Notice how your body feels sore after an intense workout? That’s because exercise results in microscopic tears in your muscle fibers. Not to worry, these tears are necessary for your muscles to grow and get stronger. The same is true for horses; although there comes a point in both species where this sensation is evidence of something bad. Sometimes the stiffness and sore muscles happen alarmingly fast, either during exercise or immediately after. When this happens, the horse’s muscles cramp up and start to break down.
The scientific term for this phenomenon is equine exertional rhabdomyolysis, but it’s more commonly known by the terms tying up, azoturia, set fast or Monday Morning Disease. It mostly affects a horse’s lower back, gluteus and quads, although there have been cases concerning the front limbs. When a horse is suffering from azoturia, his or her muscles will be firm to the touch, and palpating the area will cause pain.
Most sporadic cases of tying up occur because a horse was pushed beyond its level of physical fitness, while chronic cases occur in animals with a genetic predisposition. The cramping and stiffening starts less than 30 minutes into an exercise routine. When this happens, horses stiffen up and their gait becomes stilted. Other symptoms include sweating, shallow breathing, rapid heart rate, muscle tremors, recumbency and a refusal to move.
When a horse is tied up, its damaged muscles release myoglobin into the blood stream. Myoglobin has a dark pigment that is highly toxic and filtered through the kidneys, causing the urine to turn brown or dark red. The filtration process damages the kidneys and can, in severe cases, lead to acute renal failure. Although tying up itself isn’t fatal, renal disease can be.
Diagnosis and treatment
A blood test that looks for elevated enzymes will tell you if your horse has recently suffered from exertional rhabdomyolysis. Damaged muscles release creatine kinase and aspartate transaminase. According to Horse Canada, equines that have recently tied up have CK and AST levels that are hundreds to a thousand times the normal, healthy range.
Regardless, if you notice your horse starting to cramp or spasm, stop exercising immediately. Even forcing your companion to walk can damage its muscles and worsen the problem. If you must move, keep your horse somewhere it cannot move, like a stable or trailer, and drape its hindquarters with a blanket. Your veterinarian might prescribe muscle relaxers or anti-inflammatory medications, which should be given as instructed. If your horse’s urine is dark, give it water to help flush the myoglobin pigment out of its system. Adding daily equine electrolytes like Apple-A-Day or Orange-A-Day will help your horse maintain the right balance as its water intake increases.
Using horse vitamins and supplements to prevent tying up
Evidence suggests the right balance of vitamin E and selenium supports proper muscle function, possibly preventing mild or recurring cases of tying up. Both are antioxidants and protect a horse’s cells from suffering damage from the free radicals produced by normal oxidation. Many areas in the U.S. are deficient in selenium, so equine supplements might be necessary to give your horse the proper mix of both nutrients. B vitamins also play a critical role in maintaining healthy muscle function as they provide cellular energy and help the body process lactic acid in muscles. finish Line’s JC’s X-Tie Up and Lactavite both support healthy muscle function.