Why do horses lug? Common problems and how to treat them | Trainer Magazine | European Trainer Article Index

Apr 14

Apr 14 Why do horses lug? Common problems and how to treat them

Perhaps the most obvious cause of a horse carrying its head to one side and lugging is a mouth or tooth problem. ‘Wolf teeth’ are the rudimentary first upper premolar teeth. Not all horses get them but when present they are found in front of the cheek teeth. The wolf tooth is the most common individual tooth to cause pain because it is found exactly where the bit sits and hence most people remove them, particularly if a horse shows any sign of pain or lugging. Horses can also lug as a result of problems associated with their cheek teeth. Due to the way in which the horse grinds its food, moving its jaw from side to side, the upper cheek teeth tend to become sharp on the outside and the lower cheek teeth tend to become sharp on the inside. If teeth are left sharp for too long, they can cause A horse with a small wolf tooth (circled) and some sharp teeth (arrows). Teeth problems like these can make a horse lug known as ‘caps’) are coming loose then these should be taken out. Finally, a decision must be made as to whether it is still reasonable to continue riding the horse in a normal bit. If not, a straight rubber bit could be used or perhaps in severe cases a Hackamore or bitless bridle might be used, at least until the wounds have healed. Pain associated with a front leg can often cause a horse to lug, especially when under pressure in the final stages of a race. When a horse has a front leg problem it tends to lug away from the pain and so a horse with a left fore injury will lug to the right and vice versa. There is an endless list of problems that can cause front limb pain but with regards to causing lugging they can be grouped into new, acute injuries and long-term, chronic problems. A common example of a new, Lugging is a common problem. In some horses it occurs as a one-off event due to a new injury while in other horses it can b ecome a ‘normal’ trait. There are many possible causes of lugging but these can be broadly grouped into mouth problems, front and hind limb pain, other musculo skeletal problems, temperament/vision problems and cardiovascular or respiratory problems. By James Tate BVMS MRCVS painful wounds which make the horse favor one side of its mouth more than the other and so lug at exercise. Furthermore, the problem can develop into a vicious cycle because if a horse starts to put too much pressure on the ‘good’ side of its mouth then a wound can also form here, leaving the horse with wounds on both sides. Treatment of such problems involves addressing the mouth wounds, correcting the tooth abnormalities and taking appropriate action with regard to the horse’s bit. Mouth wounds should be flushed daily with warm, salty water and some also advocate the application of human mouth ulcer ointments on cheek wounds or creams containing corticosteroids for mouth angle cuts. With regard to the teeth, the sharp edges should be rasped smooth and if any deciduous/‘milk’ cheek teeth (otherwise acute injury is a bowed tendon, which often occurs towards the end of a race and can cause a horse to lug quite severely away from the injured leg in the final stages. The most common chronic front leg problem to cause lugging is joint pain, which often makes a horse lug in or out up the stretch depending on which leg is painful. For example, a horse with chronic left knee pain may lug out up the stretch because it is more comfortable for them to lead on their right fore. In addition, track conditions can affect the degree of lugging (for example, some horses may lug more on muddy tracks) and this lugging can also be quite noticeable at obstacles in steeplechase racing as the horse may want to take off or land on a particular leg. Hind leg pain can also cause a horse to lug; however, unlike with front leg pain, a horse with a hind leg problem generally lugs towards the side of pain – something that many people find surprising. The most common cause of lugging due to a hind leg problem is joint pain and one of the most frequent examples of a hind leg problem that causes a horse to lug is arthritis of the hock joint. This may only cause mild lameness but it can often make a horse lug quite severely, particularly towards the end of a race. While it is generally accepted that front leg pain commonly causes horses to lug away from the cause of pain and hind leg pain causes horses to lug towards the side of pain, what is less well understood is why some problems cause lugging and others do not. There are many horses with painful joints racing every day, but why do some lug and not others? Are the horses that lug in more pain than the ones that do not or are some horses simply tougher than others? Other Musculoskeletal Problems The horse’s musculoskeletal system does not simply comprise of the legs and there are several other musculoskeletal problems that can cause lugging. One of the best steeplechase horses in the world, Master Minded – two-time winner of the prestigious Group 1 Queen Mother Champion Chase at Cheltenham – had a well-publicized lugging problem recently. Having finished a disappointing third on his reappearance at Cheltenham in November 2009 while lugging right throughout, he underwent a thorough investigation that led to a ‘bone scan’ (nuclear scintigraphy). This diagnosed him with a stress fracture of his tenth rib. Having undergone an appropriate period of rest, he returned to the track successfully at Newbury in February and is now a hot favorite to make it three Champion Chases in a row at the worldfamous Cheltenham Festival in March. Of the other musculoskeletal problems that can cause lugging, the most commonly diagnosed is back pain. A