EQUINE VETERINARY EDUCATION / AE / SEPTEMBER 2017


509


a)


b)


c)


Fig 14: Acute diaphyseal fracture of the left humerus; (a) dysfunctional limb with ‘dropped elbow’ posture; (b) swelling produced by haemorrhage; (c) shortened brachial segment demonstrated by fingers on the lateral tuberosity of the humerus and olecranon.


fractures. This is a poor prognostic sign and, since the majority of horses with complete, displaced fractures that occur on the racecourse cannot currently be saved, swift humane destruction is indicated (Hill 2003a; Dyson 2011). Control of pain is difficult in such horses and rarely satisfactory. Crepitus may be palpable and/or audible. The elbow and carpus cannot be fixed, but in the peracute phase it is difficult to be confident whether this is a result of disarming the triceps apparatus and/or due to laceration of the radial nerve by the displaced fracture. If the horse is recumbent with the injured limb uppermost


then a clinical diagnosis can usually be established without the need to get the horse to its feet. If this limb is on the underside, then turning the horse may be necessary in order to establish the reason for recumbency. In most circumstances this is readily achieved by attaching ropes to the underside fore- and hindlimbs. However, if there is any suspicion of fracture in either of these, then use of the upper limbs also is recommended. As the horse initially is raised, the loss of skeletal continuity in the underside limb may immediately be apparent. All authors agree that there are no benefits to be gained


from attempting temporary immobilisation of humeral fractures (Bramlage 1983, 1996; Furst 2006; Mudge and Bramlage 2007). Limb mechanics preclude effective immobilisation and the surrounding muscle masses protect the fractured bone. Fractures of the lateral tuberosity of the humerus that


extend distally to involve varying amounts of the cranial lateral diaphysis and deltoid tuberosity can result from falls in jump racing. Afflicted animals may, on rising, be non- or minimally weightbearing. Crepitus may be evident over the lateral proximal humerus. The amount of haemorrhage is variable but almost always less than that seen with the diaphyseal fractures and it is restricted to the fracture area. There is no brachial shortening and within a few minutes the horse usually will tentatively load the limb though protraction will be restricted. In contrast to complete diaphyseal fractures these often are amenable to removal or repair with return of


function (Mez et al. 2007). There are no necessary or contributory temporary immobilisation techniques. Most racetrack evaluations of humeral fractures are


clinical only. If adequate radiographic facilities are available at or close to the racecourse, then it is appropriate for these to be utilised. Ultrasonography can be readily performed in racecourse clinical facilities and may confirm osseous discontinuity and aid in fracture differentiation.


Fractures of the scapula Fractures of the scapula can result from stress overload in flat racehorses or from falls in jump racing (Adams 1996; Dyson 2011). The latter most commonly involve the supraglenoid tubercle. After a short initial period of nonweightbearing, horses with fractures of the supraglenoid tubercle will load the limb, although, as the origin of biceps brachii is lost, the cranial phase to the stride (protraction) is severely reduced. External support is counterproductive, simply increasing limb load. Some, but not all, horses will be helped by assistance with limb protraction/extension from a rope passed around the pastern. This is used to reduce some of the effort needed to protract the leg; pull/lift should be applied in a steady, controlled manner once the limb breaks over. Complete fractures of the neck and body of the scapula


commonly displace and override. Trauma to axial neurovascular elements iscommon and haemorrhagic swelling can rapidly develop. Afflicted horses are non- or minimally weightbearing and usually are markedly distressed with minimal relief from analgesics. Viewed from the front, the swelling can appear to result in abaxial displacement of the scapula from the thoracic wall (Fig 15a). The scapulohumeral joint (usually visualised by the lateral tuberosity of the humerus) may appear ventrally displaced; this is not of itself pathognomonic, but shortening of the scapula length (assessed as the distance from the proximal margin of the scapula to the proximal margin of the lateral tuberosity of the humerus) is highly suggestive of a complete, displaced fracture (Fig 15b). If a confident diagnosis cannot be made on clinical grounds, then it is appropriate to move the horse on an


© 2016 EVJ Ltd


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88