Understanding Your Horse: Monday Morning Disease

Monday Morning Disease - It sounds like a condition that we all get, once the weekend has come to a close and we're faced with the upcoming work week. Surprisingly though, this is a very frightening condition that can potentially affect our equine companions. Left untreated, it can cause serious problems in affected horses, which may result in permanent lameness.

What Is Monday Morning Disease?

Monday Morning Disease, otherwise known as Equine Exertional Rhabdomyolysis or Azoturia, is a condition which occurs when there is an inadequate supply of blood moving to the muscles of an exercising horse. Because the muscles are working without adequate oxygen, they begin to produce a buildup of acid, waste and heat which damages the cells and causes inflammation of the muscle tissues. This causes the horse extreme pain upon movement, often referred to as "tying up."

Monday Morning Disease can also occur if the horse is fed a diet that is high in carbohydrates. Too many carbohydrates can cause an excess buildup of glycogen (an animal-produced starch) in the muscles when the horse exercises. When he cannot burn off this excess glycogen through normal work, the horse's body continues to try and burn it away even when he is at rest. This also causes a build up of acid, waste and heat in the affected muscles which can result in the horse tying up.

The reason for this condition's unusual name was due to the tendency of farmers and workers to take Sundays off, as a day of rest. While the horses worked hard throughout the week, they would be given Sundays off as well, and were usually rewarded with a full ration of grain. When Monday morning came around and the horses were put to work, the problems would arise, causing the tying up and refusal to move.

The Symptoms of Monday Morning Disease

Horses that are affected with Monday Morning Disease will commonly show signs of tying up - having stiffened muscles and a general reluctance to move. This is due to muscle cramps or spasms, and may be accompanied by sweating for no apparent reason, an accelerated heart rate and rapid breathing. Often, horses that are suffering from MMD may shift their weight from side to side or stand with their backs hunched, attempting to take the weight off the affected area. Passing red-brown or coffee-colored urine is not uncommon and some horses may exhibit signs of shock, due to pain. In severe cases, affected horses may even lose control of their hindquarters, going down and being unable to rise. Heat can often be felt in the affected areas and the muscles are often quite rigid and very hard (often described as wooden).

What Horse Breeds Are At Risk?

The most commonly affected breeds are draft breeds and Warmbloods, but it is also seen in some of the racing breeds such as the Thoroughbred, Arabian or Quarter Horses and related breeds. Some evidence has suggested that there may be a genetic link for horses being more susceptible to this, though there is not yet enough information to substantiate this. It's important to note that all breeds of horse can be affected by this condition, regardless of size or breed.

Diagnosing Monday Morning Disease

If you suspect that your horse may be tying up, due to Azoturia, the best way to diagnose this condition is to have your veterinarian come out and perform a blood test. The vet may also do a urine test as well, just to check the electrolytes in your horse's system. In severe cases of Monday Morning Disease, muscle biopsies may be done, but this is usually only performed on draft breeds or horses that seem to have recurring bouts of tying up.

It's important to note that, if your horse is tying up, do NOT try to force him to move. Doing so can further damage the muscles and harm your horse further. In the event that he ties up some distance from his home, it's imperative that you get a trailer and haul him home, rather than forcing him to travel the distance when he is lame. Taking these precautions and protecting your injured horse can save him from further pain and further injury.

Treating Monday Morning Disease

Horses that are diagnosed with this condition are often given several days worth of anti-inflammatory medications (NSAIDs) and should be rested. If the horse is able to walk without distress, short bouts of walking can help loosen muscles but equine massage and heat therapy may often be beneficial, particularly in horses that are too lame to be exercised. Turning your horse out in a paddock or pasture is also helpful, as it encourages the horse to move gradually and within their physical limits.

If your horse is suffering from Monday Morning Disease, talk to your veterinarian about whether or not you should withhold grain or pellets. Grazing is fine and your horse should be encouraged to drink or he may be given fluid injections, particularly if her urine is very dark. Administering fluids will help your horse flush out the excess myoglobin that may have built up in her system.

Again, horses that are affected with Monday Morning Disease should not be forced to move. It may take several days before she is eager to move very far. In the meantime, hand-walk as tolerated and try letting her rest in a pasture where she can quietly graze and move around on her own accord.

When Can Horses Return To Work?

After suffering from a bout of MMD, it's important to ensure that the horse's symptoms have entirely disappeared and that he is no longer on anti-inflammatory medications. Just to be safe, it's highly recommended that you have your veterinarian perform another blood test, just so you avoid any potential relapses. When your horse is ready to start back, do so slowly, with just small daily practice sessions. Taking him out and letting him walk then jog on the line will help him to adjust. Keep sessions short - only 10-15 minutes to start and then gradually work slowly upward, making sure your horse is capable of more exercise.

When in doubt, have your veterinarian perform a complete physical and suggest a work out regimen for your horse to return to. Taking it slow will help him in the long run.

Sources:

Personal experience, breeding and showing horses
http://www.equineinnovation.com/monday-morning-disease - Information on condition and breeds affected
http://www.horses-and-horse-information.com/articles/0901monday.shtml - More information on MMD