The work began with an abattoir survey whose aim was to identify
the major causes of loss due to arthritis.
The osteo-arthritic condition found most often was a bilateral
cubital osteo-arthritis seen in older sheep. Some of these jqints
were examined in more detail and a hypothesis put forward to explain
the development of the lesions.
Erysipelothrix rhusiopathiae was the most common bacterial
infection, and the remainder of the work concerns this organism and
its disease in sheep. The first review of' the literature deals with
the natural history of the organism, particularly in relation to its
infection in sheep. The remainder of Section I deals with ovine
serotypes of E.rhusiopathiae, interpretation of antibody titres and
evidence that subclinical infection with E.rhusiopathiae can occur.
Finally, attention is drawn to the susceptibility of the bacteria to
diluents containing insufficient organic matter.
Section IT describes the experimental work carried out which
investigated the use of E.rhusiopathiae vaccine and antiserum in
sheep. The literature pertaining to the use of inactivated
i vaccines is reviewed.
An experiment was carried out which failed to demonstrate that
that lambs could be protected against polyarthritis by the
prophylactic use of antiserum or maternal vaccination. ' In subsequent
experiments some of the possible reasons for this apparent failure
were studied. It was found that the criteria which had been adopted
as indicators of immunity, that is, rise in antibody titre and
resistance to intravenous challenge, were unsuitable, but that active
and passive immunity against E.rhusiopathiae could be shown when
animals were challenged by intradermal injection of live organisms.
Finally, the findings of the whole work are discussed with
particular reference to the epidemiology of E.rhusiopathiae infection
in sheep, and various hypotheses are put forward which explain the