From YourSITE.com
Called, amongst others, Monday Morning Disease, Azoturia, Tying up and Exertional Myopathy
By Spillers
May 21, 2006 - 7:19:00 AM
'Tying Up': What it means in the 21st century
1. Introduction
Recognise the signs? Out on exercise, suddenly your horse is reluctant to move forward, starts to take stiff, short strides and comes to a halt - sweating perhaps more than normal - a classic scenario for an episode of tying up.
It's not that simple though - the condition is complex in itself, with multiple factors precipitating the onset of an episode, which may take many forms, and there are a multitude of products claiming to help manage the condition.
In all, in these modern times it is perhaps more complicated than ever to understand and manage your horse to reduce the risk of an episode of tying up occurring in your yard.
If anyone is qualified to write on the subject, it is SPILLERS. Director of Science, Dr Pat Harris, based at the WALTHAM Centre for Pet Nutrition, is an acknowledged worldwide expert on the subject. In addition the company is the Official Supplier of Nutrition to the British Equestrian Teams, and its front line nutritionists give good practical feed and nutrition advice to customers. SPILLERS also pioneered the use of high fibre, low starch feeds in the management of horses with this distressing condition.
In this feature, the SPILLERS team, of Dr Harris, Ruth Bishop (Technical Director), Emma Bines and Sarah Hill (Competition Unit Nutritionists) cover all aspects of the condition, and invite you to participate in a survey on the condition.
2. A Brief history of the disease
It's been called, amongst others, Monday Morning Disease, Azoturia, Tying up and Exertional Myopathy; below is a quick précis of the development of our knowledge:
Monday Morning Disease: The condition known in draft horses in the late 19th century. Given the day off on Sundays without a reduction in their oats, some would collapse with severe muscle damage, and on occasions actually die, when put back into work on the Monday.
Azoturia (named because products of protein breakdown were found in the urine) was reproduced in the 1930s by feeding very large amounts of molasses and then exercising. The theory being that excessive muscle glycogen (a storage form of glucose) was deposited during periods of rest which was quickly converted to excessive lactic acid during exercise- effectively 'poisoning' the muscle cells. This theory lasted for 50 years.
In the late 1980s, the lactic acid theory went out of favour as most horses that suffered from the condition did not have higher levels of lactic acid in their plasma or muscle than non-affected similarly exercised horses. At this time 'Tying up' was typically the name of choice, named after the most common clinical sign: an inability to move.
By the late 1990s, it was acknowledged that there were several different causes of the condition and that it could occur in non-exerted horses. Therefore, the term the Equine Rhabdomyolysis (meaning literally inflammation of the muscles) Syndrome, (ERS), to reflect the multifactorial nature of the condition, was increasingly used. In particular two distinct subgroups were identified which may have a genetic basis: Recurrent Exertional Rhabdomyolysis (RER) and Polysaccharide Storage Myopathy (PSSM).
3. Clinical signs
ERS affects the muscles so that they cannot function as normal. This results in a wide range of possible signs from failing to lengthen when asked, to the more typical animal that is unwilling or cannot move, or more rarely an animal that actually goes down and cannot get back up.
During an episode the affected animal will often be in some pain and distress although this tends to vary with the individual and the extent of the damage. The muscles of the hind limbs are the most severely affected but in a few individuals the forelimbs may also be involved. Muscles may be swollen and/or painful to touch but this is not always the case especially in the more mild cases. The affected area is normally quite generalised over one or more muscle groups compared with the more localised pain resulting from pulled or strained muscles.
4. Diagnosis
A provisional diagnosis is based on clinical history, clinical signs and then confirmed by blood test: monitoring plasma muscle enzyme activities (Creatine Kinase: CK and Aspartate Amino Transferase: AST). Sufferers from PSSM can be identified by means of a muscle biopsy.
In recurrent cases it may be worth determining the indiviudal horse's electrolyte status by means of the Fractional Electrolyte Excretion Test (FE) , which involves the collection and analysis of blood and urine in collaboration with your Veterinary Surgeon.
5. What causes ERS?
We believe that most sufferers have an underlying susceptibility to the condition, which may then be triggered by one or more factors, usually including exercise, resulting under certain circumstances in the clinical signs.
Underlying susceptibility
(Possible abnormalities could be metabolic, biochemical,
hormonal,nutritional, infectious, or circulatory)
Contributory Triggering Factors
(Include:- Temperament, Management, nutrition, infection, hormonal imbalance, time of year, weather etc.)
Final 'triggering' factor
Most commonly:
CLINICAL SIGNS
The underlying factor or factors as well as the triggering factors differ between groups of sufferers. Sporadic episodes often have significant trigger factors such as management or nutrition that override an otherwise mostly robust horse. Animals suffering frequent episodes may be more likely to have a more prominent underlying susceptibility such as RER and PSSM. But nutrition still plays a role as discussed below.
Recurrent Exertional Rhabdomyolysis (RER)
*Due to an abnormality in the process of muscle contraction; may be inherited.
*Found mainly in Thoroughbreds, Standardbreds and Arabians, especially young nervous fillies.
