The Issue with Permethrin…

Thanks go to Daisy’s Human, Louise, for sending us this story in the hope that it will publicise the need to check exactly what you are giving your guinea pigs and to underline the fact that it should not be Permethrin! All medicines have side effects and all guineas will react differently and with varying degrees of sensitivity but where there is a safer option use it! Because guinea pigs are such small animals needing small doses usually medicines are often decanted into smaller vessels which may mean you are not automatically given the contraindications etc, ask for them, you are within your rights, even if you forget at the time, ring the surgery and ask or search for the product online, it will be there. NOAH Compendium ofAnimal Medicines is a good place to look.



“After discovering a light infestation of mites in my four piggies, I treated them with a spot on called Xenex Ultra. Unfortunately I had confused this with the treatment I had successfully used in the past, another spot on called Xeno 450. It was only later that I realised the Xenex Ultra contained the active ingredient Permethrin instead of Ivermectin.


The morning after treating the girls, they were all in a terrible state of anxiety, in particular Daisy. She was hurtling around the cage, screaming as if in pain. She kept banging into the walls and the other pigs. All of them were chattering their teeth and a huge fight broke out with her sister, Mabel.


I took Daisy to the vet immediately. I wasn’t even able to pick her up and ended up having to get her in the vet carrier by throwing a towel over her. The vet was very familiar with this terrible adverse reaction to Permethrin, which had caused Daisy to become so anxious, hyper-active and hyper-sensitive to light, sound, noise and touch. The vet informed the drug manufacturer but other than washing off any remaining spot-on, there was little else they could advise.


Over the next few days, we treated Daisy with Bach’s Rescue Remedy to help calm her down, but she basically lived under a towel in a separate area of the cage until the drug had worn off. It took about 5 days until she was happy to come out from under the towel and walk around normally. Sadly even several weeks after this happened, I’ve still not been able to successfully reintroduce her to Mabel, who she had the fight with the morning she was so poorly. After years of the girls happily living together, I think I might end up with having to keep them in 2 pairs. It’s very sad and I so much regret ever giving them the Xenex Ultra. I hope telling Daisy’s story will help to warn other people about the dangers of using Permethrin on their guinea pigs.”

The correct treatment for mites is to give an Ivermectin product, Xeno 450 for guineas over 800 gms and Xeno 50 for guineas under 800g are the correct ones, on day one and day ten and a bath in a Gorgeous Guineas’ shampoo as instructed.


Thanks to Gorgeous Guineas for these definitions:

  • Pyrethrum is a natural insecticide that comes from the flowers of specific species of Chrysanthemum.
  • Permethrin is a synthetic version of Pyrethrum with the chemical constituents based on those found in natural Pyrethrum. It is this synthetic version that is most often used in insecticidal products because it is far more stable in sunlight. Natural Pyrethrum breaks down in about 12 hours, but Permethrin is far more stable and longer-lasting at 30 days plus.

Read the Gorgeous Guineas’ blog post on this story here:

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