Muscle Problems

Tying Up

Tying Up has been plaguing horse owners for centuries. Known also as azoturia, Monday Morning Sickness, extertional rhabdomyolysis (ER) and myoglobin, this syndrome occurs when a horse suddenly becomes stiff, sweaty and reluctant to move. He may have pain which originates in the back, pelvis and hind limbs. ER is not one disease; rather it is several different diseases with similar signs and different causes.

There are many causes and it is quite misunderstood as to the exact reason horses contract ER. It used to be believed lactic acid caused it but further research is necessary before a specific cause is pinpointed. What is known is that there is a defect in calcium regulation and how it is pumped back and forth into the intercellular storage.

ER can be either sporadic or chronic in nature, and often can be seen in horses which have a diet lacking selenium and Vitamin E.

Cases seen sporadically are usually due to exercise overload, electrolyte depletion or nutritional imbalances. Sporadic episodes respond well to rest, a balanced diet and a gradual return to training.

For others, ER is a chronic issue.

All breeds can be afflicted, but Thoroughbred and Quarter Horses tend to have a higher percentage of cases. There is a common belief ER in Thoroughbreds initiates in the way calcium is regulated by membrane systems in skeletal muscles.

Mares and fillies are most commonly affected, mainly due to their nervous and high strung nature. Your vet may recommend a progesterone regimen to control her heat cycles and offset some of the nervousness.  

This disease may be dormant until the regulatory system malfunction is triggered by any number of causes – stress, excitement, lameness, diets high in grain, and an excess amount of speed while exercising.

An episode of ER may find the horse with pain originating in the back, pelvis and hind limbs. The horse may be in so much pain he refuses to walk. He may exhibit signs similar to that of colic like sweating, and increased heart and respiration rates. Dark red urine is also indicative of tying up, as protein is released from damaged muscle cells and excreted in the urine.

Diagnosis is determined through clinical presentation and also through routine bloodwork. An elevated level of creatine kinase (levels five times above normal) is a good indicator of a horse with ER.  

It is vital to determine the horse whether or not the horse tied up. It may be mistaken for a fracture, laminitis, neurological conditions, poisoning or plant toxicity.

Mild cases can often be difficult to diagnose because the horse may only seem stiff or off. Serious cases need to be diagnosed immediately because massive amounts of muscle damage can cause kidney failure and even death, though rare.

Treatment consists of Acepromazine, Bute, IV DMSO and other fluids.

Dantrium is often prescribed for horses which chronically tie-up. It should be administered prior to exercise.

If you suspect your horse is tying up, immediately stop exercise and move him to a stall. Don’t force him to walk. Call the vet. If it is cool, blanket him. Offer small sips of water if the horse is dehydrated due to sweating. Administer Acepromazine as directed by your vet to relieve any anxiety or pain. Remove feed and give hay until signs subside.

It is a good idea to keep the horse confined in the stall for a few days after the episode. Handwalk daily and turnout once the stiffness is alleviated.

Your vet should work to determine the cause of the ER as an aid to the future. This will be a process done over time, with careful monitoring of exercise, diet and tests such as muscle biopsy.

To keep episodes of tying up at bay, try to minimize stress and excitement in the horse. Adjust his diet to minimize carbohydrates (less than five pounds per day of sweet feed), and add fat.

Commercial feeds such as ADM Senior Glo or ADM Grostrong Ultra Fiber can benefit horses which need a low carb, high fat diet. Balance this type of diet with good quality hay and a vitamin/mineral supplement. All of these work to decrease muscle damage with exercise.

In nervous horses, it will be especially important to establish a routine and gradually increase exercise. These horses may benefit from daily phenytoin (Dilantin  – an anti-epiliptic) or Dantrium. Not all horses which tie up are candidates for prophylactic treatment, however. Your vet will determine if this type of therapy will be beneficial to yours.

You vet can also help create a preventive management plan for horses who chronically tie up. Regular exercise and gradual increases in training, minimizing stress, establishing a daily habitual routine, special diet, and medication can all aid in management of this disease.

             

Seasonal ER

Tying up also is a seasonal affliction. Referred to as pasture myopathy, this non-exercise induced form of ER is believed to be caused by a toxin found in white snakeroot. It is often seen in the fall after inclement weather, as the change in the weather causes plants to store both nutrients and toxins in higher concentrations as a defense mechanism against the elements. The toxin causes an undesirable taste but in a scarce food situation, some horses may consume it.

Seasonal tying-up episodes can progress rapidly, and without aggressive diagnosis and treatment, can be deadly. It is important to supplement with hay once the availability of grass becomes limited to aid in prevention of this disease.