Agriculture Reference
In-Depth Information
tect animals for a short time when disease is present in the herd and to treat
infected animals. Antisera can be used for young lambs.
On rare occasions, antiserum may be administered along with a vaccine to
give immediate protection while the animal's own active immunity is devel-
oping. Check with your veterinarian before administering antiserum and
vaccine together, because in some instances the hyperimmune serum can
neutralize the vaccine.
Bacterins
Bacterins are suspensions of bacteria that were grown in culture media and
then chemically or heat killed. These vaccines are not capable of producing
disease and can be used without danger of spreading disease. The bacteria
used in the production of the various bacterins are highly antigenic strains
isolated from animals that have succumbed to the particular disease.
Bacterins are often suggested as an aid in establishing immunity to spe-
cifi c diseases. Always follow the manufacturer's label. Most bacterins require
a priming injection, followed by a booster in 1 to 4 weeks. More often than
not, very little immunity is obtained after the priming injection — actual pro-
tection is obtained after the booster shot. Bacterins do not confer long-lasting
immunity. An animal is usually protected for a maximum of 6 months and
sometimes a year between boosters.
Toxoids
Solutions of inactivated toxins make a vaccine known as a toxoid, which is
derived from bacteria that bring about disease by producing toxins that enter
the bloodstream and cause severe tissue or nerve damage (such as tetanus,
enterotoxemia, and blackleg). Since it is the toxin produced by the bacte-
ria and not the bacteria themselves that cause disease, toxoids stimulate the
sheep to produce neutralizing antibodies against the toxin, thereby protecting
against their deadly effect.
Vaccines
A vaccine is a modifi ed live or killed biological preparation that, when admin-
istered to the animal, stimulates the immune system to build its own protec-
tive antibodies. Modifi ed live vaccines contain strains of the virus that cannot
cause the disease but still retain the immune-stimulating potential. With few
