Vaccines for Sheep

Make no mistake, vaccinations in sheep are an economically important tool. Unfortunately, it is difficult to create a one-size-fits-all protocol. Each flock in different regions of the country will have a different set of circumstances. The following vaccinations are a good place to start whether you are re-evaluating your current vaccine system or creating one from scratch.

My first recommendation for sheep vaccines is always the CD and T toxoid to protect your flock against enterotoxemia caused by Clostridium perfringens (Types C&D) and tetanus caused by Clostridium tetani. CD and T vaccines are some of the most effective vaccines in ruminants and considered instrumental. Prevention of enterotoxemia and tetanus begins with vaccinating pregnant ewes with a CD and T vaccine during the fourth month of pregnancy. The vaccine prompts the ewe to create her own circulating antibodies against Cl. perfringens and Cl. tetani; these antibodies are meant to wind up in the colostrum. The preformed immunity will then be transferred to the lambs as they ingest the colostrum during their first 12 to 24 hours of life.

Another targeted place for a tetanus vaccine is with your young stock. Vaccinate lambs at four weeks of age and then booster 30 days later (or according to the manufacturer’s label). Administer another booster dose at the time of weaning. Vaccinate the rest of adult flock annually.

While tetanus antitoxin (different from the toxoid described above) is not a traditional vaccine, it is important to have on board when castrating or tail docking high risk lambs with unknown vaccination status against tetanus. The antitoxin is produced with high concentrations of preformed antibodies to provide immediate protection. Traditionally, on high risk animals, I give the antitoxin and the CD and T toxoid vaccine at the same time. Our protocol is to give the toxoid on the left and the antitoxin on the right, and never mixing the two together. The antitoxin goes to work immediately, while the toxoid takes 10 to 14 days to ramp up the animal’s own long-term immunity. Consider giving antitoxin to laming ewes with unknown tetanus coverage as well; the simple act of lambing can lead to exposure of tetanus leaving poorly vaccinated, or unvaccinated ewes at risk.

Vaccines can be a helpful tool against diseases causing abortion, still birth and weak lambs. Campylobacteriosis (formerly Vibriosis) is caused by the bacteria Campylobacter fetus and Campylobacter jejuni. As one of the most common causes of abortions in sheep, susceptible animals are exposed through feces, infected fetuses and placenta, uterine fluids and vaginal discharge shed by carriers. Abortions are typically late term. Enzootic abortion of ewes (EAE), like the name, causes abortions as well, but it is also one of the causes of pinkeye, joint problems in lambs, infertility in rams, and strangely, pneumonia and diarrhea. EAE is also caused by a bacterium, Chlamydia psittaci, and is primarily spread through contact with infected fetuses, placenta or vaginal discharges.  Leptospirosis is not as common as campylobacteriosis or enzootic abortion, but it can be found in all sorts of wildlife from skunks, rats and opossums to sheep, cattle, dogs and humans. A spirochete that lives in the kidney is the culprit; urine carries the infectious organism all over the place. Contaminated drinking water is a common source of infection that can cause abortion, anemia and multi-organ failure. A racoon can urinate on a barn roof and contaminate the puddle underneath the downspout; even freshwater sources can be contaminated with urine. Seeing animals drinking out of puddles makes me cringe! Vaccinate ewes and ewe lambs for Campylobacter, Chlamydia and Leptospira 3 and 6 weeks prior to your breeding season. Booster annually according to labeled directions.

Parainfluenza is an upper respiratory virus that can lead to pneumonia in lambs. An intranasal vaccine is available that is labeled for cattle; you may have to use a product with IBR in the mix, even though it is not needed for sheep. Just as with the clostridial vaccines, it is important to target the parainfluenza antibodies to end up in the colostrum. Therefore, vaccinate your pregnant ewes 3 to 4 weeks prior to lambing along with the CD and T.

This sums up the basic vaccines to throw in your basket followed by the next group of vaccines to ponder. Selection of the next set of vaccines should be based on documentation of these diseases in your flock, regional disease prevalence, risk factors associated with bringing in new animals and financial risk versus benefit.

Caseous Lymphadenitis (CLA) is fairly widespread in the United States with both sheep and goats having the most prominent display of the clinical disease: enlarged lymph nodes. It is spread in the environment and contagious through draining, relapsing abscesses. There are really only two scenarios: manage CLA in your flock or try like heck to keep it out. A vaccination program for CLA may fit into either scenario. Flock management of CLA can include a vaccination program in conjunction with quarantine and testing of all new arrivals. Beware that the current vaccines can bang a positive for CLA and compromise your ability to determine the true disease status at a later date.  Document testing and vaccination well, to eliminate confusion on whether an animal is positive due to a live infection or because of their vaccine status. CLA is rarely contagious to humans.

Similar to CLA, Contagious Ecthyma (Orf) can be detrimental to production, unsightly, and unwanted in flocks. People working with infected sheep can pick up the highly contagious virus that causes scabby pus-filled lesions of the skin or mouth. If Orf is a problem or concern, vaccinate young ewes 6 weeks prior to breeding.

A rabies vaccination should be considered in endemic areas that have a higher risk of skunk, fox, or bat rabies. Always look at more than just the financial side when considering including the rabies vaccination in your protocols: if a down or sick sheep has rabies, you, your personnel and your family are at risk of being exposed to the deadly virus.

Bluetongue is still here in the US despite trying to eradicate it. It is a virus that causes oral ulcers and sores, nasal discharge, crusty nostrils, and lameness. Death losses can exceed 80%. Cattle are also susceptible to Bluetongue. Any animal exhibiting these signs should be tested by your veterinarian for early detection and swift shut down of the disease in your flock. The virus is spread by a biting midge or no-see-um. A vaccine is available when advised by your state veterinarian in endemic areas.

As with any vaccine, there can be break-through or failure that results in the animal getting the disease despite the vaccine. Always follow the directions on the vaccine. Healthy animals have the best chance of invoking an adequate immune response to a vaccine. Proper mixing, storage and delivery are paramount. Changing needles when bent, bloody or burred or every 5 to 10 animals may be your protocol, or a new sterile needle for each animal may be more appropriate for your flock. Involve your veterinarian as part of your health care team. Be a good steward to your small ruminant flocks and prevent unwanted diseases through a sound management program that includes vaccinations.  

About the Author
Dr. Colleen Lewis is a 1996 graduate of Kansas State University, College of Veterinary Medicine. Her career has taken her to many places as a practice owner, consultant, embryologist, and mentor. She enjoys mixed animal practice, teaching, traveling, farming and high school sports with her husband, Andrew and their three boys.