The use of vaccines is based on the principle that the animal possesses the ability to build up protective antibodies and cellular immunity against disease-causing organisms, notes the Ruminant Veterinary Association of South Africa (RuVASA).
A vaccine contains a dead disease-causing organism, or one that has been weakened. This organism is altered in such a way (artificially, genetically or naturally) that it no longer causes the disease in the animal, but still has the ability to stimulate the animal’s immunity so as to protect it against that disease.
It takes 14 to 21 days for antibodies to develop after vaccination. Animals immunised for the first time with, for example, an inactive vaccine against blackquarter, must be given a booster – that is, immunised again with the same vaccine three weeks after the first vaccination to ensure the development of immunity.
After the booster vaccination, the number of antibodies increases dramatically only 24 to 36 hours later, due to the presence of cells in the bloodstream that can ‘recall’ previous exposure.
Carefully read the directions for usage, obeying warnings to the letter. For example, if pregnant cows are immunised against brucellosis (strain 19 vaccine), they may abort.
Sterilise syringes and needles by boiling them in water for at least 15 minutes. Do not use disinfectants or methylated spirits. Use a separate needle for each animal as far as possible. Should a number of animals be injected with one needle, disease-causing germs can be transferred from sick to healthy animals.
Shake the vaccine bottle each time before filling the syringe. If the vaccine has to be mixed by adding freeze-dried material (in the form of a pill) to water, it should be injected immediately after preparation. It cannot be stored and used again after a day or two. (Lumpy skin disease vaccine is an example of this type of vaccine.)
Avoid exposing the vaccine to high temperatures and direct sunlight in storage or when vaccinating. These could destroy the active agents in the vaccine.
Different vaccines, such as those for lumpy skin disease and blackquarter, must not be mixed in the same syringe. Vaccines must also not be mixed in a syringe with other preparations such as antibiotics. When more than one vaccine is given at the same time, they should not be administered relatively close to each other on the animal, but preferably on opposite sides of the neck.
Note that vaccination of animals during a disease outbreak will not immediately stem the spread of the disease, as it takes two to three weeks before immunity develops. Should an animal be immunised during the incubation period of the disease, it will still develop the disease.
During disease outbreaks, it is especially important that every animal be immunised with a separate sterile needle. Do not vaccinate calves or lambs of immunised mothers before the age of 10 weeks. The colostrum-derived immunity will protect the calf or lamb, except where the product information indicates otherwise.
Finally, sit down with your vet and draw up an animal health management programme for your farm, taking into account any diseases that have been reported. This programme should be updated regularly as new risks are identified.
Source: Ruminant Veterinary Association of South Africa (RuVASA), a group of the SA Veterinary Association.