Fig. 10.1. Poor hoof balance.

Fig. 10.2. Careful examination of the foot.

Fig. 10.3. Pus being drained from the foot with a hoof knife.

Most abscesses in the foot are not related to shoeing, and in fact are more common in the unshod horse. The initial penetration often goes unrecorded, or the infection may be from haematogenous spread. Pus builds up between either the wall or the sole of the hard hoof and the underlying soft tissue. The pain is intense and is relieved only by releasing it with a hoof knife or by the pus breaking out above the coronary band. A classic history of an untreated horse would be lameness progressing in severity over 72 h and then suddenly improving. If the point where the pus is escaping can be found then the point of penetration will be directly below it. Ideally, a hole should be made in the sole. Sterile saline can then be irrigated into one hole and will flow out of the other. Both holes should be kept open to allow the soft tissue to heal within. If pus is allowed to build up again pain will return and the degree of lameness will increase. Therefore, it is advisable that a poultice is applied until healing is completed. The horse can be shod when the infection has dried up. NSAIDs can be given to reduce the pain. Once again, the horse must be protected against tetanus.

Clinicians should always be on their guard to detect serious foot penetrations. These may cause articular sepsis of the navicular bursa, the distal interphalangeal joint or involve the deep digital flexor tendon sheath. If the penetration is in the frog or the sulci the path of the penetration will be very difficult to follow. The whole foot will be very painful so hoof testers are not very helpful. Because of the pain strong sedation will be required, or even an abaxial sesamoid block. In the chronic situation it is important to debride all the affected tissue and then poultice the foot to allow continual drainage. This will occur for several weeks if there has been damage to the pedal bone. If there has been synovial penetration radical debridement is required. This can be performed with a general anaesthetic and an arthroscope. However, in field conditions a cure can be effected eventually by radical drainage. This operation is called a ‘street nail’ procedure. Welfare here is very important; high doses of NSAIDs will be necessary.

A benign but locally invasive tumour, keratoma is rare. Its initial manifestation will be seen as ‘pus in the foot’. The observant clinician will notice the white disc of abnormal horn. Once the pressure of the pus has been relieved the lameness will stop, although it will soon recur. Radical treatment is required to remove the wall of the hoof lying over the fat, worm-shaped tumour running up towards the coronary band. This has to be removed in total or recurrence will occur. The hole in the hoof must be packed with gauze soaked in iodine. The hole regenerates very quickly. The condition following radical removal carries a good prognosis.

Laminitis is extremely complex, not only in its aetiology but also in its pathology. The classic cause in horses – and more commonly in ponies – is too much rich, green grass. Grass that is itself under stress, i.e. when the nights are cold but the days are hot, is more likely to bring on an attack of laminitis. There will be a higher level of fructans in the grass. Animals become overweight, with a rock-hard crest of fat and suddenly become acutely lame. This can occur in all four legs, but much more commonly in only the front legs. The animal will adopt a classical laminitic stance, leaning backwards and trying to take as much weight on its hind legs as possible. It will be very reluctant to move. However, if it is on soft ground it will move better once it has got started. This accounts for the old-fashioned treatment which was to make the animal work. This should not be done, however, as it is not only cruel but also it bruises the feet and makes the condition worse. Having stated this if the owner thinks that the pony or horse is about to get laminitis then exercise on soft ground is beneficial; animals being worked consistently rarely get laminitis. If a case is suspected the animal should immediately be taken away from any access to grass. In severe cases of laminitis the animal may well lie down; this is good and should be encouraged.

Sadly, in neglected cases clinicians will observe that the pedal bone has penetrated the sole. In these cases prompt euthanasia is advised. In other cases, particularly in heavy horses or cob types, the pedal bone will sink within the hoof capsule. This can be perceived by pushing a finger into the groove that will have appeared at the coronary band: this action will be acutely painful for the horse.

Acute laminitic cases should be treated as an emergency. As stated above, the diet must immediately be adjusted to avoid hard food and grass. The surface on which the animal is standing is also very important. Sand or a very deep bed of shavings are both recommended; straw is less suitable, since not only will the horse eat it and may then get an impaction, but also the straw may be scraped round by the horse until it is then standing on bare concrete. Deep manure might be considered, but it should be avoided as it tends to soften the feet excessively and may bring on other conditions (see thrush, above). Concrete or very compact earth are the worst possible surfaces: these should be covered with rubber matting. If this is not possible the feet should be covered with a clog of thick polystyrene. Another action which might be suggested is to apply ‘lily pads’, which are pieces of hard rubber approximately the same size as the frog. They should be taped on to the frog with gutter tape to apply ‘frog pressure’.

There is still an ongoing debate on what to do about shoes. One school of thought suggests that you leave the shoes in place, as they are at least providing some support. It is certain that removing shoes will be very painful for an acute laminitic. It is also certain that it will be impossible to replace the shoes. Another school of thought suggests you remove the shoes so that the animal can be more comfortable taking weight on its soles rather than on the walls of the feet. When the animal has become more stabilized, heart bar shoes may be fitted to apply frog pressure. These may be either solid-fixed heart bar shoes or more sophisticated adjustable shoes, the latter being capable of having more pressure applied by being tightened up twice a week. There are also modern malleable materials which can be fashioned to the shape of the hoof to give the horse more comfort. Obviously, once the initial acute pain is controlled, the feet will need to be trimmed by a skilled farrier. The toes should be radically shortened to try to make the angle of the hoof conform to the angle of the pedal bone. A skilled farrier will probably be able to do this by eye. However, a lateral radiograph will be very helpful here.

Donkeys, like horses, may become laminitic for a variety of reasons, but the most common are either too much lush grass or grain overload. Donkeys will also suffer laminitis as a result of Cushing’s disease. It is very important that donkeys are not starved, as this may result in hyperlipaemia, which should be avoided at all costs.