compounds the problem.

How we feed a mare and the body condition we maintain her in pre-conception and during pregnancy have a profound effect on the musculoskeletal development and soundness of her offspring. This influence extends well past the period of birth and weaning, affecting the growing young horse. To only focus on OCD lesions during routine or pre-sale radiographic screening as weanlings or yearlings is like trying to close the gate after the horse has bolted.

Whilst surgery can be effective, and diet and risk factors in young growing horses can be modified, missing the opportunity to set foundations right pre-birth can be expensive, time-consuming and heart-breaking.

It’s worth stopping to have a good look at the ingredients in your stud mix/broodmare feed, looking beyond the marketing claims. There’s much more than vitamins and minerals alone required to promote a healthy pregnancy and the development of a mare’s offspring.

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

Research has clearly demonstrated that weaning is a stressful period in a foal’s life. From a biochemical perspective, this results in the stress hormone cortisol being produced at very high levels.

Stress (and in turn high cortisol levels) affect the horse’s immune system in many different ways. It commonly reduces the body’s ability to mount or maintain an effective immune response and immunity. The high levels of cortisol may decrease the production of specialised cells of the immune system and reduce the appropriate response of the immune system to the vaccine. This results in a less effective response to vaccination and less protection from what we’re trying to vaccinate the foal against. In some horses, this can result in ‘vaccination breakthroughs’ where the horse still gets the disease despite being vaccinated for it.

As a general rule, timing vaccinations at least 2-4 weeks away from the time of being weaned may help the horse to have the most effective response to vaccination and reduce the likelihood of vaccination breakthroughs. 

The use of appropriately prescribed specific nutritional supplements and herbal medicines around the time of weaning and vaccination can be invaluable. Key pathways can be targeted to help modulate the stress response and support optimal immune response to vaccination.

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

Selenium is a nutrient which has a relatively low safe upper limit range. High intakes (through diet and/or supplementation) can result in toxicity and even death in severe cases.

Many parts of the world have soils that are notoriously deficient in selenium- and thus the pastures and feeds grown for horses in them are also low in selenium. This has led to selenium being a commonly added mineral to horse feeds and many supplements.

Selenium comes in two main forms: organic and inorganic. Organic selenium has been demonstrated to have superior absorption, tissue uptake and ability to enhance antioxidant status compared to inorganic selenium. This is attributed to selenomethionine, the effective organic part of organic selenium.

One of the most popular sources of selenium used in horse feeds and supplements is selenium yeast (produced by them is the micro-organism Saccharomyces cerevisiae). Although selenium yeast contains high levels of organic selenium, not all of it is in the form of selenomethionine. Research has demonstrated that there are significant limitations in using selenium yeast to help achieve good selenium uptake and stores in the body. Although the product should in theory contain a certain amount of organic selenium on paper, the actual amount of organic selenium in the form of selenomethionine provided by selenium-containing yeast is often far less. A large percentage of the selenium provided by selenium-containing yeast is in a poorly absorbed inorganic form. This means that your horse is potentially utilising much less selenium than what is written on the label and may well be falling short of their requirements. Not all feeds and supplements use this form of selenium- so it is incredibly valuable to ascertain not only the amount of selenium in a product but also the form it is in. Seemingly minor details in feed and supplement formulations can have profound influences on our horse’s health and wellbeing.

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

Many regions in the world have low iodine levels in the soil. Iodine deficient soils are most common in inland regions, mountainous areas, land that frequently floods, and on occasion, some coastal regions. Unless horse diets are adequately supplemented, horses that graze on pastures in these regions and/or consume hay and feed crops grown in these areas, are likely to fall well short of their minimal iodine requirements. Research has also demonstrated reduced uptake of iodine by pastures which have been grown with high levels of nitrogen fertilisers, even in soils with otherwise reasonable iodine levels.

