Lufenuron: The miracle you may have forgotten

This article is sponsored by Merck Animal Health.

It is 1989 in central Florida, and a young veterinarian, barely 4 years out of school, is consoling another pet owner faced with the decision to either transfuse or euthanize her dog. The culprit is not cancer or immune-mediated disease. Instead, it is a flea infestation that is causing her beloved pet to bleed to death.

That veterinarian I described above was me, and such was an everyday scenario in my clinic— dogs and cats near death because of flea anemia or owners choosing to euthanize pets because of uncontrolled flea infestations in their homes. It seemed that no number of sprays, foggers, powders, baths, dips, or topical organophosphates could stop fleas. It was a challenging time to practice and an even tougher time to be a pet owner.

A game-changing product

It is not surprising that no other product, treatment, or procedure improved my practice like lufenuron. Introduced in the early 1990s, lufenuron was the first medication that could safely, effectively, and reliably break the flea life cycle, and end flea infestations. It was a miracle that I have never forgotten and have relied upon it to protect my patients ever since. As other products have come and gone, in my experience, lufenuron continues to work as effectively today as it did when it I first used it. In fact, some 30 years after its advent, no flea control plan should be without lufenuron at its foundation.

Lufenuron was developed by the agricultural division of Ciba-Geigy. It is a benzoylphenylurea, a family of chitin synthesis inhibitors and more broadly known as an insect development inhibitor (IDI).^1,2 By inhibiting the synthesis of chitin lufenuron stops flea eggs from hatching.^1,2

When administered systemically, lufenuron concentrates in the pet’s adipose tissue and is picked up by adult fleas during feeding.³ Lufenuron then affects the development of the larva in the egg, thereby preventing and controlling flea populations.¹

Versions of fipronil and imidacloprid were still a couple of years away. When lufenuron was administered to all pets within a household, the flea infestation was eliminated within 60 days.⁴ At the time, it was hard to believe, and I was very skeptical until I experienced it firsthand, again and again.

A closer look at adulticides

When the first adulticide medications later entered the market, veterinarians were distracted by the new, bright, shiny options. Although many practitioners experienced the miracle of lufenuron, they abandoned it and relied solely on adulticides.

The adult flea seen on the pet represents 5% of the life stages.⁵ The rest of the life stages are in the environment and frequently remain unseen.⁵ When an adulticide-only treatment was prescribed, clients were thrilled to quickly see fewer fleas on their pet but did not understand that they were only treating 5% of their problem. The thousands of eggs, maggot-like larvae and pupae already contaminating their homes were left to develop into adult fleas, needing to be eliminated one at a time as they emerged.

Eventually, the adulticide-only approach began to backfire. As flea populations were reduced, pet owners naturally began to apply adulticides only as needed instead of reapplying as directed. Beyond the dosing period these molecules continued to exist on the pet but are now at doses sub-lethal to the flea.

Isoxazolines

Today, veterinarians have access to isoxazolines, the newest generation of medications that work by killing adult fleas and ticks.⁶ By prescribing lufenuron and an extended duration isoxazoline, we get the best of all worlds; fast kill of adult fleas while preventing an environmental infestation.

My simple explanation to pet parents is that lufenuron will stop 2 fleas from becoming 2000 fleas in your home, while the isoxazolines will minimize the number of fleas you will see on your pet, a win-win!

Image: Merck Animal Health

Lufenuron is found combined with milbemycin in SENTINEL FLAVOR TABS (milbemycin oxime, lufenuron). Milbemycin affords a broad range of internal parasite protection, eliminating heartworms, hookworms, roundworms, and whipworms.⁷ Add praziquantel to control tapeworms and you now have SENTINEL SPECTRUM CHEWS (milbemycin oxime, lufenuron, and praziquantel), the 30-day, chewable preventive that protects against 6 types of parasites.¹ This product is remarkably affordable, safe, and includes lufenuron, the only systemic insect development inhibitor that prevents flea infestations.¹

Lufenuron might be that miracle you’ve forgotten, but the one you and your patients truly need.

Rick Marrinson, DVM, is the owner of Longwood Veterinary Clinic in Longwood, Florida and has provided care to companion animals in the central Florida area for over 36 years.

Important Safety Information:

SENTINEL SPECTRUM Chews (milbemycin oxime/lufenuron/praziquantel). Dogs should be tested for heartworm prior to use. Mild hypersensitivity reactions have been noted in some dogs carrying a high number of circulating microfilariae. Treatment with fewer than 6 monthly doses after the last exposure to mosquitoes may not provide complete heartworm prevention. For complete product information refer to the product insert. SENTINEL FLAVOR TABS (milbemycin oxime/lufenuron). Dogs should be tested for heartworm prior to use. In a small percentage of treated dogs, digestive, neurologic, and skin side effects may occur. For complete product information refer to the product insert.

References

1. SENTINEL SPECTRUM Chews [product label]. Madison, NJ: Intervet, Inc; 2020.
2. Zakson M., Hink W. Fate of the Benzoylphenyl Urea CGA-184699 in the Cat Flea Ctenocephalides felis. Pestic. Sci. 1992;35(2):117-123. doi:10.1002/ps.2780350204
3. Lufenuron Technical Profile. Virbac. 2016. Accessed December 3, 2021. https://www.animalhealthinternational.com/animalhealthinternational.com/media/Animal-Health-International/NSM16/Virbac/VirbacAH_Lufenuron.pdf
4. Dryden MW, Brown H, Buck S, Schwahn R, Sloan T, Summers S. Giving pets effective long-term protection against flea infestation. Vet Med. 1998;16-18
5. Halos L, Beugnet F, Cardoso L, et al. Flea control failure? Myths and realities. Trends Parasitol. 2014;30(5):228-233. doi:10.1016/j.pt.2014.02.007
6. Datz C. Isoxazolines. Plumb’s Therapeutics Brief. 2018;65-67. Accessed February 1, 2022. https://files.brief.vet/2018-03/PTB_TS_Isoxazolines.pdf
7. SENTINEL FLAVOR TABS [product label]. Madison, NJ: Intervet, Inc; 2020.