Synovia is a good culture medium and the environment is ideal for multiplication of bacteria; consequently, the grave disturbances which may attend the introduction of pathogenic organisms into a synovial cavity as the result of a puncture wound are not to be forgotten. The veterinarian is in no position to estimate the virulency of organisms so introduced; neither can he determine the exact degree of resistance possessed by the subject in any given case. Therefore, he is uncertain as to the best method of handling such cases where an injury has been recently inflicted and positive evidence of the existence of an infectious synovitis is not present. If one could determine in advance the degree of infection and injury that is to follow small penetrant wounds of joint capsules, it would then be possible to select certain cases and immediately drain away all synovia and fill the cavity by injection with suitable antiseptic solutions. This offers a broad field for experimentation which will in time be productive of a radical change in the manner of treating such cases. _Metastatic arthritis_ is seen more frequently in colts or young animals than in mature horses and we here take the liberty of classifying with the arthritis of omphalophlebitis and strangles the so-called rheumatic variety. A specific polyarthritis or synovitis which attends navel infection of foals is perhaps the most frequent form of arthritis that is to be considered metastatic. This condition is truly a disease of young animals and, while it is a specific arthritis, the cause is yet to be attributed to any definite pathogenic organism with certainty. This condition is well defined by Bollinger as quoted by Hoare,[1] when he calls it a purulent omphalophlebitis due to local infection of the umbilicus and umbilical vessels, by pyogenic organisms, causing a metastatic pyemia. This affection is grave; its course is comparatively brief; the prognosis is usually unfavorable; and omphalophlebitis occasions a form of lameness which at once impresses the practitioner that serious constitutional disturbance exists. Its consideration properly belongs to discussions on practice or obstetrics and diseases of the new born, and it has received careful attention and is discussed at length in these works. A second form of metastatic arthritis is met with in strangles. Strangles occurs in the young principally and is not a frequent cause of synovitis or arthritis in the adult animal. Strangles or distemper is, according to most pathologists, due to the Streptococcus equi. Hoare[2] states that in this type of specific arthritis the contagium is probably carried by the blood. He gives it as his opinion that even laminitis has occurred as a result of the streptococcus-equi. This, indeed, would point toward probable extension by the blood as well as by way of lymph vessels.