Page 87 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

62 CHAPTER 1

VetBooks.ir ANCILLARY DIAGNOSTIC TESTS of equivocal radiographic findings. To a lesser extent,
ultrasound has also increased the clinician’s ability
When the physical examination fails to determine
the source of the pain causing the lameness, the diag- to identify pathology. CT has greatly improved the
ability to visualise the bones of the limb. MRI has
nosis of diseases of the horse’s foot requires, initially, vastly improved the clinician’s ability to visualise
localisation to the foot using regional and/or intrasy- soft-tissue structures within the foot and previously
novial analgesia. However, it is now known that local unidentified pathology within the bones, joints and
anaesthetic deposited in one synovial structure can soft tissues. The availability of these diagnostic tools
diffuse into an adjacent synovial structure or around in many countries is no longer a limiting factor in
an adjacent nerve, greatly decreasing the specificity of their use, although affordability is still problematic
pain localisation. An improvement in accuracy can be for many owners.
obtained by limiting the amount of anaesthetic used
and observing the response in relation to time. MANAGEMENT
Radiography of the foot is indicated whenever
the physical examination and diagnostic regional Treatment of diseases of the foot is in many ways
analgesia do not provide a diagnosis. In horses with similar to that of other parts of the limb, but its posi-
severe lameness, radiography should be performed tion at the distal end of the limb and the structure
before diagnostic analgesia in order to prevent exac- of the hoof capsule result in significant differences
erbation of a traumatic injury. The radiographic in treatment. Firstly, because the feet in working
examination varies depending on the results of the horses are usually shod, different shoeing techniques
physical examination, but typically either a series are used to achieve different ends: to protect the
of three radiographic projections (i.e. lateromedial, foot; to change the balance of the foot; to change
dorsopalmar and 45° dorsoproximal/palmarodis- the way the foot moves during the stride to prevent
tal oblique [upright pedal]) to examine the distal interference or enhance animation; to support the
phalanx is performed or a more extensive series to position of the foot on the ground; or to reduce the
examine the whole foot is performed that requires stress on an injured structure. Secondly, the struc-
an additional two projections (i.e. a 60° dorsoproxi- ture of the hoof capsule alters the approach that can
mal/palmarodistal oblique and a palmaroproximal/ be used to treat surgically deeper structures because
palmarodistal oblique [skyline]). Specific additional of the compromises to be made between exposure
oblique views may be performed as necessary. and stability of the hoof. Additionally, defects cre-
Scintigraphy is useful to detect disease that is ated in the integument of the foot cannot be sutured
occult on radiographs or to ascertain the significance in a comparable manner to skin.

DISEASES OF THE FEET

FOOT WOUNDS AND INFECTION partial-thickness skin wounds. Remnants of germi-
nal epithelium are distributed across the surface of
Foot wounds take many forms, from simple the wound, so healing is primarily by epithelialisa-
abscesses, to hoof wall avulsions, to punctures of tion. Defects that involve the full thickness of the
structures deep within the foot. Despite the varied coronary band, wall, sole or frog follow the four clas-
appearance and presentation of these wounds, there sical phases of wound healing. Following an injury,
are certain common features in the way they heal however, the hoof wall does not retract nor, in the
and are treated that warrant consideration in general repair phase, do the wound margins contract. The
terms to avoid repetition. epithelium that covers the wound may have diverse
Abrasions to the coronary band and iatro- characteristics depending on whether it originated
genic hoof wall avulsions heal in a similar way to from the coronary band, wall, sole, frog or pastern,