Breaking into beehive medicine

Honey bees may be thought of more as wildlife than food production animals, but they share substantive similarities with the latter when it comes to food supply, antimicrobial resistance, One Health, and even euthanasia concerns.

Dr. Kaitlyn Krebs, assistant clinical professor of primary care at the University of Pennsylvania School of Veterinary Medicine, urges all clinicians to educate themselves about this nascent area of practice. Dr. Krebs is not only a bee veterinarian but also a beekeeper.

Beekeepers know veterinarians don't have a familiarity with bees like they do with dogs or cats, she said. "Beekeepers are super nice people, and everyone is willing to help because there is a huge need for veterinarians to take care of these bees."

Dr. Kaitlyn Krebs, a honey bee veterinarian and beekeeper, stands near a teaching apiary at the University of Pennsylvania. She says when looking at the hive, it should be considered a colony or organism as a whole. (Photos courtesy of Dr. Krebs)

A federal rule that went into effect in 2017 brought veterinarians and beekeepers together when it restricted beekeepers from using certain antimicrobials in honey bees without a veterinary feed directive or prescription from a veterinarian.

Dr. Krebs gave three presentations at the AVMA Convention 2024, held June 21-25 in Austin, Texas, that touched on bee biology and bee health and common diseases, including, "A Veterinarian's Role in Bee Health and How to Get Started," to help her colleagues understand how to break into this area of veterinary medicine.

Physical examinations

She said that beekeepers should have notes to help practitioners with important information such as the queen's age, if the hive has swarmed, and if honey has been harvested from the hive. However, this may not always be the case, Dr. Krebs notes, or the records may be kept in an "interesting" way, such as placing bricks in specific positions that indicate the state of the hive during the last inspection.

Physically examining the hive involves good biosecurity, whether by using the beekeeper's own tools or using your own and disinfecting between apiaries. Dr. Krebs recommended wearing as much protective gear as the veterinarian feels comfortable with.

"Don't let them tell you (that) you don't need to wear gear," she said. "I have producers who go in with no gloves on. I do surgery and need to make sure I can use my hands and don't want puffy hands when I go in the clinic next day."

An example of a good brood pattern on a frame. The queen is visible in the center of the image.

Inspecting the hive starts with noticing the activity happening on the outside.

"I get worried when there is no activity at the front, or there's lots of activity one day and the next there is minimal activity," she said.

She shared other considerations as follows:

• The number of dead bees: The worker bees will drag bees that have died to the front of the hive. While some death is normal, increases are a cause fore concern.
• Brood health: What percentage of brood frames are covered? Eighty percent is a good amount. The bees help to keep the brood warm, so fewer bees raise questions about their health.
• Adult health: Pay attention to where the majority of bees hang out. Most of the time bees try to spend time at the bottom, rather than the top of the hive.
• Nutritional stores: Internally, look at the food stores in the frames. How full are the honey supers? Are they making honey and capping it? Where is honey being deposited? Is there pollen in the brood chambers?
• Queen cells: These could be an indication the hive doesn't have a queen. These are peanut-shaped cells that can happen anytime the hive is thinking of replacing or needs a new queen. If hive is swarming, they'll build queen cells.

"You are assessing the hive as a whole when you go through. As a veterinarian, you are not running the show, you are looking for specific things. Don't expect you have to find the queen, the beekeeper should be able to help you," Dr. Krebs said.

Veterinarians can look for evidence of the queen laying her eggs. She does that for the whole hive. If you see eggs, that means she's been there within the last three days.

Then it's time to look at the brood. When veterinarians conduct inspections, they should see all developmental stages of the brood/bee. Questions to ask are:

• Is there a single egg per cell?
• Do the larva have adequate nutrition?
• What is the quality of the capping on the capped brood?
• Are there any open cells?

"The queen lays in a concentric pattern. If it doesn't look like that, there could be a problem," Dr. Krebbs said, noting that a shotgun brood pattern may be a sign of disease. Instead, there should be a solid layer.

