Tetanus is one of those conditions that very few of us have seen, because most Australians are vaccinated against it.
If you haven't and you step on a rusty nail, you're likely to get a booster before signs of tetanus can develop.
But this nasty condition also affects animals.
Tetanus is caused by a toxin produced by the bacteria Clostridium tetani.
This bacteria is found everywhere in soil and the intestines of animals, and thus it is commonly found in faeces and dust.
Once it finds itself in favourable conditions - say, for example, inside a deep wound where oxygen levels are low - it produces a toxin which affects the nervous system, causing tetanus.
In dogs, the most common causes of tetanus are deep, contaminated wounds in the paws.
They may be caused by sharp objects, foreign bodies like splinters, or bite wounds.
In puppies, it can be associated with wounds in the mouth that occur due to teething.
The inciting wounds can be so small that they heal over before the signs of tetanus develop, making it tricky to determine the site of entry.
The syndrome is characterised by excitement of nerves supplying the muscles, leading the muscles to become fixed in an extended position.
This leads to changes in the facial appearance of dogs.
They may appear to develop a smile, an expression known as risus sardonicus.
The skin above their eyes can become taut and the ears pulled into an erect position.
The limbs can become rigid, stiff and extended, and as the severity of the condition progresses, dogs may be unable to walk.
The condition is clearly uncomfortable and painful for affected animals.
Fortunately, it is also reasonably rare.
Tetanus is even less common in cats than it is in dogs.
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In cats it manifests a little bit differently.
Whereas dogs tend to experience the more generalised form of the disease, with all parts of the body involved, cats often have a localised form of the disease.
Thus a single limb may be rigid and extended.
In a recent study, almost 90 per cent of affected dogs that received care survived - but they required an average of eight days in hospital (Drfelt et al., 2023).
Treatment requires resolution of the originating infection and prevention of further toxin production, neutralisation of the toxin that has been produced, and supportive care until the effects of the toxin dissipate.
The latter can take a week or two.
Dogs usually require intensive care, including muscle relaxants, pain relief, nutritional and fluid support (they may not be able to eat and drink by themselves) and close monitoring, as tetanus can impact the heart and respiratory systems.
This can take a couple of weeks, and may be costly.
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Tetanus vaccination is not generally recommended for dogs and cats.
The mainstays of prevention are minimising faecal contamination of the environment by picking up after animals, prevention of penetrating wounds, and prompt cleaning of wounds when they do occur, to reduce the risk of infection.
Common antiseptics used in humans can be toxic to dogs and cats. Saline or dilute (10 per cent povidone-iodine, e.g. betadine) can be used to clean wounds on the skin.
Prompt veterinary attention should be sought for deep wounds.
- Dr Anne Quain is a lecturer at the Sydney School of Veterinary Science and a practising veterinarian.
- DRFELT, S., MAYER, C., WOLF, G., STRAUBINGER, R. K., FISCHER, A., HARTMANN, K. & DRFELT, R. 2023.
- Retrospective study of tetanus in 18 dogs-Causes, management, complications, and immunological status. Frontiers in Veterinary Science, 10: 10.3389/fvets.2023.1249833