Cases of this kind are not uncommon about some grading and lumbering camps and in contract work where, often, shelter for animals is given little thought; the result is a cruel waste of horseflesh.
Chronic articular rheumatism is occasionally observed in young animals that have never been in service. In these cases it seems that there exists an individual susceptibility and in some instances the condition is recurrent. Each attack is of longer duration, and eventually death results from continued suffering, emaciation and intoxication.
Acute bursitis and thecitis is of frequent occurrence in horses because of direct injury from contusion, punctures and other forms of traumatism. These synovial membranes, with few exceptions, when inflamed occasion a synovitis that may be very acute, yet there is less manifestation of pain than in arthritis.
It is only in structures such as the bursa intertubercularis or in the sheath of the deep digital flexor that an inflammation causes much pain and is apt to result in permanent lameness. This is due to the peculiar character of the function of such structures.
An acute inflammation of a small bursa may even result in the destruction of such synovial apparatus without serious inconvenience to the subject, either at the time of destruction or thereafter. Obliteration of the superficial bursa over the summit of the os calcis is not likely to cause serious inconvenience or distress to the subject unless it be due to an infected wound. Even then, with reasonably good care given the animal, recovery is almost certain. Complete return of function of the member and cessation of lameness takes place within a few weeks in the average case.
Where an infectious synovitis involves a structure such as the sheath of the tendon of the deep digital flexor (perforans) the condition is grave and because of the location of this theca the prognosis is not much more favorable than in an articular synovitis.
Inflammation of bursae and thecae may be classified on a chronological basis with propriety because the duration of such affections, in many cases, materially modifies the result. A chronic inflammatory involvement of a theca through which an important tendon plays may cause adhesions to form. Or there may occur erosions of the parts with eventual hypertrophy and loss of function, partial or complete.
However, in general practice a classification on an etiological basis is probably more practical and we shall consider inflammation of bursae and thecae as infectious and noninfectious.
Infectious bursitis and thecitis is usually the result of direct introduction of septic material into the synovial structure by means of injuries. Infection by contiguous extension occurs and also metastatic involvement is met with occasionally.