Clostridial diseases remain a serious threat to unvaccinated sheep; death occurs within hours of rapid bacterial multiplication and exotoxin production although lambs with tetanus can survive for several days. There are long-established vaccination protocols using toxoid vaccines which prevent all common clostridial diseases in sheep. Initially, two vaccinations are given four to six weeks apart followed by annual vaccination four to six weeks before the expected lambing date to ensure adequate accumulation of protective immunoglobulins in colostrum. Lambs are vaccinated from three to four month-old with the programme complete before weaning unless sold for slaughter before waning of maternal antibody at around four to five month-old. All cases of clostridial disease are fatal despite treatment except for a small percentage of cases of malignant oedema (bighead) and blackleg which receive veterinary treatment during the very early stages of disease.
The more common clostridial diseases are lamb dysentery, tetanus, pulpy kidney, black disease, blackleg, struck and braxy. Large losses can be experienced when sheep are not correctly vaccinated therefore it is surprising that a UK survey revealed that almost 20 per cent of sheep farmers did not vaccinate their sheep on a regular basis. Sporadic cases of clostridial disease may occur in the flock in those lambs which have received nil or inadequate specific antibody in colostrum due to various factors including individual ewe not correctly vaccinated, lack of colostrum accumulation in the ewe’s udder due to poor feeding/mastitis, large litter, or feeding colostrum supplements/bovine colostrum from unvaccinated donors.
Vaccination is frequently practiced for protection of animals against clostridial diseases. A wide variety of vaccines is available, singly or in combinations that consist of bacterins, toxoids, or mixtures of bacterins and toxoids. Single vaccination with most clostridial vaccines does not provide adequate levels of protection and must be followed by a booster dose within 3–6 weeks. Vaccination of young animals does not yield adequate protective immunity until they are at least 1–2 months old. Therefore, most vaccination strategies target the pregnant dam so that maximal immunity is transferred to the neonate via colostrum. Most commercial vaccines are inactivated and usually contain 2-, 4-, 7-, or 8-way combinations of clostridial organisms/toxoids. These should be optimally timed for provision of maximal protection at the most likely age of susceptibility.
Tetanus toxoid is commonly administered as a single vaccine in horses but is often administered in combination in sheep, goats, and cattle. In sheep and goats, a common combination is tetanus toxoid plus Clostridium perfringens types C and D. In cattle, a combination frequently administered in feedlots is a 4-way vaccine that consists of killed cultures of C chauvoei, C septicum, C novyi, and C sordellii to protect against blackleg and malignant edema. A more complex clostridial vaccine that contains C perfringens types C and D in addition to the components of the 4-way vaccine may be administered to protect cattle against enterotoxemias as well. The addition of C haemolyticum extends the protection to include bacillary hemoglobinuria. The clostridial vaccines often cause tissue reactions and swelling and should therefore be administered to cattle in the neck and by the subcutaneous rather than the intramuscular route.
Features of Clostridial Vaccine Sheep
Preventable infectious diseases can have a severe economic and welfare impact on a sheep flock. When the obvious visible symptoms appear, the infectious disease is established, losses are to be expected and treatment effectiveness is variable. Prevention is more cost effective and economically efficient when the sub-clinical and chronic losses are accounted for.
Clostridial diseases are caused by a group of bacteria that have the ability to form resistant spores. Spores can concentrate in areas of high sheep usage e.g. around yards, sheds and troughs. They are resistant to extremes in temperature and can survive in soil for many years. Disease occurs only when the spore is present in damaged body tissue which provides the right conditions for the bacteria to germinate and to produce toxins. The signs of disease are caused by the toxins produced by these bacteria, not the bacteria themselves.
Dosage and administration
A lamb can be vaccinated from two weeks of age, but will preferably receive passive immunity from its mother by suckling just after birth. The dam can be vaccinated to increase antibodies found in the colostrum (first milk). When passed onto the lamb can provide protection for up to 12 weeks. Once the lamb is older, this protection from its mother wanes and it is no longer protected. The first vaccine of the primary course can be given to the lamb at three months of age, followed by the second primary vaccine a month to six weeks later. Since the administration is a subcutaneous injection, farmers can use the Accurus treatment gun to safely and accurately administer vaccines. The Accurus gun can be used single-handedly to simplify the procedure. Covexin 10 dosing regimens are deliberately kept simple too.
Sheep require an annual boost of the vaccine for full protection from clostridial disease. The first booster is required on the anniversary of the second primary vaccine (given at four months of age). If the booster is not given, the vaccine will not provide any further protection. When a ewe is pregnant, they require a booster to protect their young via their colostrum. This should be given 2-8 weeks before the lambs are born. The booster is then required every year at this time. It is vital that farmers keep a note of the date a booster is due to ensure continued protection for the flock.
Prices of Clostridial Vaccine Sheep
$29.60 – $105.42