by
Susan Schoenian
Date of last revision:
12-Aug-2006 9:19
Vaccinations
are an integral part of a flock health management program. They provide cheap
insurance against many diseases that commonly affect sheep and lambs.
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The
best protection against colostridial diseases is to vaccinate pregnant
ewes prior to lambing.
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Clostridial
Diseases
Probably,
the only universally recommended vaccine for sheep is CD-T. CD-T toxoid provides
three-way protection against enterotoxemia caused by Clostridium perfringins
types C and D and tetanus (lockjaw) caused by Clostridium tetani. Seven
and 8-way combination vaccines that include additional clostridial diseases
such as blackleg and malignant edema are available, but generally not necessary
for sheep.
Enterotoxemia
type C, also called hemorrhagic enteritis or "bloody scours," mostly
affects lambs during their first few weeks of life, causing a bloody infection
in the small intestine. It is often related to indigestion and is predisposed
by a change in feed, such as beginning creep feeding or a sudden increase in
milk supply, perhaps caused by the loss of a littermate. Enterotoxemia type
D, also called overeating disease or "pulpy kidney disease," usually
affects lambs over one month of age, usually the largest, fastest growing lamb(s)
in the flock. It is precipitated by a sudden change in feed that causes the
bacteria, already present in the lamb's gut, to proliferate, resulting in a
toxic reaction. Type D is most commonly observed in lambs that are consuming
high concentrate diets, but can also occur in lambs nursing heavy milking dams.
To confer passive immunity to lambs through the colostrum, ewes should be vaccinated
for CD-T 2 to 4 weeks prior to lambing. Ewes lambing for the first time should
be vaccinated twice in late pregnancy, about four weeks apart. Maternal antibodies
will protect lambs for about two months, if lambs have consumed adequate amounts
of colostrum. Lambs should receive their first CD-T vaccination when they are
approximately 6 to 8 weeks old, followed by a booster shot 2 to 4 weeks later.
If pastured animals are later placed in a feed lot for concentrate feeding,
producers should consider re-vaccinating them for enterotoxemia type D. Purchased
feeder lambs should be vaccinated against type D at the time of purchase and
2 to 4 weeks later. Feeder lambs purchased as 4-H projects should receive two
type D vaccinations, if they were not vaccinated at the farm of origin.
Lambs whose dams were not vaccinated for C and D can be vaccinated with some success at two to three days of age and again in two weeks. However, later vaccinations will be more successful since colostral antibodies interfere with vaccinations at very young ages. A better alternative may be to vaccinate offspring from non-vaccinated dams at 1 to 3 weeks, with a booster 3 to 4 weeks later. Anti-toxins can provide immediate short-term immunity if dams were not vaccinated or in the event of disease outbreak or vaccine failure. Lambs whose dams were not vaccinated for tetanus should be given the tetanus anti-toxin at the time of docking and castrating, especially if elastrator bands are used. Rams and pet wethers should be boostered annually with CD-T.
In addition to CD-T, there are other vaccines that producers may include in the flock vaccination program, depending upon the health status of their flock and the diseases prevalent in their area. These include sore mouth, foot rot, caseous lymphadenitis, abortion, e. coli scours, parainfluenza-3 (PI-3), epididymitis, and rabies.
Sore
mouth
There is a vaccine for sore mouth (contagious
ecthyma, orf), a viral skin disease commonly affecting sheep and lambs. It is
a live vaccine that causes sore mouth lesions at a location (on the animal)
and time of the producer’s choosing. Ewes should be vaccinated well in
advance of lambing. To use the vaccine, a woolless area on the animal is scarified,
and the re-hydrated vaccine is applied to the spot with a brush or similar applicator.
Ewes can be vaccinated inside the ear or under the tail. Lambs can be vaccinated
inside the thigh. Because the sore mouth vaccine is a live vaccine and sore
mouth is highly contagious to humans, care must be taken when applying the vaccine.
Gloves should be worn. Flocks which are free from sore mouth should probably
not be vaccinated because the vaccine will introduce the virus to the flock/premises.
Once soremouth vaccination is begun, it should be continued yearly.
Foot
rot
Foot rot (and
foot scald) is one of the most ubiquitous diseases in the sheep industry.
