No solid evidence behind all-natural parasite products

Vetted, Vetted January 2020, Volume 115, Issue 1

What can general practitioners say for sure about all-natural, organic veterinary parasite preventives? Richard Gerhold, DVM, MS, PhD, says not much.

With regard to the latest wave of organic parasite preventives, Fetch dvm360 conference speaker Richard Gerhold, DVM, MS, PhD, is skeptical.

“Although they can appear initially to be attractive substitutes for some other medications, unfortunately there's no solid evidence indicating their actual efficacy,” Dr. Gerhold says. “Given that keeping animals healthy also keeps humans healthy, in using those products you potentially seed an environment that could lead to not only an animal disease, but also a human health disease.”

CAPC on organic

The Companion Animal Parasite Council mentions “natural organic” products in a question in its pet owner FAQ at

Q: I am very concerned about chemicals around my family. Are there natural organic products that I can use to control fleas and ticks?

A: While there are some natural products that have a slight repellent activity against fleas, none have been shown to be very effective over the long haul. Eucalyptus oil, cedar chips and other aromatic oils may act as repellents but to have any effect at all they must be used very frequently and must be very fresh. This makes them a bit unpleasant to be around. Diatomaceous earth and Borax powder are very good drying agents and may be helpful in controlling fleas in the yard or even in the carpet. They can be a little messy but do help.

Dr. Gerhold says the only exception is for those managing backyard poultry, where entomologists have seen diatomaceous earth lessen mite infestations.

The website for the Companion Animal Parasite Council is a good place for GPs to send curious pet owners, he says, with its “science-based recommendations.” The veterinarian-facing website is; the pet-owner-facing website is

Dr. Richard Gerhold works in the Department of Biomedical and Diagnostic Sciences in the College of Veterinary Medicine at the University of Tennessee.

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