A NOTE ON OSTEITIS DEFORMANS IN TWO FOWLS

                                            BY

                    R. VENKATARAMAN, G.M.V.C.,

         Laboratory Assistant, Madras Veterinary College.

        (Received for Publication on 7th December 1935.)

                                    FOREWORD

Several bony diseases affect poultry. These may be either neoplastic, in-
flammatory, or constitutional in their origin. Though pathological conditions
occur commonly in bones, yet very little is understood regarding their nature.
The technical difficulties associated with their histological examination are many
and the introduction of such terms as calcareous infiltration, calcification, ossifica-
tion, exostosis, osteitis, osteo-sclerosis, hyperostosis and the like merely convey
an idea of the nature of such changes.

Diseases occurring in bones go by different names depending upon their origin,
situation, and histological characters. When neoplastic in origin, they may grow
out as exostoses in the form of excrescenes from the outer surface of a bone or may
grow in and project into the medullary cavity. In some instances, the matrix
becomes dense resulting in ' compact or ivory osteoma'. The majority of the
osseous growths appear to be inflammatory in origin, as for example the formation
of a callus round a fracture. Sometimes, the infiltration of chronic inflammatory
foci with calcium salts may simulate bone formation and it must be remembered
that the nature of the majority of bone tumours may be very difficult to interpret.

Diseases of constitutional origin also affect the skeletal system in poultry.
These are all grouped under nutritional or vitamin deficiency diseases such as
asthenia (going light), gout, rickets, osteoporosis, osteomalacia and osteitis de-
formans. Osteitis deformans is the name applied to the morbid process which
usually affects the entire skeleton in adult life. It is a chronic constitutional
disease characterised by the deposition of a fibro-osteoid tissue in such an excess
as to enlarge and harden the affected bones. This kind of chronic osteitis is of a
formative type, in which there is new formation of bony tissue from the osteogenic
layer of the periosteum and sometimes also from the endo-osteum in the medullary
canal giving the bone an ivory like consistency ; the other kind is known as the
rarefying type in which there is absorption of bone, which is replaced by granula-
tion tissue, as in tuberculosis and actinomycosis of the jaw in cattle.

This note is intended to record briefly an unusual condition of the limbs seen
in two fowls. The cases are of further interest as they revealed spirochaetes in their
blood in addition.

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