s, when present, usually cause recurrent attacks of
lameness; myalgia, due to subsurface injury occasioned by contusion,
generally produces an ephemeral disturbance; and while these are
examples of cases where occult causes are active, they are by no means
unprecedented. In cases where the cause of lameness is not definitely
located, and when by the process of exclusion one is enabled to decide
that the seat of trouble is in the hip, a tentative diagnosis of hip
lameness is always appropriate.

In one instance a Shetland pony evinced a peculiar form of intermittent
lameness which affected the left hip, and repeated examinations did not
disclose the cause of the trouble. After about a year there was
established spontaneously an opening through the integument overlying
the region of the attachment of the psoas major (magnus), through which
pus discharged. With the occurrence of this fistula, lameness almost
entirely disappeared, but the emission of a small amount of pus
persisted for more than a year. The subject was not observed thereafter
and the outcome in this case is not a matter of record. Whether there
existed a psoic phlegmon due to metastatic infection or necrosis of a
part of a lumber or dorsal vertebra is a matter for speculation. Thus
the presence of some anomalous conditions which affect the pelvic region
and cause lameness may be discovered, yet both in hip and shoulder
regions causes may not be definitely located by means of practical
methods of examination.

Injuries of all kinds are the more frequent causes of hip lameness. In
such cases, lameness may result directly and resolution be prompt, or
the claudication become aggravated in time, due to muscular atrophy or
degenerative changes affecting the hip joint or nerves. Rheumatism or
metastatic infection may be the cause of hip lameness as well as
affections of the pelvic bones, lumbar and sacral vertebrae. Hip
lameness may also be provoked by melanotic or other tumors.

In the diagnosis of hip lameness, one is guided in a general way by the
character of the impediment manifested. Swinging-leg lameness is often
present and the impediment is more accentuated when the animal is caused
to step backward. In many cases lameness is mixed, being about equally
noticeable during weight bearing and while the member is being swung. By
exclusion of causes which might affect other parts; one may definitely
locate the cause of the trouble or determine that a certain