Tetanus is a neurotoxin caused by the bacteria Clostridium tetani, which lives in the soil pretty much everywhere. Clostridium tetani likes to form spores that are very resistant to heat, drying, chemicals, and fire-breathing dragons. Ok, I got a little carried away there… but seriously, this bacteria can survive for years in the environment. More bad news: it is particularly common in horse manure. You know where you can find plenty of that? On horse farms!

    Tetanus becomes a problem when it enters the body, usually through a wound or surgical incision. It is a myth that tetanus comes from sharp metal objects… it’s just that sharp metal objects tend to cause wounds which serve as a perfect entry point for this bacteria.

   Once the organism enters the body, it begins to multiply *evil cat laugh*. Clostridium tetani loves anaerobic (oxygen-poor) environments, like the inside of a wound. The tetanus toxin travels through the bloodstream and binds to nerve endings at neuromuscular junctions. The toxin signals the muscle to contract, and the muscle gets locked in the contracted position.

    What this looks like is a horse with all 4 limbs stiffened (often called a “sawhorse” stance), a tight or locked jaw, and the third eyelid flashing across from the corner of the eye. The horse may be lying down with all 4 limbs extended, unable to stand. Eventually the tetanus toxin binds to the muscles used to breathe, leading to death.

    In short, Tetanus looks very scary. Horses usually begin exhibiting signs within 24 hours of infection. The disease can progress over days to weeks, but is over 50% fatal. In order to survive tetanus, a horse must be rapidly treated with tetanus antitoxin, and managed with intensive supportive care (read: $expensive$). Even with treatment, horses often have long-lasting deficits from the tetanus infection.

   If you suspect your horse may have tetanus, call your veterinarian immediately. Better yet, you should call your vet any time your horse suffers a wound that breaks the skin.

   If your horse’s hooves ever touch the ground, then yes, he is at risk. If your horse lives on a horse farm full of tetanus-laden horse manure, then he is definitely at risk. If your horse lives on a horse farm, goes outside, and has access to sharp objects he could potentially cut himself on (this basically describes every horse I’ve ever met, and this cat has met a lot of horses), then he is at high risk for being exposed to tetanus at some point in his life.

   In fact, as a human you are also at a pretty high risk of contracting tetanus. This risk is increased if you spend time outside and at the barn, which most of our clients do with most of their free time. If you are a human, you probably received a series of tetanus vaccines as a child. Even so, you will probably receive a tetanus booster vaccine if you have a serious wound and have not been recently vaccinated against tetanus.

    “But Tony,” you may ask, “humans only need a tetanus booster like once every 5 years. Why do horses need boosters every 6 months?” Well, there are the high-risk factors discussed above (living outside in the dirt, having manure that is naturally full of tetanus). Then there is also the fact that nobody has ever studied exactly how long the protection of a tetanus vaccine lasts in horses. If you have a spare million dollars sitting around, you are welcome to fund such a study. Until then, I’m going to continue to err on the side of caution and recommend you vaccinate your horse once every 6 months.

   I thought you would never ask! Conveniently, there is a simple, inexpensive vaccine that is very effective at preventing tetanus in horses. Our docs recommended the vaccine twice a year in case your horse suffers a puncture wound or laceration. If we perform a surgery (such as castration) we will want to make sure your horse has been vaccinated against tetanus within the last 6 months. Reminder: that’s not because the docs dip their scalpel blades in Clostridium tetani before your horse’s surgery. It’s because cuts, even clean surgical ones, create a route for this bacteria that lives all around us to get inside the body.

    When it comes to tetanus, an ounce of prevention is worth a pound of cure. Since the disease is often fatal, and treatment is very difficult, we feel strongly that it is well worth a $20 vaccine. For this reason, many of the combination vaccines we give include tetanus. Tetanus is the “T” in “EWT-WN” (Eastern/Western Encephalitis/Tetanus/West Nile) and “EWTR-WN” (Eastern/Western Encephalitis/Tetanus/Rhino virus/West Nile) vaccines. It just so happens that these other vaccines are also recommended every 6 months, so why not lump them all into one poke? If that’s not your style, and this post has inspired you, we do stock the plain Tetanus vaccine at the clinic as well.

    So let’s all remember to call Shannon or MJ at the office to check when our horses are due for a tetanus booster, mmkay? Now I think I’ll go walk through some lovely tetanus-laden horse manure, and roll in some tetanus-flavored dirt! While I’m doing that, why don’t you scroll down a bit and subscribe? I’ll let you take a selfie with me at the next seminar if you do.

Until next week,

      -Tony