Antimicrobials and vaccination

Two diseases that can afflict bees are European foulbrood (EFB), Melisococcus pluton, which is a bacterial disease caused by stress, and American foulbrood (AFB), a spore-forming bacterium called Paenibacillus larvae.

These can be treated with three antimicrobials, oxytetracycline, tylosin, or lincomycin, all of which require a VFD or prescription from a veterinarian.

"If they need (antimicrobials) for something else, something has gone wrong," Dr. Krebs said.

One frame from the inside of a hive that includes a capped brood and the queen.

In its vegetative infective stage, AFB is susceptible to oxytetracycline, lincomycin, tylosin. In most cases, though, everything touched by AFB should be killed and burnt at the apiary site, if possible, within a week.

"It's devastating for beekeepers to lose a whole yard, all that time and bees. It's heartbreaking but also a loss of their livelihood," Dr. Krebs said. American foulbrood is a reportable disease, according to the U.S. Department of Agriculture's (USDA) Animal and Plant Health Inspection Service, so veterinarians need to know where to report and how often.

There is some hope, however. The USDA's Center for Veterinary Biologics granted a conditional license in 2023 for the first vaccine to protect against AFB, which is from Georgia-based Dalan Animal Health Inc. The vaccine is mixed in a "queen candy" paste, which is digested by worker bees. That substance is transferred to their glands that produce royal jelly, which is fed to the queen and transferred to her ovaries, making her larvae more immune to infection.

"It's not super widely available yet," Dr. Krebs said, and there's lots of research still being done on the vaccine. In tests, immune priming showed no negative impact on queen fitness. In fact, bee hives vaccinated against AFB had lower levels of an unrelated viral disease than did unvaccinated hives, according to results reported by a veterinarian at Dalan Animal Health during the 2024 World Vaccine Congress.

For EFB, on the other hand, there is no vaccine and the only Food and Drug Administration (FDA)-approved drug available to treat it is oxytetracycline.

Dr. Krebs recommends administering antimicrobials in sugar water or powdered sugar spread over the inside of the hive for the bees to eat and spread.

She says the antimicrobial must be removed at least six weeks before the main honey flow to prevent contamination of the honey. Otherwise, if treating during or after the main nectar flow, the beekeeper can't use any of the honey for human consumption during that time and at least six weeks later.

"Take all honey off the hive if treating in the summer and then treat with antibiotics. Or mark the frames you treated so you don't harvest them," she said.

Writing VFDs and euthanasia

To prescribe antimicrobials for these conditions, veterinarians must first establish a veterinarian-client-patient relationship (VCPR) with a hive and its beekeeper.

Just like any other animal, the veterinarian assumes responsibility for the patient, must have sufficient knowledge of patient and facility, and must provide necessary follow-up care.

"You can't just have a beekeeper call you and say they need antibiotics. Yes, there are not that many bee vets or those who are comfortable treating bees. But at the end of the day, it's your license and your responsibility to make sure you have sufficient knowledge of patient or facility," Dr. Krebbs said.

Small animal veterinarians may not be set up to do population health work or VFDs, but Dr. Krebs said forms online are very accessible that can help. These include a Healthy Colony Checklist from Bayer and a VFD template from the FDA.

If the honey bees need to be euthanized because of disease or emergency situations, there is currently minimal scientific data to provide clear guidance. More research is needed to provide evidence-based recommendations on killing bees in a humane manner.

"As a veterinarian, you're not required to do this, but we do have a responsibility to provide pain free death to these animals. It's important to be aware of," she said.

In general, veterinarians interested in this area of practice should educate themselves, whether by attending local bee clubs or shadowing beekeepers, and potentially starting their own hives.

"As a bee vet, you have to take an approach that really embraces One Health and the environment and the creatures that live within it," Dr. Krebs said. "A lot of this comes with experience, as do a lot of things in vet med. The more we do it, the more we get used to it."

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