*Affected animals often experience very frequent episodes with persistent AST elevations.
*Triggering factors can include training at a gallop but restraining the horse from reaching top-speed, prolonged periods of box rest, high grain diets, excitement and the presence of a concurrent lameness.
*Confirmation of the diagnosis involves whole intercostal muscle biopsies and intensive laboratory tests and therefore is rarely undertaken
Polysaccharide Storage Myopathy (PSSM)
*Caused by a defect in the way that glucose is handled and stored in the muscle
*Affected animals have high levels of glycogen (the storage form of glucose) and a non-available abnormal glucose storage compound (a polysaccharide) in their muscles;
*Mainly found in Quarter horses and related breeds (may be inherited), warmbloods as well as a few Arabians, standardbreds and thoroughbreds.
*Trigger factors include being rested for a few days prior to exercise, infection and most importantly the diet.
*Horses tend to have a more calm temperament than RER horses and often have persistent elevations of Creatine Kinase (CK) without these always being associated with clinical signs.
6. Can ERS be prevented?
There are no guarantees that preventative management will stop further episodes from occurring. However, appropriate management may help to reduce the likelihood or frequency of future episodes.
Some useful management guidelines are:
1. Keep a record of the events up to and after an episode of ERS
2. If certain trigger factors (such as not reducing feed on days of rest; prolonged periods of stable rest; overexertion, being in season, using the horse walker, restraining from reaching top speed when galloping etc.) can be linked to episodes then avoid these wherever possible.
3.'Stress' is often a contributing triggering factor, and if this is a possibility in a particular horse, seek to minimise it, for example by :
a. If the horse is quieter being ridden out in company then don't ride out alone;
b. If the horse gets disturbed at feed time, then feed first;
c. Keep to the established routine as far as possible.
4. Dietary tips
a. Cut concentrate feed on days off or during periods when laid off (see below).
b. Salt and electrolytes: Salt should be provided daily at between ½ - 2oz (for a typical 500kg horse) depending on work rate, sweating etc. A reduction in the frequency of episodes or even prevention may be effected by appropriate electrolyte (calcium, magnesium, sodium and potassium) supplementation. It is therefore very important to try and ensure that the core diet provides a sufficient intake of these electrolytes in an adequate and balanced manner. Although even on such a diet certain sufferers may have an individual problem, which can only be detected via an FE test and then individually corrected.
c. Vitamin E and selenium: Both help to protect against cellular damage and appropriate intakes are of importance. However, it is unlikely that their deficiency is a primary cause of ERS. Recommended levels are Vitamin E around 1600 -2000iu per day for a 500kg horse (more if in hard work), plus an extra 100 iu per 100ml (glug) of oil added above this. Selenium should be around 2-2.5 mg/day.
d. Fibre: keep fibre levels high, either through forage or fibre containing feeds. Avoid turnout onto lush fast growing pastures but prolonged daily periods out in a sparse paddock is often beneficial.
e. Other energy sources: as a general rule of thumb, keep starch and sugar intakes as low as possible, and rely on fibre and oil for energy. For PSSM horses in particular, it has been recommended that they are not fed any cereal starch at all and that their sugar intake in general is kept as low as possible. Oil should be supplemented at no more than 100 mg per 100kg body weight.
f. Ensure that your horse is receiving sufficient protein, vitamins and minerals, for its work load, from its basal diet (especially if additional oil is being beneficially used as an non- starch energy source) - if not then consider adding an appropriate vitamin and mineral mix.
7. Managing an episode
Always contact your Veterinary surgeon for advice with any episode but some practical tips are given below:-
1. Initially
a. Avoid forced walking and if possible get the Vet to treat the horse where it has suffered the episode.
b. In the more severe cases if transportation is needed then ideally a lorry, rather than a trailer (providing that the ramp is not too steep), should be used.
c. Regardless of the mode of transport the horse must be safely supported, throughout transportation, in such a way that further muscular effort is kept to a minimum.
d. Put in a clean dry (so that you can tell that urination has occurred) stable away from draughts.
e. Provide grass hay and if necessary later on a small meal of a high fibre pellet - which can be soaked so that it forms a moist gruel.
2. Proceed to the next stage when
a. The affected animal has been moving freely around the stable for several hours.
b. There are no signs of pain when the muscles are felt and the horse does not resent (anymore than normal) any palpation.
c. The urine is not discoloured by myoglobin (a reddish brown pigmenting protein released from damaged muscle).
d. If in any doubt about when to proceed then contact your Vet
3. When able to proceed
a. Turn out into a small field/indoor school (rather than start in-hand or ridden exercise) but avoid 'lush' pastures (treat in a similar way to a laminitic) and avoid getting cold.
b. Encourage 'gentle' movement in field (e.g. turn out with a quiet known companion- put the feed and water at opposite ends of the area etc).
c. If your horse is very excitable it may be worth discussing this first with your Vet (although it is rare that sedation is needed).
