Problems With Excessive Protein



Protein is absolutely necessary for the body to exist and survive. Without proteins, DNA, enzymes, and hormones would not exist as these substances are primarily composed of proteins. Life cannot be sustained without protein but balance is the key.

An overload of protein will break down the tissues, organs, and the structure of the body over time. Additionally, a horse that consumes too much protein will be at an even greater risk of contracting diseases and be predisposed to other symptoms such as hypothyroidism, tying up, kidney problems, and arthritis to name a few.

Some horses, but generally only a few, do suffer from too little protein in the diet, but most often, if a horse is a having a severe health or behavioural issue, they are presently consuming too much protein in the form of lush grass, alfalfa(lucerne) and/or a high protein hard feed.

We must feed enough protein to maintain condition and integrity of the entire system. However, we must be careful to feed a diet that is no higher, as a general rule, than 12% total protein. Our horses on a high protein diet, may look shiny and healthy for a period of time, but at a cellular level, all is not well.

What goes wrong and why.

  • A high protein diet is acidifying.

Protein levels in diet exceeding 12% cause the body to become "over acidic”.   Feeds when digested are either acid forming or alkalizing to the system. Alfalfa, soy, grains and other high protein feeds are acid forming, whereas most grass hays are alkalizing, apple cider vinegar is an acid yet once digested leaves an alkaline residue and fats and minerals are alkalizing.

  • A horse is hard work such as racing or eventing only requires just over 1 kilogram of protein per day from all sources.
  • Low GI feeds have the carbs taken out but protein added in. Shop carefully!

When the diet exceeds 12% total protein, the top priority of the body is to keep itself alkaline (apart from the stomach acid). When the body has to deal with excessive protein it goes into "emergency buffering or alkalizing” mode and it has several buffering mechanisms available to offset the negative effects of over-acidity. The heart cannot beat correctly in highly over-acid body and the organs must be bathed in an alkaline fluid.

Minerals are alkalizing, so if minerals are not readily available in the blood stream for the heart and organs which the body gives top priority, it will pull the minerals from the bones, ligaments, and tendons to buffer the acid, depriving the structure of vital minerals. Demineralized bones over time become like styro-foam. As the ligaments are demineralized, you may hear clicking in the joints, the horse may develop a sore back as the muscles are having to do more work that the ligaments should be doing. The body will try to stabilize the joints by building up calcium deposits, and you will see splints, spavins, navicular and the like. Permanent unsoundness due to structural demineralization is only a matter of time but may not appear until the horse is seven to nine years old.

  • The horse may appear in great condition

The body will retain water to dilute the acid and the horse can be mistaken for being in "good condition". Once the high protein feed is taken away, the horses will literally urinate themselves thin in a few days to a couple of weeks! They are not losing lean muscle tissue, they are losing the retained water.

  • The toxic urea effect – "My horse has gone mad!”

Some of the excess protein is turned into non-protein nitrogen (urea) and/or nitrates, which are toxic to horses. This toxicity is a common cause of out of character aggressive behaviour, spooking, excessive sweating and the like. The body produces ammonia in an effort to flush excess protein, urea, and nitrates. This process is very hard on the kidneys, not to mention the potential for respiratory problems from inhalation of the ammonia fumes. Healthy urine should be clear, not cloudy and foul smelling.

Alfalfa, AKA Lucerne or so-called Fibre Feeds , are some of the most problematic high protein feeds I come across. Not only is lucerne high in protein, it is high in potassium which can cause severe health and behavioural issues and it also contains large amounts of calcium without balancing magnesium, phosphorus or sodium. 

One NZ company selling a wrapped product recommends feeding adlib, which is extremely unwise given what we know about the out of balance mineral content of alfalfa/lucerne. Dr Karen Hayes, D.V.M., who wrote Modern Horse Breeding, states, "Under no circumstance should the amount of alfalfa in your horse's diet ever exceed 40% (by weight). Any more than that and you are risking the perils of excess protein and excess calcium, both of which can do some unbelievable damage. If your horse's ration consists of 100% alfalfa, he may look healthy, but that does not mean it isn't taxing his system."

  • A tie with Tying Up

According to research performed at Colorado State University and in Sweden, excess dietary protein decreases T4 levels. Optimum T4 levels are necessary for horses to metabolize glucose (blood sugar) properly. When a horse is under strenuous exercise, higher glucose levels are required to fuel the muscles. Higher glucose levels also delay the onset of lactic acid build up in the muscles and blood. Too much lactic acid causes the muscles to lose their ability to contract and relax properly. In this state, the muscles stay contracted/tied up.

We would all agree with the statement that minerals need to be balanced. Too much calcium depletes magnesium so feeding large amounts of calcium laden forage does not make much sense. Magnesium is absolutely essential to relax the muscles after the contraction phase. In the CSU and Sweden studies, higher magnesium levels were found to increase the production of T4 thyroid hormone. Because increased oestrogen depletes magnesium, mares and fillies tend to tie up more frequently on high alfalfa diets as oestrogen is increased during their heat cycles.

Killing off the good guys- An increased chance of disease

In a high protein acidic environment, the horse is more likely to have decreased resistance to parasites and diseases. Too much acid in the intestines will cause the good gut bacteria to go into dormancy and even die, while bad bacteria will actually thrive. Good bacteria in the gut are actually the body's first line of defence against disease. Parasite, bacterial, and viral infections all proliferate in an acidic body, plus with the population of the beneficial gut bacteria being decreased, this gives the infection(s) more ability to survive and overpower the body's immune system.

  • Symptoms like poor attitude, structural and muscular dysfunctions, poor coat condition, kidney stress, etc. can all be due to major protein imbalances.

In Summary

  • Balance is the key to feeding your horse for true health from the inside out

For a large majority of horses, a lower protein diet consisting of top quality grass hay, low protein feeds and proper mineral supplementation will set your horse up for success and promote total health of the whole body and increased performance! A horse that feels good will be easier to work with, will perform better, and experience a longer life.