(e) Fracture of the Navicular Bone.—­Penetration of the substance of the navicular bone, without its fracture, adds nothing to the symptoms we have described under puncture of the bursa.  That the bone has been reached by the penetrating object may be detected by probing.  This, however, must be performed with care, especially if a flow of synovia is absent.  Otherwise, the wound, as yet, perhaps, superficial enough to avoid penetrating even the bursa, is made a penetrating one by the probe itself.

Fracture of the navicular bone is fortunately rare.

(f) Penetration of the Pedal Articulation and Arthritis.—­This we shall consider in greater detail in Chapter XII.  It is sufficient here to state that the condition may be suspected when a hot and painful swelling of the whole coronet makes its appearance.  There is at the same time a diffused oedema of the fetlock and the region of the cannon, sometimes extending upwards to the whole of the limb.

Of all the complications to be met with in punctured foot this is the one most to be dreaded.  The intense pain and the high fever render the animal weak and thin in the extreme.  The appetite becomes impaired, sometimes altogether lost, and the patient in many cases appears to die from sheer exhaustion.  Added to this is always the extreme probability of the wound becoming purulent, and later the dread of general septic infection of the blood-stream ensuing, and death resulting from that.  Even with the happier ending of resolution, anchylosis of the joint and incurable lameness is more often than not left behind. (See Suppurative or Purulent Arthritis, Chapter XII.)

(g) Ostitis and Caries of the Os Pedis.—­Injuries to the os pedis are met with in the anterior zone of the foot.  Evidence that the bone has been injured is not usually forthcoming until after the lapse of some days.  One is led to suspect it by the fact that there is no indication of the suppurative process extending further upwards, coupled with the facts that great pain, high fever, and extreme lameness persist, and that there is a continuous discharge from the wound of a copious blood-stained and foetid pus.  Used now, the probe reveals the fact that the bone is bared, and conveys to the hand that is holding it a sensation of crumbling fragility.

(h) Wounding of the Lateral Cartilage and Quittor.—­This occurs as the result of a deep stab in the posterior zone.  Ordinarily, wounds in this position are unattended with serious consequences, and the prick has to be a deep and a severe one before the cartilage is reached.  What then happens is that a spot of necrosis is formed round the seat of puncture in the cartilage.  This, unless met with surgical interference, is sufficient to maintain the wound in a septic condition; it takes on a fistulous character, and a quittor is formed. (See Chapter X.)