Dogs Sniff Out Devastating Bee Disease Foulbrood

Written by Dr. Karen Shaw Becker

sniffing dog

Story at-a-glance -

  • Foulbrood is a deadly and contagious bacterial disease that can wipe out beehives and colonies
  • Inspecting commercial beehives for foulbrood is meticulous work that requires apiary inspectors to open up hives and physically look for evidence of the disease; dogs can be trained to sniff out foulbrood without having to open up hives
  • While a human inspector would need a whole day to inspect 45 hives for foulbrood, dogs can inspect 100 hives in 45 minutes
  • Currently, the Maryland Department of Agriculture is the only one in the U.S. using dogs for foulbrood detection, but a grant from the federal farm may help to expand the program into one that may one day be emulated by other states

With bee populations decreasing worldwide, it’s now more important than ever to protect bee colonies from devastating diseases like foulbrood. This bacterial disease is caused by a spore-forming bacterium called Paenibacillus larvae. Spores are spread to young larvae by nurse bees, causing the larva to die.

When other bees clean out the cell, they spread the spores throughout the hive, leading to death of more larvae. The hive’s honey also becomes contaminated with the spores, and if bees from neighboring hives come into the weakened hive to rob its honey, they bring contaminated goods back to their own hive, starting the devastating cycle over again.

What’s more, foulbrood spores stay in the honeycomb for up to 100 years, which means burning it and any infected equipment is among one of the only ways to stop foulbrood transmission. It’s largely because of foulbrood that hives are inspected prior to being transported across the U.S. to help pollinate crops.

One-third of the crops in the U.S. depend on bees for pollination, and many of them make a long trek from the east coast to California or from Maryland to states like Maine, New Jersey and Florida. “The tractor-trailers that carry hives across the country to pollinate crops are typically moving about seven million bees at a time. They are all vulnerable,” The New York Times reported.1

Dogs Make Ideal Candidates for Sniffing Out Foulbrood

Inspecting commercial beehives for foulbrood is meticulous work that requires apiary inspectors to open up hives and physically look for evidence of the disease. As reported by Bee Aware:2

“When inspecting for AFB [American foulbrood] beekeepers should remove each brood frame from the colony, remove bees from the frame and examine the brood frame for symptoms such as an irregular brood pattern, with a mixture of capped and uncapped cells.

Individual cells should also be carefully inspected for sunken, darkened and greasy looking cappings as well as perforated cappings (especially if perforations are irregular shaped or located on the edges of the cap).”

Dogs, on the other hand, can be trained to sniff out foulbrood, which often leaves a sulfur-like smell behind — without having to open up hives.

Cybil Preston, the chief apiary inspector for the Maryland Department of Agriculture, told The New York Times, “They can trot by, sniffing at the comb, and tell if the bacteria have killed off any larvae. Four people working full time cover less than half of what her dog can, Ms. Preston said.”3

Preston has rebuilt a canine detection program for foulbrood, starting with her dog Mack, a Labrador retriever who inspected 1,700 honeybee colonies in the fall and winter of 2017, even when the cold weather made the comb difficult to view. She’s also training another dog, her rescued springer spaniel Tukka, to join the program.

Her training involves sealing the dogs’ toys in a bag with foulbrood scent, then teaching them to retrieve the toys from increasingly challenging locations. Through play, reward and repetition, the dogs learn to detect even small amounts of the scent, then signaling its presence with a pointed nose and sitting down.

Mack’s training took nine months while Tukka’s is still ongoing, with four training sessions daily. “It’s a lot of time, but Ms. Preston reminds herself that once Tukka is up to speed, he will help her team cover more ground, work faster and more meticulously, and protect more honeybees,” according to The New York Times.4

Preston rebuilt Maryland’s canine foulbrood detection program after its original dog and his handler, the late Bill Troup, retired. In the video above, you can see Klinker, the first U.S. dog to be certified to detect foulbrood. The program was first started in 1982.

Do Colony-Sniffing Dogs Get Stung?

Beekeepers and inspectors wear an abundance of protective gear when examining hives, but Mack approaches them wearing nothing but his fur. This doesn’t put him in danger, though, because he primarily inspects during the cooler months, when the bees are quiet. Preston says he’s been stung only once or twice.

In Australia, meanwhile, which has also trained dogs to sniff out foulbrood, a special bee-proof suit was created to protect the dogs, including Elroy, a springer spaniel, and Bazz, a black Labrador. They also do their detecting primarily at night, when the bees are less active. According to Australian dog trainers K9 Centre:5

“The benefit of using a sniffer dog to detect AFB is that humans can’t detect the disease until the infectious scale has formed, but by this stage cross infection to other hives may have already occurred. If the dog can detect AFB in early stages less hives will be destroyed resulting in less loss of production. Also, the dog can inspect a whole apiary very quickly.

Trained dogs could be hired out at an hourly rate. It would take a human inspector a whole day to inspect 45 hives for AFB, but once trained Elroy will be able to inspect 100 hives in 45 minutes.”

Considering dogs’ impressive success in sniffing out everything from cancer and drugs to bombs and infectious diseases like clostridium difficile (C. diff.), it’s not entirely surprising that they’d also be rock stars at sniffing out foulbrood. Unfortunately, dogs are still a rare breed among apiary inspectors, something Preston is trying to change. "If we want to be efficient, we need a dog," she says.6

Currently, the Maryland Department of Agriculture is the only one in the U.S. using dogs for foulbrood detection, but Preston received a grant from the federal farm bill that will help her to expand the program into one that may one day be emulated by other states.7