(d) Periostitis and Ostitis.

CHAPTER XI DISEASES OF THE BONES A. PERIOSTITIS AND OSTITIS.

We head this section, Periostitis and Ostitis, for the reason that in actual practice it is rare for one of these affections to occur without the other.

Should the periostitis be complicated by the formation of pus, then the vessels entering and supplying the bone are, in the suppurative area, destroyed.

This we shall consider under (a) Simple Acute Periostitis, (b) Suppurative Periostitis, (c) Osteoplastic Periostitis.

(a) Simple Acute Periostitis.

This is the periostitis that follows on the infliction of a slight injury to the membranean injury without an actual wound and free from infective material.

It may be, too, that in a case of 'nail-bound' a great deal of the pain and lameness is due to a simple periostitis caused by pressure of the bulged inner-layer of horn upon the sensitive structures.

Simple acute periostitis may and often does end in resolution.

(b) Suppurative Periostitis.

In ordinary cases of suppurative periostitis the pus formed is yellow in colour, creamy thick, and free from pronounced odourthe so-called 'laudable' pus of the older writers.

A further instance of infective periostitis is that met with in acute laminitis.

In this form of periostitis the membrane is again swollen and more vascular than in health, and is also easily separable from the bone.

The results of an osteoplastic periostitis are frequently met with in the bones of the foot, and are described by veterinary writers under such headings as 'Pedal Exostoses,' 'Ossifying Ostitis,' and 'Pedal Ossification' (see Figs.

In simple cases of periostitis, those caused by a blow but free from an actual wound, the most beneficial treatment is the continued application of cold by means of a hose-pipe or by swabs.

150.EFFECTS OF PERIOSTITIS ON THE PEDAL AND NAVICULAR BONES.

151.EFFECTS OF PERIOSTITIS ON THE PEDAL AND NAVICULAR BONES.

152.EFFECTS OF PERIOSTITIS

153.EFFECTS OF PERIOSTITIS ON THE OS PEDIS.

154, 155EFFECTS OF PERIOSTITIS

A condition of periostitis and ostitis in the region of the pyramidal process of the os pedis, usually preceded, but sometimes followed, by fracture of the process, and characterized by deformity of the hoof and an alteration in the normal angle of the joint.

The periostitis thus set up invariably takes the osteoplastic form, and as a result of this we have growths of new bone in the near neighbourhood of the joint.

It is in the later stages of the diseasethat is, when the pus has been evacuated and reparative changes commencedthat this osteoplastic periostitis is most marked, and it plays a large part in bringing about the condition of anchylosis, which we shall afterwards describe.

We get, therefore, in many cases, a condition of rarefactive ostitis occurring side by side with a slowly progressive caries within the bone, while outside is occurring an osteoplastic periostitis.

That an osteoplastic periostitis has been in existence is witnessed by the appearance along the edges of the bone of numerous outgrowths of bone, termed osteophytes (see Fig. 163).