Tetanus in dogs
Tetanus is – fortunately! – an uncommon problem in dogs.
The bacteria which causes tetanus (clostridium tetani) can lie dormant in the soil for many years. It usually enters the body through an open wound, especially one contaminated with soil.
Once the bacteria are established it starts producing a toxin which affects the local nerves, spreading up the nerve fibres and eventually reaching the brain. The toxin causes the nerves to tell muscle fibres to contract – to go into tetany – so the first signs are muscle tension and stiffness in the affected area. For example if a wound on a toe becomes infected, the early signs may be a stiff stilted gait in that limb. As the toxin spreads further stiffness can develop in all four limbs (sawhorse stance) and cause a stiff elevated tail. Contraction of the facial muscles results in elevated ears, sunken eyes, third eyelids protruding and sometimes a sardonic grin as the lips are pulled back.
The early signs may be subtle and easily missed. Death can result through contraction of the diaphragm and heart muscle. If the signs are only slowly progressive then the prognosis is much better, though the effects of the toxin can last up to six weeks.
Treatment involves high doses of antibiotics and tetanus anti-toxin. Severely affected dogs may also need IV fluids and nutritional support as they may not be able to open their mouths through the muscle contraction (hence the colloquial name ‘lockjaw’). There is no vaccine available for dogs simply because it is such an uncommon disease. Cats may also be affected by tetanus but it is rarely seen as they are much more resistant.
The picture shows a dog with early tetanus – note the ears pulled right up.