4. Starting work again
a. In mild cases can start after only 2-3 days in the field unless directed otherwise by your Vet. In more severe, or repeat cases, wait until the muscle enzyme activities have returned to within acceptable limits
b. Especially in the initial stages of a return to work avoid lungeing, horse walkers, or work in tight circles, as well as hill work.
c. Slowly increase the intensity and duration of the exercise and if your horse misbehaves on its own or in company, ride alone or with others as appropriate.
d. Daily exercise or turnout often seems to be valuable - again, avoid 'lush' pastures.
e. Keep to regular daily exercise, avoiding the use of horse walkers or lungeing
f. If daily exercise is not possible turn out for as long as possible on rest days and reduce any complementary feed intake (half) from the evening before the day of rest until the evening afterwards.
Owners who would like further individual advice are requested to contact their Veterinary surgeon who, if appropriate, will be able to contact Pat Harris directly.
8. Practical feeding of the event horse that suffer from ERS.
Emma Bines and Sarah Hill both work as nutritionists for the SPILLERS Competition Unit, and together with Ruth Bishop, Technical Director, they co-ordinate the nutrition support to the riders under the World Class Start and Potential program.
Chronic tying up
Emma Bines first became interested in ERS when one of her event horses, Tagalog, tied up in the 10 minute box at her first 3 day event. Based with Charlotte Bathe at the time, Emma knew that attention had been given to every detail of her fitness and training programme, and so looked for possible causes. (Such was Emma's commitment to helping her horse that she made it the subject of her final year dissertation at University.)
The main areas which kept Tagalog free from subsequent bouts were:
1. Feed:
Increasing fibre and reducing starch levels in her diet. She received a diet of Spillers Response Slow Release Cubes, Hi Fi, corn oil and soaked hay. In addition to this she received Equivite Vitamin E & Selenium, in recognition of the high oil content of her diet, an electrolyte blend and a probiotic supplement during times of stress.
2. Diagnosis:
a. a fractional electrolyte clearance test helped to highlight problem areas and helped decide on the most appropriate supplementation regimen.
b. Monitoring muscle enzyme levels by taking regular blood tests and building up a profile to refer to. At one 3 day event, the vet even ran from point to point on speed and endurance day taking blood samples all the way! This taught us that the timings of her canter work were vital, and though initially took some juggling we did eventually hit upon the right formula.
3. Management:
a. Keeping her quarters warm at all times. She was particularly vulnerable after the steeplechase, if it was cold or wet on phase C I knew I was likely to have problems.
b. She was never lunged, following one incident at home where she tied up very badly following such exercise. Lungeing has been implicated in various other horse's case histories as well.
Sporadic ERS
Sarah Hill feels from the cases seen that many sporadic episodes do have a nutritional basis, and cites the case of an eight year old intermediate eventer, that had tied up towards the end of the season.
The horse had increasingly run up light throughout the second half of the season, and doing what they believed to be the right thing, the owner stepped up the horse's existing feed to pull the horses weight back up. The feed was increased by 2.5kg/day (from 3.5 - 6 kg per day) in the week prior to the first attack, and, also significant, the feed was high in starch.
In effect, the diet changed from one delivering 1300g of starch per day to one delivering 2200g in 6 days - an increase of nearly 70%.
Nutritionally there were a number of reasons as to the occurrence of the ERS towards the end of the season:
a. Sudden increase in the amount of competition mix and therefore starch in the diet;
b. A subsequent decrease in forage intake
c. As a result of a (prolonged) electrolyte imbalance
The recommended diet to manage the issue of maintaining weight and reducing the risk of further episodes, incorporated highly digestible fibres and oils, and minimised the amount of cereal starch in the ration. The diet (below) crucially delivered 570g starch, approximately ¼ that supplied by the problem diet, and approximately half of that supplied by the original diet.
The mineral profile of this ration delivers all the horse's requirements for the work that he is doing, including a correct Calcium:Phosphorus Ratio and adequate sodium.
Recommended Daily Diet (Intermediate eventer, full work, runs up light, has suffered from ERS in past):
10.0 kg Haylage
0.50 kg Readi Grass
4.50 kg RESPONSE Slow Release Cubes
1 Tablespoon Salt
Electrolytes (When req.)
PLEASE COMPLETE THE FOLLOWING SURVEY (one per yard) EVEN IF NO HORSES IN YOUR YARD HAVE SUFFERED FROM THE CONDITION
Tying up in Event horses - how important is it?
With your help we may be able to answer this question.
The condition of ERS (also known as Tying up, Set Fast, Azoturia, etc) appears to affect most if not all breeds of horse and at almost any age. It is therefore very important to understand how common the condition is, what may trigger off an episode as well as how to manage it.
Recent surveys have suggested that this is a very important condition for the race horse however, no one has specifically looked at the incidence in Event horses or what may be the common triggering factors in this group.
The University of Nottingham in collaboration with Dr Pat Harris MRCVS of the WALTHAM® Equine Studies Group is therefore carrying out a survey into the condition in Event horses. This is being actively supported by British Eventing.
All individual information will remain confidential, although information gathered may be collated and published to be used by British Eventing, WALTHAM® and SPILLERS® in the support of horse owners and veterinarians.
Please complete this survey electronically by visiting the University of Nottingham website at: www.nottingham.ac.uk/biosciences/ah/event_horses/
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