Feeding To Prevent 'Tying Up'

by Dr Nerida Richards - Equilize Horse Nutrition Pty Ltd

Tying up is a painful condition for a horse and a frustrating one for you as an owner. Symptoms can range from severe muscle pain and distress, apparent colic, excessive sweating, elevated heart and respiration rates, a stiff gait, muscle tremors and a reluctance to move to more mild and elusive symptoms, which just involve the horse feeling stiff, lazy or slightly lame.

Whether your horse suffers with severe tying up or a mild form, it will limit your horse’s performance and sense of well being, so the more you do to reduce the frequency and severity of bouts of tying up, the better your horse’s performance and health will be. Nutrition plays a major role in both causing and preventing tying up. This article will give you a better understanding of how you can use nutrition to manage this disease.

What is tying up?

Tying up, also called ‘exertional rhabdomyolysis’ is a group of diseases that cause muscle damage and pain during and immediately following exercise. There are two main forms of tying up; polysaccharide storage myopathy (PSSM) which most commonly affects quarter horses, draft breeds and warmbloods; and recurrent exertional rhabdomyolysis (RER) which most commonly affects thoroughbreds as well as standardbreds and possibly arabians.

Horses affected by PSSM store abnormally high levels of glycogen in their muscles. These horses also accumulate abnormal amylase-resistant polysaccharide in their fast twitch muscle fibres. Horses with PSSM appear to have no problem utilising the glycogen they have stored in their muscles when exercising. So why the storage of abnormally high levels of muscle glycogen causes muscle damage is still unknown. Recently a mutation in the gene for the skeletal muscle glycogen synthase enzyme (GYS1) has been identified as the primary cause of PSSM in quarter horses, draft horses and their crosses.

Horses affected by RER do not accumulate high concentrations of muscle glycogen, however they tend to exhibit abnormal and excessive muscle contractions, likely due to a heritable defect in calcium regulation within their cells. RER is often triggered by exercise and excitement and it is well recognised that young fillies and horses with a nervous disposition are often most often affected.

Dietary management of horses with tying up

Both forms of tying up benefit from close dietary management. Following are five rules you should follow to formulate diets for horses that tie-up:

Rule 1 – Watch sugar and starch intake

Diets high in sugars and starch aggravate both forms of tying up so monitoring and controlling an affected horse’s intake closely helps to manage the disease.

For horses with the PSSM form of tying up, all high sugar/high starch feeds should be avoided. PSSM horses should never be fed cereal grains (oats, corn, barley, wheat and rice), cereal grain by-products (bran, pollard and millrun) or any feed containing these ingredients. Molasses and feeds containing molasses should also be avoided. Some forages including oaten hay and chaff, wheaten hay and chaff and ryegrass pasture and hay are also very high in sugars and where possible should not be fed to horses prone to PSSM. When searching for feeds that are suitable for horses with PSSM, look for feeds with a total sugar and starch content (also called non-structural carbohydrate content) of less than 12%.

For horses affected by the RER form of tying up, you should try to keep the amount of energy supplied by these high sugar, high starch feeds to 20% or less of the total digestible energy intake.

High energy fibres like lupin hulls, sugarbeet pulp, copra meal and soybean hulls can be used as high energy, but low sugar, low starch alternatives to cereal grains in diets for horses that tie up.

Rule 2 – Use oil to supply energy in the diet

Current recommendations suggest that to reduce the incidence and severity of tying up, horses with PSSM should receive 13% or more of their daily digestible energy intake as oil, while horses with RER on high energy diets (for example thoroughbreds in race training) should be receiving 20 to 25% of their daily digestible energy intake as oil or high fat feeds like rice bran.

When feeding large amounts of oil you should keep in mind the omega 3 and omega 6 levels in the diet. If you use oils like corn or sunflower oil as the main oil in the diet, consider adding some flax/linseed or a specialised omega 3 oil to balance omega 3 and omega 6 intakes. With these levels of oil, care must also be taken to introduce it to the diet gradually to allow time for the horse and its gut to adapt to that level of oil feeding.

Rule 3 – Feed a balanced diet with electrolyte and antioxidant requirements met

Care should be taken to ensure the diet you are feeding is balanced and importantly that requirements for the electrolyte minerals sodium, chloride, potassium and magnesium and requirements for the antioxidants selenium and vitamin E are met. Avoiding very high levels of protein is also a good idea.

Rule 4 – Avoid oats

Oats seem to trigger the RER form of tying up in horses and particularly fillies more frequently than other grains (and we don’t know why). So for horses with RER that are still receiving some grain in their diet, use cooked corn, barley, rice or other grains you might have access to in place of oats. As discussed above, horses with the PSSM form of tying up should never be fed oats or any other type of cereal grain.

Rule 5 – Reduce or remove the grains and high energy fibre components from the diet on days off

Horses fed their full ration on rest days seem to be more likely to be affected by tying up once they resume work, so on rest days, the grain and high energy fibre portions of the diet should be reduced by half or more depending on the individual horse. You should increase the horse’s allocation of hay or amount of turn-out time to compensate for the feed you have taken out of their diet on rest days. If your horse is prone to gaining too much weight, you should also reduce the amount of oil fed on rest days.

Combine good feeding with good management

A well balanced diet containing the right amount of energy from fibre, starch and oil with all requirements for vitamins and minerals being met is only part of the puzzle for effectively managing both PSSM and RER forms of tying up.

Horses that suffer with tying up need to undergo a regular exercise program. Care must be taken to ensure horses are allowed to gradually build up fitness and horses should never be exerted beyond their level of fitness. Prolonged periods of stall confinement should be avoided, with horses that tie-up being better off housed in larger pastures or yards so they can move around freely.

Rest days need to be managed carefully. While these horses certainly do need some time off to be horses, they should never be fully box rested, but instead should be walked or turned out to pasture for voluntary exercise on these days.

Nervous horses that are prone to RER should be managed to keep their stress levels down. Always housing them with a buddy, allowing them plenty of turn-out time, feeding them first and maintaining as regular a daily routine as possible are a few things that might help.

Avoiding the knots

Following good dietary management by minimising sugar and starch intake, providing 13 to 25% of daily energy intakes as oil or high fat feeds, meeting all essential vitamin and mineral requirements including those for electrolytes and antioxidants and providing a regular exercise routine that remains within the horse’s level of fitness will all help to keep your tying up prone horses muscles ... untied.

 

Pryde’s EasiSport or Pryde’s EasiFibre are the perfect high fibre and non-grain feeds for horses with the PSSM form of tying up. Both contain less than 10% sugar and starch.

For horses with RER, Pryde’s ReBuild, a high fat, high energy supplement fortified with organic selenium and vitamin E makes an excellent contribution to the diet while Pryde’s EasiOil, a cold pressed canola oil is perfect for boosting the oil intake for horses prone to PSSM and RER.

For information on these feeds and help with how to use them for the best results with a horse prone to tying up, contact Pryde’s EasiFeed on 1300 732 267, email info@prydes.com.au or go to the website http://prydes.com.au/.