It causes considerable economic loss due to the costs associated with treating
it and the premature culling of affected animals. There are two vaccines for
foot rot and foot scald in sheep: Footvax®
10 Strain and Volar™
Footrot Bacterin. Neither product prevents the diseases from occurring,
but when used in conjunction with other management practices such as selection/culling,
regular foot trimming, foot soaking/bathing, etc., vaccinations can help reduce
infection levels. Foot rot vaccines should be administered every 3 to 6 months
and especially prior to anticipated outbreaks of hoof problems (i.e. prior to
the wet/rainy season).
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When
using anti-abortion vaccines, ewes should be vaccinated two weeks prior
to breeding.
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Caseous
lymphadenitis (CLA)
There is a vaccine for caseous lymphadenitis
in sheep. CLA affects primarily the lymphatic system and results in the formation
of abscesses in the lymph nodes. It is highly contagious. When it affects the
internal organs, it evolves into a chronic wasting disease. The cost of CLA
to the sheep industry is probably grossly underestimated. The CLA vaccine is
convenient to use because it is combined with CD-T. Vaccination will reduce
the number of abscesses in the flock.
Abortions
Abortion
is when a female loses her offspring during pregnancy or gives birth to stillborn,
weak, or deformed lambs. There are vaccines (individual and combination) for
several of the causes of abortion in sheep: enzootic (EAE/Chlamydia sp.)
and vibriosis (Campylobacter fetus). Abortion vaccines should be administered
prior to breeding. Ewes being vaccinated for the first time should receive a
second vaccination (booster) in mid-pregnancy. Producers with problem flocks
may consider giving a booster as well.
Risk factors for abortion include an open flock and/or a history of abortions
in the flock. Unfortunately, there is no vaccine (available in the U.S.) for
toxoplasmosis, another common cause of abortion in sheep. Since the disease-causing
organism is carried by domestic cats, the best protection is to control the
farm's cat population by spaying/neutering and keeping cats from contaminating
feed sources.
E.Coli
Scours
Scours in baby lambs can be caused by E. coli. There is a vaccine
that can be administered to ewes at the same time as CD-T to pass immunity to
lambs through the colostrum. An alternative to vaccination is to give newborn
lambs oral E. coli antibody at birth.
Rabies
Though the risk to sheep is usually minimal, rabies vaccination may be considered
if the flock is located in a rabies-infected area and livestock have access
to wooded areas or areas frequented by raccoons, skunks, foxes, or other known
carriers of rabies. Frequent interaction with livestock may be another reason
to consider vaccinating. The cost of the rabies vaccine relative to the value
of the animals should be considered as well. The large animal rabies vaccine
is approved for use in sheep. All dogs and cats on the farm should be vaccinated
for rabies. Producers should consult their veterinarian regarding rabies vaccination.
Autogenous
vaccines
When no commercial vaccine is available, autogenous or custom vaccines can be
made. They are usually made from bacteria or viruses that have been isolated
on a farm in conjunction with a disease. Autogenous vaccines are usually not
as effective as commercial vaccines.
Giving
Vaccines
Most vaccines are given subcutaneously (sub-Q), i.e. under the skin. Some vaccines
are given intramuscularly (IM). Ocassionally, some are given topically (e.g.
sore mouth) or intranasally (e.g. Nasalgen®). For subcutaneous vaccines,
use a 1/2 or 3/4 inch, 18- or 20-gauge needle. Subcutaneous vacccinations can
be given over the ribs, behind the armpit, or high up on the neck. The needle
used to withdraw vaccine from the bottle should not be the same needle used
to inject the animal.
Click HERE for an article How to give injections (Daneke Club Lambs).
In order for vaccination programs to be successful, label directions should be carefully followed. Vaccines should be stored, handled, and administered properly. Only healthy sheep and lambs should be vaccinated. It is also important to note that vaccines have limitations and that the immunity imparted by vaccines can sometimes by inadequate or overwhelmed by disease challenge.
Click HERE
to view a table listing the Vaccines for Sheep.
Click HERE
to read The Use of Vaccines in Sheep (University of Minnesota)
C lick
HERE
to read Understanding Vaccination Programs: Timing is Everything (Michican
State University)
With the increasing role of small ruminants in small farms and sustainable farming systems, hopefully animal health companies will develop and license more vaccines for sheep. Scientists are currently working on vaccines to protect small ruminants against worms.
