Micronutrient deficiencies in horses and how to avoid them

All mammals, including horses, need certain vitamins and minerals for essential body functions. These micronutrients can often only be obtained from the diet, so deficiencies can occur if nutritional requirements are not met. Understanding which horses are at risk of deficiencies is the first important step to developing the best supplementation plan for each individual horse.

– Copper deficiency in horses

– Iron deficiency in horses

– Vitamin E deficiency in horses

– Selenium deficiency in horses

– B vitamin deficiency in horses

Copper deficiency in horses

What does copper deficiency in horses look like?

Copper has many roles across the body, including energy utilisation, bone growth, collagen production and coat health/colour. As a result, deficiency can adversely impact athletic performance and is associated with developmental orthopaedic diseases in young horses. However, the effects of copper deficiency are probably most well known as changes to the hair coat and hooves however. The coats of copper deficient horses often appear dull and/or bleached in colour, with brittle manes and tails. Chronic hoof problems, such as brittleness, poor horn growth and even cracks may also be an issue in these animals.

What are the risk factors for copper deficiency in horses?

What are the risk factors for copper deficiency in horses?
– Grazing from land with copper deficient soil

– Forage only diets

– Poor quality hard feed

– Underestimating demand – e.g. pregnant mares, growing youngstock and competition horses have a greater requirement for copper

– A complete feed being fed below the recommended feeding guidelines – e.g. horses on restricted calorie diets

– Interaction with other elements – e.g. iron, zinc and sulphur can impede absorption of copper in the gut, meaning that deficiency can occur, even when adequate amounts are being fed

How can I avoid copper deficiency in my horse?

In known copper-deficient areas, and in horses that have increased demand for copper, daily supplementation is recommended to avoid deficiency. Chelating copper makes it more bioavailable to horses, meaning that absorption is optimised. Coppervit is a daily liquid supplement containing chelated copper and is also fortified with Vitamin E and Vitamin B12 to support growth and development. To correct copper deficiency, or for shorter term copper supplementation support, choose Copper-Max, for the highest dose of chelated copper available to horses, in an easy-to-administer oral paste.

Read more about copper in horses

Iron deficiency in horses

What does iron deficiency in horses look like?

Iron plays a vital role in oxygen transportation around the body, forming a key part of the central haemoglobin molecule in red blood cells. It also plays an important role in ensuring good quality milk in lactating mares, with benefits transferred to the nursing foal. Signs of iron deficiency can be vague, such as fatigue, or reduced performance.

What are the risk factors for iron deficiency in horses?

Horses are good at storing iron in the liver and spleen, to draw upon when needed. When red blood cells reach the end of their natural life and are broken down, the body recycles the iron that is released. This means that iron deficiency is relatively rare in horses, but when it does occur, it is typically associated with increased demand or losses, rather than inadequate intake. This can include:

– pregnancy and lactation

– foals nursing from iron deficient mares

– excessive sweating – e.g. performance horses in hard exercise

– chronic bleeding – e.g. large intestinal parasite burdens, or gastric ulceration

How can I avoid iron deficiency in my horse?

For horses that are at risk of iron deficiency, short term supplement support can be beneficial. Feratone is a liquid supplement containing iron sulphate, which is more bioavailable to the horse than other iron preparations, optimising absorption from the gut. Added B Vitamins further support healthy red blood cell formation.

Vitamin E deficiency in horses

What does Vitamin E deficiency in horses look like?

Vitamin E plays a vital role in horses as an antioxidant – neutralising naturally occurring unstable particles called free radicals. Its action is particularly focused on muscle and nerve cells, so deficiencies often manifest as signs associated with these body systems. This can include gait abnormalities, muscle weakness or trembling, low head carriage and lying down a lot. Severe and/or prolonged deficiency has been associated with neurologic conditions, including equine motor neuron disease. Vitamin E deficiency has also been implicated in fertility problems in horses

What are the risk factors for Vitamin E deficiency in horses?

Horses cannot synthesise Vitamin E themselves, so it must be obtained through their diet. Vitamin E is found naturally in new, fresh grass, so horses that are turned out on poor pasture, or that have dried hay as their main source of forage may be at risk of Vitamin E deficiency. Horses with a higher demand for Vitamin E, such as performance animals that are naturally producing higher levels of free radicals during exertion, young, growing horses and breeding animals are also more susceptible to deficiency. Illness can also increase requirements for Vitamin E to support the immune system, rapidly depleting stores in the body.

How can I avoid Vitamin E deficiency in my horse?

