Common Nutrient Deficiencies in Horses and How to Spot Them

Horses often return from winter with less condition, especially if they've been predominantly living outside. Fortunately, with the right diet comprising good quality hay and appropriate hard feed, they usually regain their condition fairly quickly. However, even with balanced commercial feeds formulated to provide essential minerals, vitamins, and nutrients, some horses can still develop specific nutrient deficiencies that impact their health and performance.

Horses More Susceptible to Nutrient Deficiencies

Certain groups of horses are particularly at risk. Performance and competition horses, those in hard work, pregnant and lactating mares, as well as young horses under two years old, have increased nutrient demands. Additionally, horses confined indoors on hay-only diets without access to pasture face greater risk of deficiencies.

Studies, including from the KER University and veterinary sources, highlight how hay-only diets can lack critical nutrients, especially Vitamin E, which naturally occurs mostly in fresh grass. Lower Vitamin E means a weaker immune system, respiratory issues, and problems with vitamin A absorption.

Vitamin E Deficiency: Signs and Management

Vitamin E deficiency can lead to severe conditions such as equine motor neuron disease and equine degenerative myeloencephalopathy, both of which affect the horse's nervous system. Testing forage for vitamin E content is the most reliable way to assess if supplementation is needed. Supplements should contain the natural form, d-α tocopherol, which horses absorb better than synthetic versions. Always consult your vet before adding supplements to your horse's diet.

Essential Role of Vitamin A

Vitamin A is vital for young horses’ vision, muscle, and bone development, as well as skin health and immune system support. Horses generally obtain sufficient vitamin A from fresh grass, but levels drop noticeably in hay, which is not fortified with this vitamin. Horses on hay-only diets especially require monitoring to avoid deficiency.

Vitamin C and B Vitamins in Stress and Illness

Vitamin C, known for its antioxidant and immune-boosting properties, is produced internally but may be insufficient during prolonged stress such as weaning. B vitamins, produced in the hindgut, support skin, muscle, nervous system, and immune health. Ill or stressed horses often reduce their feed intake, leading to decreased hindgut function and subsequent vitamin B deficiencies. Ensuring a horse returns to normal feeding habits quickly is important to prevent these issues.

Salt and Mineral Balance: Salt, Calcium and Phosphorus

Salt deficiency can cause metabolic issues, especially in working horses, as natural forage and even commercial feeds may not provide enough salt. The calcium to phosphorus balance is equally crucial. Adult horses need a 1:1 ratio, while young growing horses require a 2:1 ratio. Imbalances can contribute to lameness and conditions like osteochondritis dissecans. Misdiagnosed lameness is sometimes due to nutrient imbalances rather than injury.

Recognising Nutrient Deficiency Symptoms

Deficiencies commonly manifest as dull coats, brittle hooves, unexplained lameness, poor growth, fatigue, and susceptibility to infections. Such signs might be subtle and attributed to other causes, underscoring the importance of veterinary consultation and appropriate testing before supplementation.

Conclusion: Prioritising Balanced Nutrition and Vet Guidance

If you suspect your horse is deficient in any nutrients, seek veterinary advice immediately. Your vet or equine nutritionist can conduct tests to identify nutrient gaps and advise on appropriate dietary adjustments or supplements. Any changes to diet should be made gradually to protect your horse's delicate digestive system. Responsible feeding, tailored to your horse's individual needs, plays a key role in ensuring their health, performance, and well-being.