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Vaccinating with CDT

By Kelvin Moore, Sade Payne, Elizabeth Spahr, Ohio State University Animal Science Undergraduate Students, and Brady Campbell, Program Coordinator, Ohio State University Sheep Team

With lambing season right around the corner, shepherds need to start preparing now. The CDT vaccine is yet another management tool found in the shepherd’s toolbox that is used to protect small ruminants against clostridium perfringens types C and D as well as clostridium tetani (tetanus). Appropriate use of this vaccine is a safe, cheap, and an effective method used to control for clostridial diseases in your flock.

Commonly referred to in the industry as the ‘overeating disease,’ clostridium perfringens types C and D are associated with feedstuffs and can lead to enterotoxemia. The bacteria that cause enterotoxemia are present in all animals, just at low population levels. Issues arise when these bacterial populations experience a rapid period of growth and proliferation due to an increase in actual bacterial numbers or due to a rapid change in the diet. As a result, the bacteria grow rapidly, toxins accumulate, and are then distributed throughout the body resulting in serious health issues or death.

For example, type C is commonly found around the farm living in the soil and manure pack. This is one reason why it is important to provide a clean lambing and nursing area. Lambs can contract this bacteria via direct contact with dirty surfaces or by nursing on dirty udders. Therefore, lambs that nurse excessively could be at higher risk as they are in frequent contact with a dirty udder. Animals with a type C infection may show signs of severe diahrrhea.

One the other hand, type D is more closely tied to overeating disease. This type of bacteria generally affects the the largest and fastest growing lambs. This is due to the large amounts of feed, specially grain, that these lambs are consuming. It should be noted that enterotoxemia can be an issue on rapidly growing lush pastures, but it tends to be more of an issue with lambs being fed high concentrate diets. In this case, due to a rapid increase of grain in the diet, type D bacteria use this as a fuel to reproduce rapidly. Unfortunately, lambs that experience a rapid spike in bacterial numbers due to a type D infection die quickly making it difficult to detect and treat these animals.

Not to forget the third piece of this puzzle, the CDT vaccine also helps protect against clostridium tetani or tetanus. This is another important bacterial species that we must take seriously. Basic production practices such as shearing, animal identification, tail docking, and castration can all result in an open wound which allows for for this bacteria to enter the animal’s body. Some classic signs that are associated with tetanus is lock jaw and overall stiffness of the body. Unfortunately, as seen with type D infections, once visual signs of the disease are present, death is inevitable.

So now that we have a better understanding of what these diseases are and what we can do to combat against them, the next step is to understand how to appropriately use this vaccine. This vaccine is given subcutaneously either in the neck, axilla (armpit), over the ribs, or in the flank. All lambs should receive a total of three doses of the vaccine. For lambs born from vaccinated mothers, lambs should be given booster shots at 4 to 8 weeks of age and then again at 4 weeks later. You will note that there is some variability in the time frame of booster shots. This time frame will be dependent upon your production practices as it is important to give boosters prior to tail docking and castration for added protection. On the other hand, for those lambs born from ewes that were not vaccinated, these lambs should receive their first vaccine during their first week of life followed by two boosters, each given in 4-week intervals.

For all other mature animals remaining on-farm, an annual booster is key. For ewes, it is easiest to administer the vaccine one month prior to lambing. This strategy allows producers to vaccinate more than one animal at a time, an efficient use of the vaccine. In the case of first time lambing ewes, two doses at six and three weeks prior to lambing is helpful as well. For the rams, yes they need a booster as well, administer the vaccine prior to breeding. Most producers use a marking harness or have to move the rams to a breeding area. During these activities it is easy to administer the vaccine as you are already handling the animal.

At the cost of only $0.32 per dose, it is hard to make an argument upon why you would not use this vaccine. Mortality rates have been reported as high as 40% for unvaccinated flocks and in the neighborhood of 0.5% for vaccinated flocks. With the current lamb market, spending around $1 per lamb to assure the health of your flock is certainly worth the investment in the long run. However, it should be noted that a vaccine should never be used simply as a band-aid to cover up an issue, rather it should be used to compliment sound management practices. Therefore, the combination of a sound vaccine program in addition to proper feeding, handling, and housing will be key to a successful lambing season. For more, visit this link: CDT Vaccine: When, How, and Why.

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