Pennyroyal, Dogs and Fleas
Answered by: Kerry Hackett
Question from: Terry Arnold
Posted on: May 01, 2007

I have a problem with fleas and have tried just about everything on the market. I have three dogs and moved into a home that had been infested with fleas. I have been told that the pennyroyal plant will help to eliminate the fleas. Do you agree or do you have any other sugestions?

Please see the postings on this website (www.richters.com) entitled, "Animals and Fleas", "Flea Repellent", "Fleas and Lemon Juice", Fleas on Dogs and in the House" and "Garden Herbs to Help with Fleas".

In addition, I do not advise the use of pennyroyal due to the following reasons:

1. Pennyroyal is toxic to cats (Schoen and Wynn, 1998)

2. Pennyroyal is toxic to dogs at high doses (Sudekum et al, 1992)

3. Because of its abortafacient properties, pennyroyal should not be administered to pregnant animals (Spoerke, 1990) Neither should it be used on lactating animals.

4. Pennyroyal should not be used in animals with existing kidney disease. (Schoen and Wynn, 1998)

5. As little as 4ml of pennyroyal oil has caused convusions in adult human subjects. Larger dosages can cause even greater problems. (Spoerke, 1990)

6. An infusion of dried pennyroyal leaves have been used as a stimulant, carminative and diaphoretic (Coon, 1979) but its toxicity may overshadow any therapeutic use.

7. Pennyroyal contains 2% volatile oil made up of 85% ketone and pulegone (Tyler 1993). Volatile oils are toxic to cats and dogs; see points 1 and 2 above.

8. Because of its toxic nature and the availability of other, milder bitter tonics, many herbalists recommend that pennyroyal be used only topically, with great caution. (Schoen and Wynn, 1998)

9. Although Ms Bairacli-Levy in her book "The Complete Herbal Handbook for the Dog and Cat" mentions (p. 155) the use of pennyroyal in powdered form on dogs before "mosquito-time", she does not advocate the use of pennyroyal flea collars ("... they would have to be renewed frequently to be effective."). Further in her book, "Cats Naturally", the use of pennyroyal is never mentioned beyond flea collars for which she says much the same as above (p. 76). She does however, talk of using Pennyroyal in powdered form on the carpet where it is brushed out after an hour.

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