Dr. Lydia Gray of SmartPak Answers Your Questions: Tying Up in Horses (exertional rhabomyolysis)

Originally published in the May 2015 issue of Show Horse Today

Dear Dr. Gray,

I have a question regarding the issue of tying up. I’ve decided to put together a SmartPak for my horse, Liam, to aid in his muscle development. He’s very young (5) and we imported him from Ireland about a year ago, and his current career is 3-day eventing. He’s been developing very well, but last season, I noticed him to be very tired during warm up. He just seemed out of it and not himself at all. After a while he pepped up, but when we completed our course he started tying up. We gave him time off until he got better and now he’s in an excellent and balanced work program. He’s in much better shape then he was last season, however, I’m still concerned with his fatigue. He gets so worn out, especially with the heat we’re having. I keep him body clipped year round to keep him comfortable, but since he’s so young, I figured some supplementation couldn’t do anything but benefit him. I’ve picked out a good electrolyte, but I was also reading up on E-SE-Mag and how it helps with sore muscle problems and also muscle development. Also, I read about Metaboleeze and how it delays the onset of fatigue in intensely worked horses and also how it positively impacts horses prone to tying up. My question is, should I put him on both E-SE-Mag and Metaboleeze (which I have no problem doing)? Or does he just need one or the other? Or should I even consider a different supplement? HELP!! Any advice/suggestions would be wonderful…I just want my boy to be comfortable, healthy, and happy! Thank you for your time and I look forward to hearing back from you. – DW, Georgia

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Dear DW,

As someone who has owned not one but two horses that “tie up” and for completely different reasons, I can certainly understand your concern and confusion. Let’s review what we know about “tying up” or exertional rhabdomyolysis, then provide you with some specific advice to help your horse, Liam.

Exertional rhabdomyolysis (ER) literally means muscle breakdown associated with exercise. The muscle stiffness and pain associated with this breakdown can be mild (slight shortening of stride), moderate (cramping of hindquarters or reluctance to move) or severe (laying down or going into shock). Exertional rhabdomyolysis has several names—tying up, Monday Morning Sickness, azoturia, and others—and comes in several forms. There’s sporadic ER, where a horse only ties up once in a while because of a temporary problem in muscle cells caused by fatigue, heat exhaustion, lack of fitness, or electrolyte imbalance. This type of ER can occur in any breed, gender or age. Then there’s chronic or recurrent ER, where a horse ties up repeatedly. This form has a genetic component to it. Specifically, certain lines of thoroughbreds, standardbreds, and Arabians have an inherited problem in the way muscle cells use calcium. Note: neither type is due to lactic acid build-up, which is what people used to assume caused tying up.

More recently, another form of tying up has been identified in quarter horses, warmbloods, and draft horses. Named Polysaccharide Storage Myopathy or PSSM, it can look like a typical case of exertional rhabdomyolysis or cause the horse to show other, vague signs such as difficulty backing, picking up the hind legs, collecting or striking off at the canter in warmbloods; muscle wasting and shivers-like movement is more common in draft horses. If your horse is one of these breeds or has signs like these please read my separate entry on PSSM and contact your veterinarian.

On the other hand, if your horse is not one of these breeds and only had the one episode of traditional tying up, you may be dealing with a case of sporadic ER and plain ol’ fatigue. It sounds like you already have him on a better diet (including electrolytes) and better exercise program (consistent). For a hard-working horse like yours, I do like the idea of adding Vitamin E (and Selenium, as long as his hay and grain aren’t already high in this mineral).Vitamin E and Selenium are both antioxidants that partner to reduce the oxidative stress created with heavy exercise. If you have your horse on a well-designed electrolyte, he may not need the additional Magnesium, as it may be included.

You also ask about Chromium. Unfortunately, the research is still out on Chromium as a muscle supplement. Some studies show it benefits horses in training and some don’t. We do know that it plays a role in insulin, glucose and fat metabolism, and therefore may cause an increase in lean muscle mass and an increase in time to fatigue by lowering the production of lactic acid. As long as your horse does not have PSSM, there should be no harm in supplementing with Chromium. If you’re willing to explore some other ingredients to help your horse optimize his performance, here are some additional ideas:

I strongly recommend you try these ingredients one at a time so that you know which ones work and which don’t. And I would give each at least 30 days if not 90 days to show results. Also, if you haven’t already, please include your veterinarian in your horse’s diet, exercise and supplement plan. If your horse begins to tie up more frequently, falling into the recurrent ER category, you will need to have your veterinarian perform some diagnostic testing to determine the cause and identify a solution. Good luck and happy eventing!