Although vitamin E can be stored in the liver of horses, toxicity is extremely unlikely in horses, whereas deficiency can be devastating, so supplementation in horses that may be at risk is recommended. Foran Equine’s Vitamin E Supplement is available in a powdered formulation and contains the most biologically available and well researched isoform of vitamin E – alpha tocoherol. Vitamin E works particularly well in conjunction with selenium (see below), so V.S.L., which contains Vitamin E, selenium and the essential amino acid lysine, is a great choice for daily supplementation.

Read more about antioxidants in horses

Selenium deficiency in horses

What does selenium deficiency in horses look like?

Selenium provides powerful antioxidant action in the body, with particular focus on the muscles, making it an essential mineral for horses who rely so heavily on their musculoskeletal system. Selenium deficiency is therefore typically seen as muscle weakness and wasting. This may be perceived as weight loss and weakness can affect muscles such as those controlling swallowing, causing less obvious ‘muscle associated’ signs, such as coughing while eating.

Combined selenium and Vitamin E deficiency can cause a clinical syndrome called white muscle disease. This degenerative disease affects skeletal and cardiac muscle in young, fast growing animals nursing from mares fed a diet low in selenium and vitamin E. Affected foals are often recumbent, with a fast heart rate, fail to suckle, have difficulty swallowing, and have discoloured (red to brown tinged) urine.

Selenium is also important for the immune system and fertility, so poor function of these body systems may also be seen with deficiency.

What are the risk factors for selenium deficiency in horses?

Many soils in the UK and Ireland are selenium deficient, so horses on a high forage diet in these regions are at direct risk of deficiency. The athletic demands of performance horses also increase their requirement for selenium. Because of the risk to nursing foals and selenium’s vital role in fertility, the nutritional supply of selenium should also be considered for all breeding stock.

How can I avoid selenium deficiency in my horse?

Supplementation with selenium is likely to be beneficial for many horses, and particularly breeding stock and performance animals. V.S.L. combines the antioxidant power of selenium and Vitamin E with the essential amino acid lysine, for optimal muscle health and development. Available in both powdered and liquid formulations, V.S.L. is suitable for long-term daily use.

Vitamin B deficiency in horses

What does B Vitamin deficiency in horses look like?

B Vitamins are a group of vitamins that each have unique functions within the body. As a group, they are important in the release of energy from food and many have additional roles related to nerve transmission, immunity and red blood cell production.

Because of their wide-ranging roles in the body, signs of B Vitamin deficiencies can be equally variable and often non-specific. Lethargy or being quicker to fatigue, underperformance, poor appetite and nervous behaviour are all common problems associated with B Vitamin deficiency.

What are the risk factors for B Vitamin deficiency in horses?

Eight of the B Vitamins are essential – meaning that they cannot be synthesised by the horse itself, so much be obtained via the diet. As they are water soluble, B Vitamins are also not stored in the body. This means that deficiencies can occur relatively quickly.

Some of the B Vitamins are synthesised by the microorganisms in the hindgut, so anything that compromises them can have a knock-on effect on B Vitamin levels. This includes dietary changes, disease (including diarrhoea), parasitic burden or antibiotic use. Poor appetite can be both a cause and a symptom of low B Vitamin levels and elderly horses with reduced digestive ability can also be a concern, due to a diminished absorptive capacity for B Vitamins.

Stress, or high exertion can increase B Vitamin consumption. While healthy adult horses can usually produce adequate levels of B Vitamins, there is a difference between the minimum requirements to prevent deficiency symptoms and optimum requirements for maximum performance.

How can I avoid B Vitamin deficiency in my horse?

Daily supplementation of B vitamins via the diet can be very effective to facilitate optimal performance in athletes, as well as support horses with compromised digestive ability or poor appetite. Readily absorbed and utilised when needed, there is no risk of over-supplementation and benefits are seen across multiple body systems.

Suitable for all horses, B-Complete contains all the B Vitamins that are vital for optimal metabolism and blood cell formation. The inclusion of a prebiotic supports the growth of beneficial bacteria in the hindgut, optimising feed utilisation and aiding digestion. This complete B Vitamin equine supplement is also great for promoting appetite during times of increased stress or fatigue.

Read more about B Vitamins and horses

For more information about nutritional deficiencies in horses, and how to avoid them, get in touch with the Foran Equine Team.



1:Neuromuscular diseases related to Vitamin E, Michegan State University, College of Veterinary Medicine – ,What%20equine%20diseases%20are%20directly%20affected%20by%20a%20deficiency%20of,equine %20degenerative%20myeloencephalopathy%20(EDM). Accessed 17th October 2022

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