Let’s talk about Tetanus again…
I previously posted this on our FB page, but it bears repeating.
Tetanus is caused by a nerve toxin that is produced by the bacteria Clostridium tetani. This bacteria can only thrive in necrotic (dead) tissue.
C.tetani is an anaerobe (it doesn’t survive in oxygen) which produces spores that are found in soil and manure. In general, the occurrence of C.tetani in the soil and, therefore, the incidence of tetanus in people, horses, and other species is higher in the warmer parts of the various continents.
Almost all mammals are susceptible to tetanus to some degree, with horses, lambs and goats being particularly sensitive to the bacteria, as are humans.
Dogs and cats are relatively more resistant than any other domestic animal. However the term relative is important to note, as we will discover.
When afflicted, animals with GENERALISED tetanus rarely survive without intensive veterinary care.
The C.tetani spores enter the body with soil, through wounds, particularly small, deep puncture wounds. In this environment the bacteria develop and multiply.
The spores of C tetani are unable to develop in normal tissue or even in open wounds. They require a degree of tissue death to have occurred in order to thrive. As the bacteria multiply, the neurotoxin is released and travels up the nerves.
The incubation period can vary, but is usually 10-14 days from exposure to the development of clinical signs. Sometimes the entry point cannot even be found, because it has healed by the time clinical signs develop.
When affected, dogs and cats can have a longer incubation period than other species, perhaps because of their higher level of innate resistance. But both localised and generalised cases can be seen.
A minor infection causes localised spasms only, perhaps of a limb. However any excess toxin can be spread through the body by the lymph system, leading to generalised clinical signs.
Once clinical, minor stimuli may causes spasm. These spasms range from mild to severe enough to break bones.
The author has seen localised tetanus in cats and dogs, and has seen generalised tetanus in horses, dogs and goats.
If left untreated, generalised tetanus is inevitably fatal, and is a truly horrible death, resulting in an inability to breathe.
Treatment of generalised tetanus in our small animals is incredibly labour and drug intensive and, these days, the best outcomes occur when the pet is treated at a critical care facility. The author has seen cases costing $15-$20,000
However Tetanus is easy and cost-effective to prevent in all species.
Most Humans are routinely vaccinated as babies and children, with adults requiring infrequent boosters. Long term protection is usually conferred.
Horses are routinely vaccinated also, ideally annually, as are farmed sheep and goats.
However our dogs, cats and hobby farm pets often go unvaccinated, and tetanus is not generally considered a core vaccine due to its rarity. This makes them potentially vulnerable.
It is believed that a common entry point causing clinical tetanus in dogs is the mouth in young pups. It is thought that the spores enter the wounds left by the teeth as they are lost, due to young dogs habits of picking and and eating things as part of their world exploration. The author has also seen cases linked to a nail bed infection and a migrating grass-seed. However most of the cases she has seen have been in young, teething dogs.
Dogs in rural and semi-rural environments may be at more risk than dogs in urban environments, due to the increased level of sporular contamination in the earth. Dogs that can access manure (sheep, cow etc) from bags of gardening manure could also be vulnerable.
The author recommends that owners of dogs in these environments consider including tetanus prevention as part of their routine vaccinations.
Two vaccinations with tetanus toxoid in puppyhood (the author recommends 8 and 12 weeks, or 12 and 14 weeks should, in theory, be adequate to confer lifelong protection, although the studies have not been performed to her knowledge. Teething doesn’t usually start until about 16 weeks of age, but chewing behaviours in this age bracket can cause oral wounds regardless.
For farm pets such as goats, sheep and alpacas the five-in-one vaccinations are very helpful, and should be done annually.
If you have pets on a farm or hobby farm, please consider talking to us, or your own vet, about their risk factors and about potentially protecting them against tetanus.
At Serpentine Vet we now ACTIVELY recommend two tetanus vaccinations in puppies as part of their original vaccination course.
These are not considered CORE vaccinations, but if your puppy is enrolled in our Free Vaccinations for Life Program, they will be administered at a reduced rate.