What is Lockjaw (Tetanus) in Horses and should you vaccinate against it?

One of the most worrying elements of the current vaccination statistics UK wide issued by the Animal Health Trust is that if only 40% of Britain’s equine population has flu coverage then presumably only 40% or probably even less is also being inoculated against Lockjaw. This is just as worrying as the current flu outbreak, potentially more so.

The disease Lockjaw or to give it its proper title, Tetanus, is covered in the vaccination programme biennially so it is added to the flu inoculation every other year and described as anti-tetanus or anti-tet. If people are not vaccinating against flu then you are unlikely to be vaccinating against Lockjaw and this is a real worry.

What is Lockjaw?

Lockjaw takes its name from the disease’s attack on the central nervous system which causes the horse’s voluntary muscles to lock. At some point during the progression of the disease, the horse’s jaw will lock shut and this usually results in death or euthanasia as the horse is no longer able to eat or drink. The proper name for Lockjaw is Tetanus and the vaccination is therefore called, Anti-Tetanus. Humans also receive anti-tetanus injections throughout their life as we can all contract this disease from dirt entering a wound.

What causes Lockjaw?

Lockjaw is caused by toxins from the bacterium, Clostridium Tetani, which is found routinely in soil, manure and dust. Knowing how easy it is for horses to cut themselves in the field, it is a wonder that people do not vaccinate against this distressing and usually fatal disease.

Bacteria enter the body via a wound – it does not have to be significant in size or depth. They travel eventually to the brain via the bloodstream. Lockjaw is a serious and frequently fatal disease which is very distressing for the horse and those who care for him.

What are the signs and symptoms of Tetanus or Lockjaw?

Even in vaccinated horses, it can be easy to miss a tiny wound or cut, particularly in horses wintering out with thick, heavy coats. The signs of Tetanus may include some or all of the following:-

• A worried or distressed look on the horse’s face, the horse may have permanently flared nostrils or retraction of the eyelid caused by the muscle spasm
• An inability to open the mouth to eat or drink or difficulty in doing this with a slow or reduced range if the disease is still in its early stages
• The top of the tail sticks out
• Even if the horse can still eat, he may ‘quid’ which means dropping partially chewed food from his mouth or he may drool as he finds it harder to swallow. He may also retain food in his mouth for longer periods unable to either chew or swallow
• The horse’s ears may be in a permanently rigid position as if he is looking at something
• He may become oversensitive to sounds or touch
• He begins to move stiffly when there is no other reason for such an obvious and sudden change in his gait
• The third eyelid may prolapse and extend over half the eye
• Colic

More about Clostridium Tetani

This bacterium is commonly found in soil and has a fabulous survival mechanism. It is hugely resistant to heat and drying and can remain viable for years in the ground. The bacteria are also very resistant to chemical destruction.

The organism was first identified by the scientific community in 1884. It is especially present in the soil on farms as it is a very common organism in cattle and horse manure. It is most commonly introduced via a deep puncture wound but not always. The organism is anaerobic so can survive without the presence of oxygen. It will work its way from the point of entry through the bloodstream to the spinal cord – hence the telltale signs of stiffness and reduced movement - before heading to the brain.

Treatment for Tetanus

This usually depends on how severe the disease is and the rate of its progression which indicates the amount of toxin which has been produced in the horse’s body. Most nursing and veterinary care are therapeutic and lockjaw horses if they do live require a long period of very intensive nursing. Treatment may include some or all of the following:-

• If the point of entry of the bacteria can still be identified then this is cleaned and flushed with antibiotics. It is not always possible to find the entry site
• An antitoxin can be administered in early diagnosed cases but once the toxin is in the nervous system, the antitoxin will have no effect. It is helpful with any toxin that is still circulating in the bloodstream which is why it is so supportive in early diagnosed cases
• Sedatives and muscle relaxants are used to help with symptomatic relief
• Stable in a dark and quiet stall away from any other noise and the minimum of disturbance
• Blocking out noise with cotton wool in the horse’s ears can help
• Seriously compromised horses may need hydration and nutrition via intravenous fluid therapy and a nasogastric feeding tube

The mortality rate for tetanus is pretty high, somewhere between 50% and 75% of all cases will succumb, unfortunately. Even if a horse survives, it will require intensive nursing and treatment for a long period of time. Tetanus is seen most commonly in unvaccinated horses. If your horse is unvaccinated, a vet called to treat a wound will routinely inoculate for tetanus so incidences of the disease are seen less frequently than say the middle and later years of the 20th century. But not every small wound is spotted and tetanus bacteria can invade seemingly insignificant wounds and injuries which may be treated without veterinary attendance leaving a potentially serious risk in unvaccinated horses.

Flu vaccination appeared in the 70s and anti-tetanus alongside it which is what caused the decline in the disease. But lack of familiarity with a disease is what makes people complacent and this is why there is a lower uptake of the measles vaccine in children at the moment; many parents will never have seen a child ill with measles or remember suffering with it during their own childhood. The same is certainly true of lockjaw. Anyone witnessing a horse suffering from tetanus would never deny their horse the anti-tetanus vaccination.