Help Your Horse Lose Weight – Before it’s too Late!

Emily Steele, DVM

Obesity is a serious problem in today’s horse.  Although our horses don’t look at themselves in the mirror, this extra weight puts your horse at risk for potentially serious diseases.

One common disease related to obesity is Equine Metabolic Syndrome (EMS).  A similar disease in humans is diabetes type 2.  When horses eat a meal, their body turns hay and grain into glucose, the body’s energy source.  In addition, the pancreas releases insulin, which enables the body’s cells to take in glucose and produce energy.  When too much glucose is present, it can be stored in the body as fat.  Once thought to be for storage only, we now know that fat is a very active tissue.  Fat cells are able to release chemicals and hormones that can do serious damage to the body.  In EMS, these factors play a part in causing regular cells in the body to become less sensitive to insulin.  Therefore, when insulin is released, the cells do not take as much glucose in as usual.  The body then senses excess glucose in the bloodstream and makes – more fat!   

Veterinarians are not sure if horses can be pre-disposed to EMS or develop the disease after they become overweight, but they all agree that fat cells make the disease worse.  Keeping a horse at an appropriate weight and feeding a diet low in starches is important in controlling this disease.  

Unfortunately, EMS causes more than weight gain.  Laminitis can be induced in the horse by creating large amounts of sugar in the bloodstream.  Because horses with EMS have difficulty absorbing glucose from the bloodstream, their bodies are practically always in a state of excess sugar.  Therefore, even a “normal” meal can induce laminitis in an EMS horse.  

Obesity can also hinder recovery from laminitis.  If EMS has already developed in a laminitic horse, every meal it eats can produce excess glucose, leading to continued laminitic inflammation.  Another problem in the obese horse with laminitis is its extreme weight.  The goal in laminitis treatment is to reduce inflammation in the foot.  Horses with extra weight have more pressure on their hooves and hence, more difficulty in reducing inflammation.

Many overweight horses are treated for a disease known as hypothyroidism.  Thyroid hormone is produced by the body and is responsible for cell growth and metabolism.  In hypothyroidism, too little thyroid hormone is made and the cells “slow down”, which can lead to excess weight gain, lethargy, reproductive problems and laminitis.  For many years, researchers believed that the problem came from an abnormal thyroid gland.  Now however, studies suggest that fat cells are able to suppress the thyroid gland.  Therefore, overweight horses may also develop hypothyroidism because of their obesity.  Luckily, a thyroid test and treatment is available to help horses maintain their normal thyroid levels and lose weight. 

Weight loss can be a difficult task for both you and your horse – but it’s worth it.  Here is a plan to help your horse lose weight safely.

1.  Have your veterinarian evaluate your horse’s weight 

2.  Obtain a weight tape – these are inexpensive and are a great help in monitoring your horse’s weight loss 

3.  Stop feeding grain.  Overweight horses do not need grain.   

4.  When losing weight, it is very important that your horse remain on a diet with balanced vitamins and minerals.  Affordable, commercial vitamin/mineral supplements are available in powder or pellet forms. 

5.  Decrease or discontinue grazing time.  It is very helpful to build a stall or dry paddock where there is little or no access to grass.  Alternatively, grazing muzzles are available to control grazing.  Weight loss is possible with a horse on pasture, but consistent weight loss will be more difficult, as it will be tough for you to control portion size.  If grazing is your only feed option, it is best to consult with your veterinarian to determine how much grazing time you should allow your horse.   

6.  It will be much easier to control the quality and quantity of calories your horse receives if you are able to feed hay only.  An exception to this is round bales.  Studies show that a horse can consume all of its daily caloric need in just 2 hours of round bale eating.  If hay is unavailable, many feed companies offer hay replacement products.   

7.  Feeding grass hay is ideal, but first you need to do a little research on your hay.         

• The sugar content of hay can vary greatly between crops, fields, and times of the year.  For under $30, you can have your hay analyzed (contact your veterinarian for details).  Nutritionists use NSC or non-structural carbohydrates to measure sugar content in hay.  Feeding hay with a NSC of less than 10-20% is best for overweight horses.  If you discover that your hay has a higher NSC content, you can decrease sugar in your hay by soaking it for at least 30 minutes before feeding.
   
• It is also important to be able to measure the amount of hay you are feeding your horse.  Many small scales are available that can measure the weight of a hay bale.  On average, a bale of hay weighs 40 lbs.
   
• Once you know the approximate weight of your hay flakes, you can feed your horse according to body weight.  Just like other species, drastic diets are not healthy for horses.  We recommend the following protocol to decrease feed:

·         Week 1-2:  Feed 2% of the horse’s current body weight                

·         Week 3-4:  Feed 1.5% of the horse’s current body weight

·         Week 5 – goal weight achieved:  Feed 1.5% of the horse’s ideal body weight.  If weight loss is not achieved, you may need to further decrease the amount of hay your horse is receiving 

Once your horse reaches its goal weight, it may require slightly more or less hay to keep its weight at a healthy level.  You should continue to monitor your horse’s weight monthly with your weight tape. 

Just as in other species, a great aid to weight loss is exercise.  Riding or lunging your horse for 20-30 minutes every day or every other day is a great way to aid weight loss. 

Helping your horse lose weight will require some extra work.  However, the amount of work and expense will be far greater if your horse develops disease secondary to its obesity.