Japan's Nuclear Troubles: What is Radiation's Effect on Horses?


In the wake of the fourth explosion at the Fukushima nuclear power plant following the March 11 earthquake and tsunami, concerns continue to mount in regards to how much radiation could be leaking from the power plant and how it could impact the health and well-being of the area's residents. High doses of radiation can lead to radiation sickness in humans, but what types of effects might they have on horses?

Scientists note that in humans severe radiation exposure will have one of three effects:

  • Proves fatal within hours;
  • Causes certain delayed but fatal effects (such as bone marrow suppression or death from septicemia); or
  • Causes negative, yet treatable, gastrointestinal disorders (e.g., diarrhea).

What this means for horses residing near Fukushima is less clear, but according to Nathan L. Dykes, DVM, Dipl. ACVR (radiology), senior lecturer from the College of Veterinary Medicine at Cornell University in Ithaca, N.Y., the radiation's impact on area horses is likely minimal.

"I don't believe that the radioactive exposure levels are high enough outside the reactor buildings to cause either early or delayed 'radiation sickness,'" he suggested. "(The horses) would have to be within the exclusion zone of highest radioactivity to be affected directly."

Rachel Pollard, DVM, PhD, Dipl. ACVR, associate professor of diagnostic imaging at the University of California, Davis, School of Veterinary Medicine, Department of Surgical and Radiological Sciences added, "I am not sure that there is much literature about radiation sickness in horses specifically; however, the effects are likely the same as other species and are completely related to the dose the animal receives. The long-term effects are unknown, but I would suspect (exposed) horses would be more prone to cancer despite the relatively low incidence of cancer in horses."

According to Dykes, the amount of radiation the horses are exposed to depends on several factors:

  • Proximity to the accident (horses closer to the power plant will have a higher likelihood of radiation exposure than those further away);
  • The air they breathe (the difference between being housed indoors and outdoors, for example); and
  • The food they eat (grazing on pasture exposed to radioactive fallout vs. stored forage).

"I suspect that if animals are kept indoors and their forage is pre-disaster, then they are at no higher risk (for radiation sickness) than the people in the area," Dykes said. "If they are outdoors, closer to the event, and eating food from the ground, then their risk is greater. We could be looking at thyroid gland disease or tumors if the dose is high enough. But unless they are within a zone of extremely high radioactivity, these animals would not get radiation sickness as an acute event."

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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