ARTHRITIS IN CATTLE
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temperature, hot swollen joints, anorexia, and suppressed ruminations, which
are typical of inflammatory arthritis, are not present in degenerative arthritis. In
many advanced cases of arthrosis, crepitus can be readily discerned when the
animal moves. Secondary muscular atrophy and malfunctioning joints become
evident as the disease becomes more severe. The clinical manifestations and the
course of the disease vary with the biological response of the individual animal.
Familiarity with the anatomy and aging processes of normal individuals of the
species is imperative in order to detect pathological changes (7). Inheritance
sometimes appears to be a factor which predisposes to degeneration. This theory
can be supported by pedigrees and records of certain, well documented cases.
Cattle with straight hind legs seem to be more susceptible to arthritis because
of the constant strain and injuries to the joints that result from improper support
of the body weight (8). On the other hand, many straight-legged cattle do not
develop this condition and, conversely, some of the seriously affected animals
are not straight-legged.
In older bulls degenerative joint changes often result in the inability to breed
(9). Impaired locomotion and activity due to affected joints has resulted in the
slaughter of many valuable bulls. Spastic contractions of the hind limbs have
been seen in young bulls and cows, but are most frequently observed in older
bulls. There is also a hereditary condition causing spastic paresis of the hind
limbs in calves. In most cases, however, these animals are removed from the
herd before they reach one year of age (5). A number of yearling bulls go
through a period of swollen hocks, but they tend to overcome this condition as
they mature. The age and management of the animal are associated with the
clinical manifestations of the disease. Large, heavy bulls, housed in small stalls
with concrete floors, have a high incidence of puffy hocks and experience great
difficulty in standing up. Animals raised in open box stalls with outdoor non-
concrete runs that provide ample room for proper exercise are not as likely to
develop the spastic arthritis-like syndrome and degenerative changes as early in
life as animals housed in small, inadequate stalls with concrete floors.
PATHOLOGICAL FINDINGS
Inflammatory arthritis may be serous, fibrinous, or purulent. Advanced cases
show proliferation of both the synovial membrane and the outer layer of articular
cartilage, combined in many cases with a proliferation of pericapsular connective
tissue. Thickening of the articular capsule and an increase in the amount of joint
fluid cause joint enlargement. The degree of erosion of the articular cartilage
varies with the age, the stage of inflammation, and mechanical factors.
The extent of the lesions associated with degenerative arthrosis is influenced
by many factors. We have listed before some of the terms used to describe such
degenerative joint diseases. Some of these are merely descriptive terms derived
from empirical findings, clinical signs, tissue changes, and X-ray observations. Age
certainly plays a role, as this disease occurs chiefly in older individuals. The
anatomical structure and basic function of specific joints influence the manifesta-
tion and incidence of lesions and symptoms; the larger, freely movable joints are
more severely and more frequently involved. Some correlation has been noticed
between the weight of the animal and the severity of the pathological changes.