FOR SOME this has been the driest start to a summer for more than 50 years and it is starting to take its toll on horses of all types.

There has been a drastic rise in the incidence of lameness, increasing numbers of horses with respiratory disease, and some dramatic cases of sunburn.

The appearance of coughs and ‘snots’ at this time of year can be puzzling – they certainly can’t be blamed on inclement weather. The development of ‘summer colds’ can be related to several factors, the first being the fact that hay stocks have become extremely dusty. Due to the high ambient temperatures, even haylage becomes dry and dusty within 24-48 hours of opening.

We are seeing new cases of allergic respiratory disease (COPD or recurrent airway obstruction) in stabled horses, as well as horses in which the dust is acting as an irritant leading to secondary bacterial infections of the upper airways. Soaking hay and haylage will help reduce the dust burden and alleviate symptoms. Many cases have required additional treatment with steroid inhalers – identical to those used by human asthmatics – and antibiotics where there is evidence of bacterial infection.

Stable ventilation, or rather a lack of it, can also contribute to respiratory disease. Opening doors and windows, plus judicious use of fans, is essential to promote air flow, reduce dust burdens and lessen the risk of pathogenic viruses and bacteria being spread between horses. Warm temperatures and high humidity also mean that these organisms survive longer in the atmosphere than when it is colder and less humid.

A third, and critical, factor in some cases of respiratory disease has been travelling to distant competitions. It has not been clear if these horses have been exposed to infections – such as equine herpes virus – that are rare in Scotland, or whether the stress of travelling in hot, humid conditions has played a role in impairing their immune response to viruses and bacteria that would normally be shrugged off without a break in training.

Summer colds aside, it has been lame horses that have occupied most of our attention over the past two months. The unusually hard going on show grounds and cross country courses has brought the prospect of cracked hooves, bruised soles, puffy joints and windgalls. We have seen all of these, plus horses with traumatic laminitis and others that are sore in multiple limbs and best described as being ‘jarred up’.

Working and competing on artificial surfaces has also not been without problems. Many arenas covered with woodchips or sand have become very dry and deep; conditions that are associated with an increased likelihood of injury to the flexor tendons and suspensory ligaments.

So, with the dry spell set to continue, what can be done to lessen the chances of orthopaedic injuries? Aside from avoiding the hardest ground and deepest arenas, the answer lays in working to reduce concussion through the lower limbs and removing as much heat as possible from the limbs after exercise.

The shape, conformation and horn quality of the hooves is critical. Long toes, short heels and flat soles all conspire to reduce the ability of the foot to cushion the effects of hard ground. Long toes can be particularly problematic since they increase the tension on the laminae – which attach the pedal bone to the hoof wall – during the break-over phase of the stride. Subsequent tearing of these laminae results in what is referred to as traumatic (or mechanical) laminitis.

Trimming the toes and using a square or rolled-toe shoe will reduce the break-over point and protect against tearing of the laminae. Bar shoes with a slightly raised heel also offer support to the structures in the heel of the foot, allowing the digital cushion beneath the frog to work more effectively as a shock-absorber.

Flat or thin soles are associated with foot pain due to bruising of the tissues beneath the sole. Using a wide-webbed shoe or fitting a rubber, silicon or leather pad under the shoe can help prevent this problem. Alternatively, the surface of the sole can be covered with a strong but flexible filler called Sole-Guard, which was used to great effect last summer. The Sole-Guard stays in place for up to six weeks and can be used with or without shoes, offering comfort to barefoot horses that need additional support.

Other foot-related factors that contribute to concussive injuries include dry horn quality, small or boxy upright hooves, and inappropriate use of studs. Efforts should be made to keep moisture within the hooves by regular application of oils, which will allow the horn to retain its elasticity and shock absorbency as well as guarding against the appearance of cracks.

Small, boxy or upright feet increase the risk of concussive-related injuries for the simple reason that the weight of the horse and the forces associated with movement are transferred through a smaller surface area. There is no simple fix for such problems and it will take all the skill and patience of your farrier to encourage the growth of hooves of more appropriate size and shape.

The use of studs is, arguably, one of the most debated issues in lorry parks and stables at events up and down the country. Unfortunately there has been little scientific study into the rights and wrongs of studding and what follows are my own thoughts on the matter. It is about finding a balance between securing grip, thereby maintaining the horse’s balance and rhythm, and not putting too much pressure up through the heels of the foot.

The available research indicates that turf is the best surface for horses to work on but the presence of dew early in the morning and moisture during humid days can make the surface slippery, even where the ground appears firm. For this reason my preference is to always use studs when competing on grass.

But I was caught out last week at Oatridge horse trials when I decided not to put studs in for the dressage – the going was firm with a good covering of grass and Hannah’s horse Molly warmed up without hint of a slip. It was a decision that I regretted for the rest of the day as, during the first canter transition, Molly’s lead leg gave way and it took Hannah some time to regain the horse’s balance. Needless to say it was my fault they got a six and not a seven for that movement!

On firm ground I tend to use small pointed studs in the front shoes, in both the lateral (outside) and medial (inside) parts of the shoe, with two slightly larger studs in each hind shoe. I know that many people chose not to put studs in the medial part of the shoe for fear that these cause injury to the opposite limb. But I prefer to have the foot balanced by two studs, especially when the going is hard. I am also anxious to ensure that, once the studs are in, the horse avoids walking on tarmac or concrete.

It is not just in the foot that concussive forces can cause problems; joints in the lower leg can become painful and swollen, with pain on flexion of the limb. Icing the knee, hock, fetlock and pastern joints with cooling wraps, gels or ice packs soon after competing can help prevent inflammation of these structures. Refrigerant units, such as the Zamar, are extremely effective as they also apply massaging pressure to the joints.

Careful examination of the legs, coupled with trotting the horse up the next morning, is recommended to identify any problems that arise following a competition. Dietary joint supplements, non-steroidal anti-inflammatory drugs like Bute and Danilon, and injectable joint agents such as Hyonate and Adequan can all help prevent and manage joint pain associated with excessive concussion.

In contrast to concussive injuries, which tend to be mild and relatively short-lived, damage to tendons and ligaments can be catastrophic.

Little can be done to support these structures during competition – the boots that we apply to the lower limb are simply there to protect against direct trauma from a fence or foot.

Tendon and ligament injuries are caused by excessive stretching, usually because the limb becomes overloaded.

Research has identified two key factors that increase the risk of such injuries; these are the nature of the surface that the horse is working on and excessive heating, particularly of the flexor tendons.

Studies in racehorses have shown that waxed surfaces provide for a more gradual and less severe loading of the superficial digital flexor tendon, when compared with a crushed sand surface.

Similarly, the risk of suspensory ligament injury in dressage horses has been associated with working on deep, sand arenas.

Retention of heat within tendons following exercise is believed to cause thermal damage to tendon tissue, increasing the likelihood of subsequent injury.

In a galloping horse, the core temperature of flexor tendons reaches as high as 45oC and there are, on the market, several tendon boots with ventilation built-in.

My own preference is to use relatively lightweight protective exercise boots, which are removed immediately the horse has finished and cooling wraps applied.

These are replaced every 10-15 minutes until the tendons are cool to the touch. Ice packs and cooling gels can be used in just the same way and a small, portable refrigerant unit has been developed by Zamar – it is on my wish list!