Like many minerals however, too much iodine can be just as problematic as too little iodine. This can easily occur when our horses are given multiple supplements, and/or feeding inappropriate quantities of fortified feeds. An innocent mistake commonly made in relation to iodine supplementation is the use of seaweed supplements. In many cases, this can result in excessive iodine intake.

Many clinical signs and health consequences of iodine excess often mimic those of iodine deficiency. An important reminder that more is not better, and supplementing without taking specific details into account can be detrimental to horse health, fertility, metabolic function, growth and development.

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

If a foal doesn’t receive or absorb adequate levels of colostrum within 16 hours of birth, it is predisposed to a higher risk of bacterial infection. The capacity of the small intestine to absorb and transfer antibodies is greatest during the first 6-8 hours after birth. Thus the sooner a foal gets colostrum into it, the better. A foal’s ability to absorb colostrum declines substantially after 12 hours and within 24 hours after birth the specialised intestinal cells which absorb colostrum are replaced by cells incapable of transferring antibodies.

Colostrum contains three types of protein immunoglobulins:

*IgG- which helps to provide immunity against bacterial and infective diseases;
*IgM- for general immunity
*IgA- which increases in milk after a mare has foaled. IgA is unique in that it is not absorbed into the body. It provides local gut protection against bacteria, viruses and other germs that can cause diarrhoea in a foal.

Colostrum also has a natural laxative effect- which helps stimulate a foal’s bowels to promote the passing of meconium (accumulated wastes).

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

This yellowish, greenish, watery diarrhoea generally occurs in foals around 7-14 days of age, hence often coinciding when a mare comes into foaling heat. We know, however, that orphan foals and foals reared in isolation from mares commonly develop this characteristic type of scours: thereby indicating that mare hormonal fluctuations alone do not drive their development.

This type of diarrhoea is more accurately attributed to the changes occurring in the developing hindgut of the foal. Foals of this age are starting to consume grass (having initially relied entirely on nursing milk from their dams). The proper digestion of grass requires the actions of specific microbes in the hindgut. Foals aren’t born with these microbes- they are established upon exposure to feed and various environmental conditions.

Until the microbial population is well colonised in the hindgut and digestive enzyme secretion normalises in the foal, the fibre from grass remains largely undigested. The result? Yellowish, greenish scours which often contain visible clumps of undigested grass.

Foal heat scours are generally nothing to be concerned about and are easily distinguished from infectious forms of diarrhoea (such as Rotavirus or Salmonella) which are systemic illnesses. Foals experiencing foal heat diarrhoea do not have a fever, and remain bright, alert, active and on suck.

There are other forms of non-infectious diarrhoea in the foal which include lactose intolerance, overfeeding, ingestion of sand, administration of some antibiotics, and in some cases the use of NSAIDs (such as phenylbutazone ‘bute’/‘PBZ’ and flunixin).

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.

OC is a disease that causes lesions in the cartilage and bone of growing horses’ joints. It is a result of cartilage failing to properly turn into bone. OCD occurs as a progression of the OC: resulting in the formation of a cartilage flap or osteochondral fragment.

Like many health conditions, there are numerous potential causes and contributing factors to the development of both OC and OCD. One such factor which has been identified to increase the risk of developing osteochondral lesions is restricted turnout of foals. Research has demonstrated that foals (particularly those younger than two months) who are able to exercise freely in a moderate-sized paddock, have a much lower risk of developing osteochondral lesions when compared to foals that are stabled.

An ounce of prevention is worth a pound of cure. Sound management and feeding practices can save a lot of time, heartache, and expense. Getting back to the basics and not overly ‘protecting’ our horses can go a long way to ensuring we have the happiest, healthiest athletes.

Optim Equine

Camilla Whishaw is a highly regarded, experienced horsewoman and naturopath, helping to holistically treat and manage a broad range of equine health conditions and injuries, with a passion for mare and stallion fertility.

As a world-renowned practitioner, presenter, author, and consultant in the field of Equine Naturopathy, Camilla shares her knowledge through keynote presentations, interviews, lectures, panel sessions, and workshop training.