Flock vaccinations


• Vaccinations are an integral part of a flock health management program. They provide inexpensive "insurance" against diseases that can commonly affect sheep and lambs.
  
  
• Clostridial Diseases
  In most cases, the only universally-recommended vaccine for sheep and lambs is CD-T. The CD-T (toxoid) vaccine 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 most sheep flocks.
  
  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 milk supply, perhaps caused by the loss of a littermate.
  

  Type D
  Enterotoxemia type D, also called 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 afflicted. 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 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 six to eight weeks, assuming lambs have consumed enough of colostrum.
  
  Lambs
  Lambs should receive their first CD-T vaccination when they are approximately 6 to 8 weeks of age, followed by a booster 2 to 4 weeks later. If pastured animals are later brought into confinement or dry lot for concentrate feeding, producers should consider re-vaccinating them for enterotoxemia type D.
  
  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 of age, followed by 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.
  
  Feeder lambs
  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 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 for these procedures. An antitoxin provides immediate short-term immunity.
  
  Rams and pet sheep should be boostered annually for CD-T.

• Other diseases
  In addition to CD-T, there are other vaccines that producers may wish to include in their 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.

• Soremouth
  There is a vaccine for soremouth (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. 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 vaccine will introduce the virus to the flock/premises. Once soremouth vaccination is begun, it should be continued yearly.

• 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 affected 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 and especially prior to anticipated outbreaks of hoof problems (i.e. prior to the wet/rainy season). Abscesses are not uncommon with the foot rot vaccines.

• 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.
  
  

• 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 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. The challenge is developing effective vaccines using recombinant DNA technology.
  
  
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Last updated 19-Jun-2009
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