(WHTM) — Once upon a time (specifically the 1970s), in a beautiful faraway country (specifically Switzerland), it rained chicken heads.

The reason for this peculiar precipitation? Our old friend, Vulpes vulpes, is the red fox. Foxes are a rabies vector species, and at the time, they were vectoring like crazy through much of Europe.

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The only way to stop the spread was to vaccinate the foxes. But, trapping and vaccinating them by hand just wasn’t practical. But what if the foxes could vaccinate themselves?

That’s where the chicken heads come in. Before being dropped from planes and helicopters, they were filled with oral rabies vaccine.

The foxes were most approving of the free meal and gulped the chicken heads down wherever they found them. The number of vaccinated foxes rose, the number of rabid foxes dropped, and by 1996 Switzerland was effectively free of rabies.

The use of oral rabies vaccines has spread worldwide, including here in the United States. the U.S. Department of Agriculture handles the task of air-dropping the bait packets.

Today’s baits are little plastic containers of vaccine coated with fish meal-much more convenient and much less messy than chicken heads.

The U.S.D.A. works with a number of states, including Pennsylvania, dividing the country into zones that concentrate on different wildlife species. Here along the east coast, the species we’re most concerned with is the raccoon.

Many of the baits get dropped in the western half of the state, in the Appalachian mountains, to create a barrier against the westward spread of raccoon rabies.

A word of warning, though, if you’re thinking it would be a great idea to just get ahold of some oral rabies vaccine packets and toss them into the woods yourself, forget it. We checked in with the Pennsylvania State Game Commission about it, and Commission veterinarian Dr. Andrew Di Salvo sent us a statement explaining in detail why this is a job best left to the pros:

“It is illegal for any citizen in any state to administer medication, including vaccines, to free-ranging, wild birds or mammals without authorization from the proper wildlife management agency. Vaccination campaigns for wildlife have been pursued in the past (e.g., the endangered black-footed ferret and the plague vaccine) but all work has traditionally been performed by personnel from federal and state wildlife management agencies as they are the authority over such wildlife. Federal regulations, particularly the Animal Medicinal Drug Use Clarification Act, require a veterinarian to establish a veterinarian-client-patient-relationship or VCPR before prescribing any extra-label drug use in any wildlife. Veterinarians other than myself can establish VCPRs and administer drugs to wildlife in PA as part of the research, but that can be done only after securing permission from us in the form of a permit.

“This issue has come up in the past with citizens wanting to treat mangy wildlife that they encounter with ivermectin. While folks’ hearts may be in the right place, there are problems with the idea. In addition to lacking our permission, there is no vet oversight, no VCPR, and no official diagnosis occurring. Ivermectin is and can be lethally poisonous to many mammals (including breeds of domestic dogs!) and ensuring that the target wildlife species is consuming it is challenging. The same goes for any other drug placed into the bait. Furthermore, wildlife that receives drugs, whether via bait, dart, or syringe, need to be marked (e.g., ear tagged) to signify that they’ve received drugs. This allows tracking to determine if the proper amount of time has elapsed for drugs or any drug residues to be eliminated by the wildlife before they enter the human food chain.”

It’s possible, of course, to chance upon an oral rabies vaccine bait out in the open. What should you do? According to the Pennsylvania Department of Health, the best thing to do is just leave it alone, “unless the bait is on your lawn, driveway, or another area where a child or pet might find it. In that case, move it to a wooded area or other location with a thicker cover. Wear gloves or use a plastic bag or paper towel to protect your hands. If you need to dispose of the bait rather than move it, place the bait in a bag. Cover the bait with 1:10 dilution of household bleach, wipe down affected areas with the bleach solution, and place cleaning materials in the bag with the bait. You may then dispose of the bag in the regular trash. Wash your hands thoroughly with soap and water afterward.”