Vitamin Deficiencies in Horses

Vitamins A, C, E, D, Thiamine, Riboflavin and B12 are some of the vitamins needed by cells to function in various systems of your horse. While the symptoms of the deficiencies may differ slightly between each vitamin, as will the equine system which is affected, here is a range of what you could see if a vitamin deficiency exists in your horse:

• Vision/eye changes - specifically reduced ability to see in dim or low light conditions, increased tearing, changes in clarity of the cornea

• Immune system - increased sensitivity to pneumonia
• Impaired reproduction
• Increased appetite

• Muscles - progressive weakness

• Hoof changes
• Damage to skeletal muscles
• Stiff and swollen joints

As you can see, the various vitamin deficiencies can affect immune, skeletal, ocular, neurological and digestive systems of your horse. 

Types 

There are no specific types of vitamin deficiencies in horses except as they apply to each of the vitamins needed by the horse to function, reproduce and survive. There are, of course, degrees of deficiency of each of the vitamins and those degrees will be identified by the signs, symptoms and the diagnostic testing done by your veterinary professional.

The causes of the various vitamin deficiencies in your horse will likely stem from the diet you are feeding your equine. Here are some things which can have an effect on vitamin intake and processing in your horse’s system:

• Feeding dry, low-quality hay for extended periods of time
• Vitamin E, for example, is lost quickly in stored hay, grains and feeds
• Long periods of confinement without sunlight causes decreased vitamin D, this is especially true in the case of young foals
• Reduction in the feeding of sun-cured hay which boosts vitamin D
• Stress on your equine can affect how his body processes the feed and the vitamins contained in it

When a nutritional type of problem exists with your horse, treatment will depend on the cause and diagnosis of the problem, which can be a challenging task for your veterinary professional. He will need a history from you, the owner, which might be a pretty simple explanation that the horse got into the grain bin or that he wandered into a pasture to graze on less than desirable forage. But, it can be more complex, requiring a more complete history from you which will likely include things like:

• Whether the horse has been feeding on hay, grain or pasture 
• The length of time the horse has been fed this food 
• The feeding schedule being utilized
• The type and amount of feed being given 
• How many other horses (if applicable) are affected 
• Any deworming schedule that is being utilized
• Your assessment of the horse’s behavior 

Your vet will do a thorough physical examination and go over your complete history, likely asking questions to clarify or add to your history. He will also likely need to evaluate samples of the feed being given, checking for mold and toxic weeds or other contaminants. He will likely require a variety of tissue samples from the horse. Also, expect that blood work will likely need to be taken to ascertain certain levels of nutritional and blood components that are generally affected when a vitamin deficiency is present. He will also check for parasitic involvement in the tissue samples and the physical examination he does.

Once your veterinary professional has obtained a diagnosis for the condition from which your horse is suffering, he will develop an appropriate treatment plan. This plan could include adjusting the feeding schedule currently being employed, or it could require adjustments of the amounts of various feeds being offered. It also could require changing the feeding regimen entirely, switching from the current food source to another type, or changing grains being fed. It could ultimately require supplementation of certain vitamins to assure the horse is getting sufficient quantities of those being determined to be deficient.

It is important to note that deficiency of one particular vitamin could potentially cause another to become deficient or upset the balance between other vitamins. This imbalance of vitamins, whether too little or too much, can be at the root of other diseases and conditions of which your horse might be suffering. It is this interaction which makes diagnosis of vitamin deficiencies in horses a complex task.