Because of faulty conformation, some animals are subject to inflammation of these sheaths, and all forms of strenuous work which taxes the tendons greatly is apt to result in synovitis.  Direct injury such as blows may be the cause of synovial distension of thecae and the affection is to be seen in all horses that have done much fast work on hard road surfaces or pavements.

The usual case as it occurs in practice is a non-infective synovitis, but where puncture wounds cause the trouble, an infectious inflammation obtains.

Symptomatology.—­No trouble is experienced in diagnosing distension of tendon sheaths, for the affection is very palpable.  During acute inflammatory stages of this affection, some lameness is present—­in infectious inflammation lameness is intense.  Local heat and pain upon manipulation are readily discernible in all acute cases.  And finally, where there is reason for doubt, an aseptic exploratory puncture of the wall of the fluctuating enlargement may be made with a suitable trocar, and the discharging synovia will be proof of the existence of synovial distension.

After the affection becomes subacute or chronic, no lameness or inconvenience is manifested, and the condition is undesirable only because of its being a blemish.

Treatment.—­Acute non-infectious synovial distension of tendon sheaths is treated by aspirating as much synovia as possible from the affected theca (this is, of course, done under strict asepsis) and by means of bandages, a uniform degree of pressure is kept over the parts for ten days or two weeks.  The patient is kept quiet and in the course of two weeks an active blistering agent is employed over the region affected.  Usually, at the end of a month’s time, complete recovery has taken place and the subject may be gradually returned to work.

When synovial distensions are of long standing, it is necessary to take special precautions to check excessive secretion of synovial fluid, and, also because of the atonic condition of the tissues affected, resolution is tardy.  In addition to aspirating synovia, the introduction of equal parts of alcohol and tincture of iodin into the theca is necessary.  The quantity of this combination injected, depends upon the size of the sheath affected and the amount of synovia retained at the time injection is made.  Experience is necessary to judge as to this part of the work, but one may consider that a quantity between three and ten cubic centimeters of equal parts of tincture of iodin and alcohol constitutes the proper amount to employ.  Where much synovia is contained within the sheath at the time of injection, there occurs great dilution of the agent injected and consequently less irritation results.

The object of such injections is to check synovial secretion, and this is sought by the local effect of iodin in contact with the secreting cells together with the reactionary swelling which occasions pressure.  An increase in the local blood supply also follows.  In all cases where it is possible to employ suitable bandages, this should be done.  The ordinary derby bandages serve well and if their use is continued for a sufficient length of time, good results follow.