Fearing overseas radiation, Americans seek potassium iodide for pets

Veterinary experts say medication isn’t warranted

March 18, 2011 (published)
By Edie Lau

For more evidence that people love their pets like family, consider the latest reaction in America to Japan’s nuclear crisis:

Especially in western states, agitated pet owners are hitting veterinarians with requests for potassium iodide, a medication that may protect the thyroid gland from cancer caused by exposure to some types of radiation.

Their fear is kindled by radiation leaks from nuclear reactors in Japan damaged by a massive earthquake and tsunami last Friday.

A message board of the Veterinary Information Network (VIN), an online community for the profession, filled quickly this week with posts such as these:

“We have received multiple calls from frightened clients here in Southern California who are concerned about a cloud of radioactive material reaching our shores from Japan. They want to know what they should do to protect their pets.”

“I live in Portland, Ore., and with the nuclear scare in Japan, I have some clients asking me about iodine supplementation for their pets.”

“Our local health food store ... (has) had several phone calls from pet owners wondering if they could/should give their dogs and cats potassium iodide to protect from radiation contamination from the leaking nuclear reactors in Japan. ... Apparently the weather systems are supposed to be moving air currents and potential radioactive particles from Japan over Western Canada, Montana and Wyoming. We are in Northern WY.”

“Client completely freaking out insisted on dose and was incredulous that I wasn’t freaking out, too.”

In Hawaii, some 1,500 miles closer to Japan than the mainland West, which is about 5,000 miles distant, the frenzy for potassium iodide is even greater.

“Because of our geographic location, we’re sold out. There is none. Anywhere. So that’s causing more panic,” said Dr. Eric Ako, executive vice president of the Hawaii Veterinary Medical Association.

Based on news reports he’s heard that suggest the medication may offer some safeguard against radiation exposure, Ako said he would be willing to dispense it to clients’ pets if it were available. “If I could find documented appropriate dose ranges ... yeah, I’d do it,” Ako said.

Other veterinarians have expressed a similar willingness to accommodate pet owners’ requests. But in the view of veterinary experts in pharmacology, toxicology and oncology interviewed by the VIN News Service, it’s unwarranted.

Besides the fact that significant radioactive fallout is unlikely to occur here from nuclear-reactor leaks in a faraway country, they say, the use of potassium iodide to protect against radiation exposure in dogs and cats is unproven and poses an ethical issue as well.

“People are certainly overreacting,” said Donald Plumb, Pharm.D, author of Plumb’s Veterinary Drug Handbook, the reference book everyone is reaching for to determine what levels of the drug, if any, are appropriate for pets.

“If potassium iodide is needed, it’s needed first for people and not animals, and there’s limited quantities of it,” Plumb said. “At this time, there doesn’t seem to be any reasonable way that pets should be getting this in the United States.”

Nor people, according to the U.S. Food and Drug Administration. “There is no public health event requiring anyone in the U.S. to take KI because of the ongoing situation in Japan,” the agency states on its website, referring to potassium iodide by its chemical abbreviation KI.

The body needs iodine to produce thyroid hormone, which regulates metabolism. The idea behind taking potassium iodide in a nuclear emergency is to prevent the body from taking up radioactive iodine in the environment.

In veterinary medicine, potassium iodide is used to treat actinobacillosis (woody tongue) and actinomycosis (lumpy jaw) in ruminants; and the chronic skin infection sporotrichosis in horses, dogs and cats, according to Plumb’s Handbook.

The reference book provides no information about dosage levels to counter radiation exposure.

“I don’t know that anybody knows what is a reasonable dose of iodine for dogs and cats to prevent damage from ionizing radiation,” said Dr. Sharon Gwaltney-Brant, a toxicology consultant at VIN formerly with the American Society for the Prevention of Cruelty to Animals (ASPCA) Animal Poison Control Center. “The only studies ... have been done in humans.”

In the case of a true nuclear emergency and assuming supplies of potassium iodide were adequate to justify distribution to animals as well as people, Plumb said, veterinarians would be left to extrapolate from dosages for children the levels for veterinary patients.

(Dosages for children range from 16.25 mg every 24 hours for newborns; to 65 mg every 24 hours for youngsters ages 3 to 12.)

However, determining medication levels for pets based on human dosages can be tricky business, Gwaltney-Brant cautioned.

“We know that many times, the doses that work in humans aren’t the same as doses in dogs and cats,” she said. “There may be a difference in how they absorb it (and) how they eliminate it.”

Although potassium iodide is a form of the naturally occurring element iodine, the substance is not benign. In animals, Plumb’s Handbook lists the following adverse effects: excessive tearing, vomiting, anorexia, nasal discharge, muscle twitching, cardiomyopathy, scaly haircoats and dandruff, hyperthermia, decreased milk production and weight gain, coughing, inappetence and diarrhea. It notes that cats are more prone to developing toxicity.

Citing the potential side effects of taking potassium iodide, the University of California, Davis, which has a School of Veterinary Medicine, posted an advisory Thursday discouraging pet owners from giving their animals the tablets.

Other points to keep in mind:

• Potassium iodide does not protect against other types of cancers and health problems caused by radiation exposure, such as bone cancer, leukemia and cataracts.

• It is infants, children and immature animals who appear most vulnerable to thyroid cancer from radiation exposure because the cells in their bodies are dividing rapidly. Therefore, potassium iodide is most useful in protecting the thyroids of juveniles. “If you’re giving it to adults, you’re giving it as a placebo effect to calm them down,” Gwaltney-Brant said.

At Veterinary Specialty Center of Indiana, veterinary oncologist Dr. Michael Lucroy was prompted by news of the radiation scare to review what happened at Chernobyl, a nuclear power plant in Ukraine that partially melted down in 1986, spewing radiation through the countryside. The accident Chernobyl is, to date, still considered the worst commercial nuclear disaster in the world.

From reading a summary by the World Health Organization of Chernobyl's health effects, Lucroy determined that the only increase in cancers in the region clearly attributable to the power-plant contamination was thyroid cancer in people who were adolescents at the time of exposure.

“There wasn’t anything really I could find out about animal cancers in the area of Chernobyl,” Lucroy said.

He noted that giving pets iodine supplements in the absence of a clear need would put them at risk of overdose. “If you’re giving commercial pet food, plenty of iodine is in those diets, anyway,” Lucroy said.

The Associated Press reported Friday that radioactive fallout from Japan has been detected in California but so far, the levels are far below what is considered hazardous to human health.

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