Tetanus, also known as lockjaw, is caused by Clostridium tetani. Usually tetanus is seen in lambs (less than six months of age) in the spring following castration and/or docking. Clostridium tetani are gram positive, anaerobic, rod-shaped bacteria that are found in the soil. Bacteria gain access through wounds
from foot punctures, needle perforations, shearing, and tagging. Clostridium tetani releases two different
toxins; tetanolysin, which hemolyzes erythrocytes and tetanospasmin, which attacks the nervous tissue.
The majority of the clinical effects of tetani are due to the neurological effects of tetanospasmin.
Tetanospasmin diffuses in the muscle and neuronal terminals, traveling up the motor axons to the central
nervous system. At the spinal cord and medulla, synaptic inhibitions are decreased, resulting in muscles
that are continuously contracted until physical exhaustion occurs and then death.
Clinical signs typically occur four to ten days post injury.
As the disease progresses
The mortality rate is 100% and affected sheep die within three to ten days.
History of injury within the last 30 days muscles are stimulated by auditory and physical stimuli.
Primary differentials include strychnine poisoning (which usually lasts for only a few hours) and hypomagnesaemia (chemical analysis of blood will include low magnesium).
Using clean needles and clean tools for castration, tagging, shearing and docking, can prevent tetanus. A vaccination program that includes an eight in one clostridium vaccine can protect against clostridial disease. Suggested vaccination program for ewes and rams give initial vaccination then schedule a secondary vaccination six weeks post-initial vaccination give booster two to four weeks before lambing for lambs to be kept over 16 weeks (for fattening or breeding)
(If lambs are out of unvaccinated or inadequately vaccinated ewes, they should be either vaccinated
during the first week and given a secondary vaccine at six weeks or be given 100 ml of colostrums from a vaccinated ewe.) Treatment of animals that have puncture wounds should have an injection of tetanus antitoxin and antibiotics. The wound should be thoroughly cleaned with water and antibacterial solution. Smaller puncture wounds should be opened and flushed with hydrogen peroxide solution. Animals affected with tetanus should be placed in a dark and quiet area, and be given chlorpromazine daily (total of 100 mg divided up in several doses given over several days.
Sheep Production Handbook, Oct. 1988. Sheep Industry Development Program, INC. Pg 7-8.
Ricketts, G.E., Scoggins, R.D., Thomas, D.L. Management Guidelines for Efficient Sheep Production.
1993. Pg. 24-25.
Here are some links for more information
Colorado State College of Veterinary Medicine & Biomedical Sciences
Pipestone Veterinary Supply