Agriculture Reference
In-Depth Information
When disease does occur, the usual approach is to ensure rapid exposure to all animals,
especially the pregnant sows so that they will produce immunity within two or three
weeks and then be able to protect their litters via colostrum and milk. Vaccines for these
diseases tend to have poor efficacy and are not widely used unless the diseases become
endemic in the herd. Exposure of sows to feces containing live virus, to create disease
followed by immunity, followed by sanitation measures and careful pig movement can
eliminate these diseases from infected herds.
Sows in confinement rearing tend to not have a problem with intestinal parasites, although
routine deworming prior to farrowing to control the spread of round worms (
Ascaris
suum
) is usually recommended in all herds. Sows on pasture are prone to a variety of
parasites including red stomach worms (
Hyostrongylus rubidus
) and nodular worms
(
Oesophagostomum
sp.). Chronic parasitism of outdoor-reared sows can lead to weight
loss and unthriftiness and an anthelmintic program is recommended for these herds.
18.5.4
Skin/integument
External parasitic diseases such as mange (caused by mites,
Sarcoptes scabiei
) and
pediculosis (caused by lice,
H. suis
) were once major problems in sow herds but
these pathogens have been eliminated from most modern pig farms because of the
introduction of very effective treatments. There are highly efficacious acaricides that can
be administered in a strategic manner to eliminate these diseases from the herd. Both
lice and mange mites cause the sows to be restless and to engage in constant rubbing. The
presence of these conditions causes reduced lactation performance resulting in lighter
weaning weights and greater preweaning piglet mortality (Davies, 1995).
Lesions of the skin of sows are very obvious compared with other animal species because
of the lack of hair cover. Changes to the skin are often the first signs of disease that may
be systemic in nature. A diagnosis of erysipelas is often made on the basis of raised,
reddened, diamond-shaped skin lesions. A diagnosis of PRRS may be suspected on the
basis of congestion of the sow's ears (blue ear disease).
Wounds to the skin are generally readily visible and, partly because of this, the issue of
shoulder sores has gained attention from a welfare standpoint. Lactating sows spend a
great deal of time lying on their sides nursing and are prone to develop sores in the area
of the spine of the scapula. Sows that have been selected for leanness and for high milk
production tend to have very little protective padding. Slatted farrowing crate flooring
causes increased concentration of pressure to specific points on the sow's shoulder, and
thus increase the likelihood of sores developing. Thin sows and older sows are at greater
risk of shoulder sores. Attention to feeding during lactation to ensure adequate body
condition, and improved farrowing crate design, possibly with the use of pads, can reduce
the prevalence of skin wounds.