horse that is lugging is often examined after it has run by a ‘back manipulator,’ chiropractor or physiotherapist who unsurprisingly diagnoses the horse with a sore back, which they then ‘correct,’ and this is blamed for the problem. However, the horse’s back is a very difficult area to assess both clinically and using x-rays or ultrasound scans, and so while it may be undeniably sore after a race, is this the primary problem or is the back soreness simply secondary to the horse lugging due to another problem? Nevertheless, in spite of this concern that back pain may be over-diagnosed, the area cannot be overlooked and there are a few serious back conditions that can cause lugging, such as a ‘kissing spine’ where a horse’s back vertebrae ‘rub’ together, or even a pelvic stress fracture. Temperament and Vision Some argue that all horses which look ungenuine and lug have a problem and that we are just incapable of finding it. Nevertheless, certain horses simply do not wish to be racehorses and a horse carrying its head to one side looking everywhere but the direction in which it is meant to be racing is a sign of lack of resolve. Excuses might be made for a few races and the lugging might be put down to the horse being ‘green’ or perhaps not liking the kickback if the horse broke slowly out of the gates. However, there comes a point when all the excuses run out and the horse is simply labeled as ungenuine and unwilling. In the wild, the horse is a ‘prey’ or ‘flight’ animal and so is designed to have a wide field of vision to see its predators early and outrun them. As a result, the horse has two large eyes each placed on the widest part of its head, giving it almost a 360-degree field of vision. It is for this reason that trainers use different types of tack to try and change the way a horse carries its head and races. Different bits can help different horses, a shadow roll can help keep a horse from holding its head too high, and headgear like blinkers can force a horse to concentrate and look straight ahead. Indeed, it is interesting how often the application of headgear can straighten a horse’s headcarriage as it prevents the horse from VETERINARY 32 TRAINERMAGAZINE.com ISSUE 16 heart rhythm that results in poor circulation and therefore the horse does not receive enough oxygen, leading to an exhausted horse that is unlikely to run in a straight line if indeed it can run at all. Respiratory problems are also well known for causing severe exhaustion, which in turn causes lugging. These respiratory problems can be split into two groups – infectious conditions such as bacterial or viral infections and laryngeal/pharyngeal conditions such as paralysis of the left side of the larynx or soft palate displacement. Horses that become exhausted due to a respiratory condition often carry their heads up high in an attempt to receive more air. Conclusion When a horse is lugging, a thorough investigation considering all of the most likely causes should be performed. First, the mouth should be checked. Then the horse’s musculoskeletal system should be assessed – is the horse lame, or are there any other signs of a musculoskeletal problem? Front leg pain generally causes a horse to lug away from the pain and hind leg pain usually causes a horse to lug towards the side of pain, while other musculoskeletal problems such as a rib fracture or a back problem are less predictable and more difficult to diagnose accurately. Could the horse be lugging due to exhaustion as a result of a cardiovascular or respiratory condition? Is there any problem with the horse’s vision or, if the horse is just ungenuine and temperamental, would the application of headgear or a different bit help? I hope that this article has given the reader some ideas for when they are next faced with this familiar problem. ■ An endoscopic image of the lar ynx of a horse suffering from dynamic laryngeal collapse. Horses with severe respiratory problems often become exhausted and lug when put under pressure due to a lack of oxygen A ‘bone scan’ (nuclear scintigraphy) image of a horse with a rib fracture lik e the one diagnosed in Master Minded, which caused him to lug badly looking behind. The famous racehorse and sire Broad Brush was racing successfully in blinkers but the decision was made before he ran in the 1986 Pennsylvania Derby that his headgear would be left off. This led to one of the most memorable races of all time as he lugged out so badly off the final turn that he ended up racing on his own up the stands rail, but still managed to win. Headgear is not the only thing that can affect a horse’s field of vision and headcarriage. For example, a horse with a visual impairment such as blindness in one eye or having a large eye scar usually has an awkward head-carriage that should not be confused with lack of resolve. There is a one-eyed filly called Barshiba racing in the UK at the moment who is now both a Group winner and a Royal Ascot winner despite carrying her head to the side to make up for the fact that she only has one eye. Cardiovascular and Respiratory Problems It is difficult to cover every possible cause of lugging but I would suggest that the majority of them have been discussed above with the exception of one category: severe exhaustion due to cardiovascular or respiratory problems. All horses are tired after a race but a horse with such a condition can suffer from severe exhaustion in the latter stages of a race – something that causes them to become distressed and lug in or out. The most common cardiovascular condition that causes severe exhaustion and lugging is atrial fibrillation. It is an irregular

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James Tate BVMS MRCVS (14 April 2010 - Issue 16)

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