Agriculture Reference
In-Depth Information
A vaccine is available for this disease, but standard veterinary practice is
to vaccinate animals only if an actual outbreak has occurred. Animals that
are already displaying clinical symptoms are vaccinated with the rest of the
fl ock. The reason for not vaccinating before the disease has shown up is that
the current vaccine is a live vaccine, meaning that it could cause an outbreak
if given to a clean fl ock.
If ewes need to be vaccinated, it should be done well in advance of lambing
so they have strong immunity before their lambs begin nursing, or else their
lambs may cause sores to develop on udders and teats, thus seriously risking
permanent damage due to secondary bacterial mastitis.
The vaccine is typically given in a wool-free area of the body: ewes can be
vaccinated inside the ear or under the tail, whereas young lambs can be vac-
cinated inside the thigh.
Disorders Resulting from Bacteria
The good news about these bacterial diseases is that they aren't actually very
common. The bad news is that when they hit, they hit hard, often with high
mortality rates.
Blackleg
Caused by the bacterium known as
Clostridium chauvoei,
this disease is char-
acterized by swelling in the heavy muscles and some lameness. Initially, the
disease is accompanied by fever, but by the time the other symptoms become
evident, the fever may have broken and the animal's temperature may be
subnormal. Most often, the disease follows an injury, though occasionally it
seems to come out of nowhere.
Blackleg is often a fatal disease, but if caught early, treatment with antibi-
otics may be effective. In areas where
Clostridium
species are prevalent, vac-
cination is the best option.
Caseous lymphadenitis
Caused by the bacterium
Corynebacterium pseudotuberculosis,
this problem is
seen throughout North America. Once introduced into a fl ock, it seems to
affect most of the members. The bacteria are thought to enter the sheep's body
initially through a nick or a cut. Once in, the bacteria start to form an abscess
in which they live. These abscesses may be external in the areas where there
are lymph nodes, but they can also be internal. The external form often clears
