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Creep gate and pen

Creep feeding

CD-T vaccine
CD-T toxoid vaccine

Tools for vaccinating
Tools for vaccinating

Needles
Needles  

Sheep flock
Sheep flock

 Pregnant ewe
Pregnant ewe

 Lamb being born
Lamb being born

 
Drinking colostrum
Drinking colostrum

 
Content family
Ewe and lambs

Ram heads
Rambouillet rams  

Sheep on its knees
There are vaccines for foot rot



Soremouth
Soremouth

Giving soremouth vaccine
Administering the soremouth
vaccine to a goat

 

 


Flock vaccinations

Vaccinations are an important part of a flock health management program. They provide inexpensive "insurance" against diseases that can commonly affect sheep and lambs.

Clostridial Diseases

On most farms, the only universally-recommended vaccine for sheep and lambs is the CD-T toxoid. The CD-T toxid provides three-way protection against enterotoxemia caused by Clostridium perfringens types C and D and tetanus (lockjaw) caused by Clostridium tetani. There are 7 and 8-way clostridal vaccines that provide protection against additional clostridial diseases, such as blackleg and malignant edema, but the extra protection is often not necessary.

Type C
Enterotoxemia type C, also called hemorrhagic enteritis or "bloody scours," affects lambs mostly during their first few weeks of life, causing a bloody infection in the small intestine. Type C enterotoxemia is often related to indigestion and is predisposed by a change in feed, such as beginning creep feeding or a sudden increase in the milk supply, perhaps caused by the loss of a littermate. The only way to protect lambs from type C enterotoxmia is to vaccinate their dams during late pregnancy.

Type D
Enterotoxemia type D, also called "classic" overeating disease or "pulpy kidney disease," usually affects lambs over one month of age. Usually it is the largest, fastest growing lamb(s) in the flock that are affected. Type D overeating disease is usually precipitated by a sudden change in feed that causes the bacteria, already present in the lamb's gut, to proliferate, resulting in a toxic, usually fatal 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.

Passive immunity
To confer passive immunity to lambs through the colostrum (first milk), ewes should be vaccinated with the CD-T toxoid approximately 4 weeks prior to lambing. Ewes lambing for the first time should be vaccinated twice in late pregnancy, four weeks apart. Maternal antibodies will protect lambs for six to eight weeks so long as lambs consume adequate amounts of colostrum. It is recommended that a lamb consume colostrum in the amount of 10 percent of its body weight.

Lambs
Lambs should receive their first CD-T vaccination when they are approximately 6 to 8 weeks of age, followed by a booster 4 weeks later. If pastured animals are later brought into confinement or dry lot for concentrate feeding, a third vaccination should be given.

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 likely be more effective, as colostral antibodies usually interfere with vaccinations at very young ages. The lamb's immature immune system may also not be able to respond to vaccination at such a young age.

A better alternative may be to vaccinate offspring from non-vaccinated dams when they are approximately 4 weeks of age, followed by a booster 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.

Feeder lambs
Purchased feeder lambs should be vaccinated for type D enterotoxeia at the time of purchase and 2 to 4 weeks later. Feeder lambs purchased as 4-H or FFA projects should receive two type D vaccinations, if they were not vaccinated at the farm of origin.

Tetanus
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. An antitoxin provides immediate short-term immunity. If a tetanus toxoid product is administered at the time of docking or castrating, it will not provide adequate immunity, as toxoids take 10 days to 2 weeks to provide immunity and require a booster for complete immunity.

Rams and pet sheep should be boostered annually with the CD-T toxoid. As with ewes, they require two vaccinations the first time they are vaccinated.


Other diseases

In addition to clostridial diseases, there are other diseases for which producers may wish to vaccinate. The use of additional vaccines depends upon the health status of the flock, the perceived disease risk of the flock, and prevalance of diseases in the geographic area where the flock is located. In the U.S. (for sheep), there are approved vaccines for sore mouth, foot rot, caseous lymphadenitis, abortion, e. coli scours, parainfluenza-3 (PI-3), epididymitis, and rabies. Vaccines that are not approved for sheep are also sometimes used.

Soremouth
There is an approved vaccine for soremouth (contagious ecthyma, orf), a viral skin disease commonly affecting sheep and goats. The vaccine is live. It causes sore mouth infection (lesions) at a location (on the animal) and time of the producer’s choosing. Ewes should be vaccinated well in advance of lambing. Show animals should be vaccinated well in advance of the first show.

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 soremouth should probably not be vaccinated because the soremouth vaccine will introduce the virus to the flock/premises. Once soremouth vaccination is begun, it should be continued annually.

Footrot
Footrot is one of the most ubiquitous and economically devastating diseases in the sheep industry. It causes considerable economic loss due to the costs associated with treating it and the premature culling of carrier animals. There are two vaccines for footrot and foot scald in sheep: Footvax® 10 Strain and Volar™ Footrot Bacterin.

Neither vaccine 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. Footrot vaccines should be administered every 3 to 6 months, prior to anticipated outbreaks of hoof problems (i.e. prior to the wet/rainy season).

Abscesses (at the injection site) are not uncommon with the foot rot vaccines. The limitation of foot rot vaccines is that they might not include the strain of foot rot that is present in a particular flock.

Caseous lymphadenitis (CL)
There is a vaccine for caseous lymphadenitis in sheep. CL 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 CL 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, but it will not prevent the disease from occuring.


Abortion
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 infectious 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.

Epididymitis
Epididymitis is a major cause of reduced fertility in rams from western range states. There are vaccines for epididymitis (Brucella ovis), but none are deemed fully effective. In addition, vaccination interferes with the ability to eliminate infected rams from the flock, as vaccinated rams will test positive for B. ovis.

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 advised if the flock is located in a rabies-infected area, the animals are valuable, 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. The large animal rabies vaccine is approved for use in sheep. Producers should consult their veterinarian regarding rabies vaccination. Some states require rabies vaccination for exhibition at fairs and shows. All dogs and cats on the farm should be vaccinated against rabies.

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). Occasionally, 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 vaccinations 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.

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.


Future vaccines
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 to develop vaccines to protect small ruminants against Haemonchus contortus and other gastro-intestinal and blood-sucking parasites. The research is promising. Thus far, the challenge has been developing effective vaccines using recombinant DNA technology, as other methods of vaccine generation are not economically feasible.


Not vaccinating

Many sheep producers will tell you that they never vaccinate. Other producers vaccinate for diseases which are not a high risk. Vaccination is a form of risk management. Each producer must weights the pros and cons of vaccinating for a specific disease. If the cost of vaccination excees the expected losses, then vaccination is probably not cost-effective. Conversely, if expected losses exceed the cost of vaccination, they vaccination is a good risk management tool.

At the same time, it is not advisable to wait until you have a disease outbreak before instituting a vaccination program. The risk of a diseaes outbreak should be the criteria that is used to determine the need for vaccination. A producer's tolerence for risk will also come into play.


<== SHEEP 201 INDEX


Late updated 18-Sep-2013 by Susan Schoenian.
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