Endurance Riding, Part 4, Section 2

Tying Up, Thumps & Over Cooling a Horse

By Kristene Smuts

Tying Up (also known as Azutoria, Myositis, Monday Morning Sickness, Exertional Rhabdomyolysis, Setfast)

To understand what makes this condition so dangerous, you need to appreciate how the muscles, blood and kidneys work in addition to contributing dietary factors. There are two other factors not widely attributed to tying up, and they are poor saddle fit and unbalanced hooves, which we'll touch on briefly.

Studies are still being done as to exact cause of this syndrome, but several contributing factors have been identified. Remember in the previous article, protein was named as a contributing dietary factor. A sport horse which has been fed his normal ration of concentrates and has had a day or two off, may show mild signs of tying up when first being exercised. The severity of the condition varies from horse to horse and can be as wide ranging as a mild stiffness in the hindquarters to totally "freezing up", where the horse is unable to walk another step with severe sweating and obvious pain. When you're conditioning your endurance horse and you've given him his two days off, reduce his concentrates and give him adequate turn-out, allowing him to exercise himself by walking off any possible stiffness. You can even hand walk him for a kilometre or two.

Selenium and Vitamin E deficiencies are also contributing factors. By supplementing these two minerals, you'll be contributing to the prevention rather than the treatment of this condition. Before deciding to supplement, have your feed analysed - this includes your forage - to determine the amount to supplement as over feeding Selenium can build up in the system causing a toxic reaction. Vitamin E has no toxic side-effects.

The lack of Potassium and Calcium have also been named as contributing factors, so when you have your feed analysed, identify levels of these minerals as well.

The biological steps that happen when tying-up is imminent, are as follows : dehydration and electrolyte depletion causes the muscles to lose the ability to get rid of waste products like lactic acid and also hinder the absorption of electrolytes into the muscles. This results in the muscle cells shutting down, trapping the waste products inside the cells. If the damage is severe, a red pigment - myoglobin - is released into the blood which is transported to the kidneys. This pigment molecule is fairly large and in mild doses the kidneys can handle the excretion thereof, but when more of these molecules assault the kidneys, they can clog the filtration system, resulting in kidney failure and ultimately death. The excretion of the myoglobin molecules is clearly visible in the urine and are an early indication of trouble brewing. The urine will start showing up as "bloody" and in severe cases can be as dark as strong coffee. Now you know why you should study your horse's urine to become familiar with the colour and consistency!

When you're at a ride and you suspect that your horse is tying up, ask the vet to have a look and he'll be able to make an educated assessment. You need to take the whole horse into account when trying to figure out if he's tying up or if he's merely tired. A horse that is even mildly dehydrated, has lost interest in eating and drinking, looks dull and his gut sounds aren't what they should be, take a closer look at how he stands. If he's standing in a stiff stance and is either unwilling to move or when he does move is stilted, very gently feel his back and loin muscles. They'll be hard and the horse will immediately show pain. Should your horse show signs of tying up, do not move him as this may worsen the situation. Get the vet and he'll give your horse a muscle relaxant and a mild sedative. If you're in the middle of your ride, either phone back to base camp or get one of the other competitors to alert the Ride Master or vet and they'll send a box to pick you up. Under no circumstances should you try to ride back to camp - your horse's life is at stake.

Get to know the difference between tying up and mild exercise stiffness and know when to go into high alert mode. If you're unsure, rather err on the side of caution and if it turns out that it wasn't tying up, well so be it, but should you decide otherwise and your horse was tying up, you'll kick yourself all the way back to camp.

If you're at home and you suspect your horse is in trouble, call the vet and he'll be able to take a blood sample to determine the severity of the situation. When the muscle cells start shutting down, apart from the release of myoglobin, they also release two enzymes called creatine kinase and apartate aminotransferase into the blood. The higher the levels of these two enzymes, the greater the severity of your situation.

Very briefly, poor hoof balance will result in your horse compensating with his muscles which results in cramping. Poor saddle fit will result in the back and loin muscles becoming sore and tender and cause locomotion compensation in the hindquarters. Although not technically tying up, it may contribute towards it in an already compromised horse.

So, does all this mean that you can never ride your azoturia-prone horse again? No, it doesn't. All it means is that you need to manage the health of your horse more carefully. Educate yourself about feed and electrolytes, supplement properly and when you do ride out again, start slowly by walking at least for half an hour before trotting, trot again for at least half an hour before cantering.

A word of warning about restricting protein intake. Don't substitute with bran when you do cut down on the protein, as bran contains a substance called phytate which can bind dietary calcium and prevent its absorption by the gut, effectively limiting the body's supply of calcium.

Thumps (also Synchronous Diaphragmatic Flutter (SDF))

Thumps go hand-in-hand with tying up, and should be managed in the same way. It's an early indication of an exhausted horse. When a horse loses electrolytes, it depletes the system of calcium, potassium and magnesium, making the nerves hyper sensitive. A particular nerve called the phrenic nerve runs across the tip of the heart on its way to the diaphragm. As the heart beats, it triggers this nerve and the diaphragm contracts in time with the heart. It shows up first on the left side as a mild flutter, but can become so severe that you can actually hear the thumping.

Other signs to look for are a stiff gait, tense facial expression, a drooping third eye-lid, twitching or quivering muscles.

Thumps is a warning signal of a dehydrated horse and ignoring it would be to your peril.

Over Cooling a Horse

When you start to groom your horse before presenting to the vet, always start with the legs, then neck and abdomen, and only when the horse is sufficiently cool, move to the bigger back and haunch muscles. If the day is cool or a cold breeze is blowing, don't touch the big muscles and cover with a sweat sheet or a towel, letting the horse cool down on his own. If you cool the big muscles down too quickly or they catch a chill, you run the risk of cramping those muscles, mimicking tying up symptoms.

While cooling your horse down, make sure that you cool down to a point, and not beyond, where the skin is cool to the touch, otherwise you run the risk of chilling him. Don't put ice-boots on his legs immediately, wait for the tendons and ligaments to cool down sufficiently before applying the boots. Sudden cold tendons and ligaments run the risk of tearing, resulting in tendinitis or a bowed tendon. It can also result in cooling the horse down so rapidly that you run the risk of chilling the horse. Ice-boots can also mask a potential lameness problem, so wait for the legs to cool down properly before icing them.

If it's a hot day, your horse will appreciate a bath, but don't cool him down with water that is too cold. Leave the water in the sun for a bit so that the cold edge is taken off.

When cooling him down, remember this sequence - water on, scrape off, water on, scrape off, and so on, until he's sufficiently cool. If you don't scrape the water off him, all you're merely doing is adding water and letting your horse heat it up. By scraping the water off, you're scraping away the hot water, adding cool water again and scraping the hot water off, thereby cooling him more rapidly than if he was left to do it himself by merely sweating.

Part 4, Section 3