Malene Thyssen,
Wikipedia commons, you had more horse feces images than I knew I needed. Thank you.
I haven’t ridden in years, but if the “arena snot” and state of the duster jacket I used to wear when I did were any indication, it’s not the cleanest activity.

It didn’t stop me from enjoying a beverage or a burger after. I used to be awful at washing my hands before FSQA got it’s hooks in me. But since we covered eating something distributed by people at the derby, why not explore the real attraction and what they may be flinging up in the stalls.

Everybody poops

Churchill Downs apparently produces 30 “truckloads” of manure and soiled bedding every week. Anyone who’s ever played Frisbee with a cow chip also knows that when dry, the stuff crumbles into a fine dust that can reasonably go everywhere. So while “living in a world covered in feces” is not always an accurate headline, the dusty air of the racetrack has probably got to be one of those areas where it’s partially true.  While no major outbreaks have ever been directly attributed to horse contact, petting zoos that presumably contain equids have been implicated in many.

The good news here is that while there is certainly plenty of fecal-oral transfer to be had in a venue like this, there are not going to be many sick animals. A sick horse is a huge liability to the owners, facility, and Kentucky equine industry, and they don’t screw around. On arrival, horses enter strict quarantine before being permitted onsite. Horses flying in from outside the country are kept in steel crates until transported to a special quarantine barn with better bio-security than any university micro lab I’ve ever seen. So just like one would hope the catering at a food safety conference would be properly vetted, the truckloads of manure leaving the track are presumably carrying fewer pathogens than your average manure pile.

So what’s in all of that waste that could potentially make us sick?

Roll call!

Salmonella spp.

While everyone always wants to blame the birds for Salmonella, it’s apparently extremely common in horses. The national prevalence of fecal shedding of S. enterica by normal horses in the USA is estimated to be <2%, but the proportion of hospitalized horses shedding is much higher at ~8%. These subtypes are often the same ones we ourselves love to eat, and thus if you’re treating a horse for salmonellosis you should take precautions in the same way you would for a human patient. These are the boring ones:

  • Protective clothing
  • Prevent cross-contamination
  • Personal hygiene

Woo. Sub-clinical Salmonella bacteria shedding has also been reported in horses, so it’s still possible that in that environment it could still be found hanging out despite all the quarantines. Or maybe you just can’t keep a certain horse from preparing meals for everyone, even though it’s shedding bacteria; it’s just stubborn that way.


Even though we are starting to realize just how common Campylobacter is, there’s not a lot of testing for it in food safety circles. It isn’t particularly deadly in healthy populations, but more and more we’re starting to see it in animal vectors. It’ll be interesting to see where Campy ends up on food safety radar in the next few years.

Methicillin-Resistant Staphylococcus Aureus (MRSA)

While often discussed with respect to wound infections, MRSA is also responsible for food-borne Staph intoxication when it is allowed to proliferate in foods. We also know that transmission between people and animals is probably common. If someone has a lukewarm crockpot full of biscuits and gravy or a heat lamp on something moist near the track, tell them to stick a thermometer in it, or pass it by.

Cryptosporidium parvum

Crypto doesn’t have any sort of intermediate host in its parasite life cycle. It’s very happy kicking out eggs and reproducing inside a single host, which promotes re-infection in dirty conditions. While normally associated with drinking water, an infection rate of 71% has been reported in foals, and various asymptomatic shedding rates have been reported. It’s assumed that due to the high infection rate in foals that Crypto may not pose much of a problem for healthy horses. This means it may not be on the radar for the quarantine watchers like other disease would be. The oocysts are also strong survivors in the environment and are very resistant to chlorine.

This one could be an issue.


All in all, no matter the unique risks presented by this event, the same preventive measures hold true. Hygiene, cooking/chilling, protecting food from contamination (like feces-laced track/arena dust), and making sure workers follow good handling practices will do more for food safety at the track than any blog post or lit review.


Helpful sources for this article:

Weese, J. S. “A review of equine zoonotic diseases: risks in veterinary medicine.” Proceedings of the Annual Convention of the AAEP. Vol. 48. 2002.

Washington State University IACUC. “Zoonoses associated with horses. 2016

Oregon Veterinary Medical Association. “Zoonotic Diseases & horses. 2015

Centers for Disease Control and Prevention National Center for Emerging and Zoonotic Infectious Diseases. Scott Weese. “Horses”. 2014

American Trails. “Diseases of Humans and Horses (Zoonosis)”.