Agriculture Reference
In-Depth Information
(OC), arthrosis or infectious conditions including arthritis and foot rot. Lameness is
associated with a variety of important risk factors such as: genetics, body conformation,
feed management, housing (especially floor condition) and/or exercise levels.
OC is regarded as a very common contributor to leg weakness and lameness in gilts and
young sows (Jorgensen, 2000). The lesions caused by OC can heal completely or progress
into an irreversible debilitating disorder, known as osteochondrosis dissecans (OCD)
or osteoarthrosis (OA) of joint areas in adolescent animals. OC/OA is a non-infectious
condition and is due to a failure in the endochondral ossification of the articular cartilage
and the growth plate. The progression of OC is characterized by dislodged segments
of epiphyseal and/or eroded articular cartilage resulting in exposure of mineralized
subchondral bone. In OA the joint surfaces become hardened (sclerosis). The major
difference between OCD and OA involves mineralization of tissues surrounding the joint
and excessive mineralization of bone in the case of OA. In some cases the cartilage may
re-attach and heal to form a wrinkled articular surface. The synovial membranes become
calcified and surrounding tissues are invaded by calcified outgrowths (osteophytes).
Various studies have indicated a multifactorial etiology where various environmental and
genetic factors are involved in the development of these lesions. OC tends to relate to
rapid weight gain which imposes pressure on the joints. Trauma is also one of the most
widely proposed aetiologies, however, its role is likely as a final insult to compromised
epiphyseal cartilage rather than as an initiating factor in the development of early lesions.
Slippery floors and lack of exercise are also considered contributing factors.
Specific clinical signs associated with these structural bone conditions are buck-kneed
forelegs, turned-out fore and hind legs, upright pasterns, stiff locomotion, and a tendency
to slip. The ambulatory difficulties can range from a shortened stride to a non-weight
bearing lameness, or from stiffness in the limbs to an inability or unwillingness to stand.
However, shifting lameness is common because multiple joints are usually affected.
Inflammatory arthritis is another condition that produces proliferation of joint tissue
with a thickening of the joint capsule and an increased accumulation of synovial fluids
that may contain blood or fibrin. Inflammatory arthritis can be caused by a variety of
pathogens including
E. rhusiopathiae
,
Streptococcus
sp.,
H. parasuis
and
Mycoplasma
hyosynoviae
. These conditions can be treated with antibiotics if caught early but it is
difficult to maintain minimum inhibitory concentrations of drugs in the joints and
prolonged treatment may be required for a successful outcome.
Osteoporosis is another common bone disorder in pigs, involving a loss or thinning of
mineralized bone tissue. Osteoporosis can cause lameness in swine, particularly in sows
at the end of the lactation period. The lack of mineralized bone tissue results in bone
fractures and is a major cause of culling in the breeding herd. Osteoporosis is mainly
caused by inadequate feed levels of minerals or an abnormal Ca:P ratio.
Hoof health is also a concern that relates to comfort, longevity and productivity. Hoof
lesions are common in pigs and can be an important underlying cause of lameness. It has
