Holistic vet Dr Iris Ege examines whether anti-parasitic flea treatments for our pets are a problem for them, those in close contact with them, wildlife and the environment. She goes on to discuss a possible protocol to follow

The current practice of giving the same flea treatment product on a regular basis is potentially problematic. In fact, there is increasing evidence that there can be significant adverse effects on:

  • The dogs and cats being treated
  • Those coming into close contact with treated animals such as family members, other household pets and groomers,
  • Wildlife
  • Habitats, particularly waterways and wetlands

Rivers and wetlands

Data recorded by the Environment Agency (EA) for 20 rivers in England between 2016 and 2018 was analysed by scientists at the University of Sussex. The results showed fipronil (commonly found in flea treatments such as Frontline and Itch It) was present in 99% of the samples (Perkins et al., 2021)1.

Furthermore, a particularly toxic breakdown product, fipronil sulfone, was measured at 38 times above the recommended safety level. The highest levels were found downstream of wastewater treatment works, with flea products likely to be entering the river systems via household drains.

The manufacturer’s webpage states: “Once applied, FRONTLINE … is stored in the sebaceous glands in your pet’s skin and spreads over the whole body surface with their natural oils. Fleas and ticks are killed through contact with your pet’s skin and coat …”. However, they don’t mention that it is also:

“Distributed throughout the body, including blood, brain, adipose tissue, and liver after dermal application,”

Perkins et al. (2021)1

Or that the liver is made to work harder to metabolise and detoxify it.

Both fipronil and the metabolite fipronil sulfone remain in the blood of dogs for a longer time than in mice. Fipronil alters the levels of dopamine and serotonin in the brains of mice and changes their emotional and cognitive behaviours. There is good reason to suppose it has similar effects on other mammals.


This is the active ingredient of, for example, the flea spot on Advantage as well as one of the active ingredients in the collars Seresto and the spot on Advocate. It is particularly dangerous for bees and its use has been banned in agriculture since 2018 (He et al. 2021)2. It too was found in the EA river samples.

There are also combination products containing Imidacloprid and Moxidectin that are used to prevent lungworm as well as fleas. Please note that you can test for lungworm using a 3 day pooled faecal sample (see the Holistic View of Worms and Worming blog).

Of fur, urine and blue tits!

Recent research shows that flea treatments can be found in the urine and hair of not only treated but UNTREATED dogs too and also in nests of blue tits, probably due to dog hair being used as nesting material. Even products given orally as tablets result in marked contamination of water that dogs swim in (Diepens at al., 2022)3.

Alternatives to chemical treatment

We often get asked about natural alternatives to flea treatments. Unfortunately, we have not found anything that works reliably for serious infestations and is safe.

Suggested protocol

1. Prevention is better than cure

If you can monitor your pets closely, we recommend a simple and effective check on a regular basis to detect flea infestations as early as possible. Comb your pet with a flea comb and get the hair and dirt samples off the comb using a moist white paper towel.

If you leave it for a few minutes you will find any flea dirt turning red. Please note that flea dirt can usually be spotted long before the first fleas are noticed.

Fleas live in carpets or bedding and only jump onto the pet to bite and return to the carpet/bedding to breed. A flea lamp can help detect them swiftly.

Likewise, check your dog for ticks regularly especially in high risk areas (see the CAM4animals tick blogs). Bear in mind there is a balance to be struck between the application of chemical treatments and the relative risk of Lyme Disease depending on the season and where you take your dog for a walk.

2. Only treat when necessary

We recommend treating ONLY when a flea infestation is present (or it becomes impossible to keep on top of tick attachment) and reserving preventative treatments to genuine high-risk situations which should be rare.

Where regular preventative treatments are unavoidable the following should be considered:

  • Lifestyle
  • Actual parasite exposure
  • Minimising adverse effects in the environment
  • The detox systems of pets and handlers

For example, using different products at correct intervals can minimise the extra strain on affected systems.

3. Grooming

In particular, the use of certain products on domestic animals is not recommended where handlers spend significant amounts of time grooming or handling treated animals (Tingle et al. 2003)4.

4. Environmental recommendations

If you have to use flea and tick treatments, please make sure you check for the manufacturer’s recommendations with regard to avoiding water since assessments have predicted a risk to birds, fish, and aquatic and marine invertebrates including endangered species (Tingle et al., 2003)4.

Other parasites

There are more tips for tick prevention on the website and for more details on wormers please see the A Holistic View of Worms and Worming blog.


  1. Perkins R, Whitehead M, Civil W, Goulson D. Potential role of veterinary flea products in widespread pesticide contamination of English rivers. Sci Total Environ. 2021 Feb 10;755
  2. He B, Liu Z, Wang Y, Cheng L, Qing Q, Duan J, Xu J, Dang X, Zhou Z, Li Z. Imidacloprid activates ROS and causes mortality in honey bees (Apis mellifera) by inducing iron overload. Ecotoxicol Environ Saf. 2021 Sep
  3. Diepens NJ, Belgers D, Buijse L, Roessink I. Pet dogs transfer veterinary medicines to the environment. Sci Total Environ. 2022 Oct 18;858
  4. Tingle CC, Rother JA, Dewhurst CF, Lauer S, King WJ. Fipronil: environmental fate, ecotoxicology, and human health concerns. Rev Environ Contam Toxicol. 2003;176:1-66.

Useful links

A Holistic View of Worms and Worming

Tick blogs


Find a vet at the British Association of Veterinary Herbalists website

Article by Iris Ege, Dr med vet, MRCVS, Cert Vet Ac
Iris grew up on a smallholding in Germany.  She studied Veterinary Medicine in Germany and graduated in 2003, she trained in Wings® Animal-Kinesiology and did her Practitioner exam in Aug. 2007. This enables her to access other complementary therapy forms, especially for chronic cases.

Iris qualified in international acupuncture training with International Veterinary Acupuncture Society (IVAS) in 2013.  She covers the fields of Traditional as well as Western Acupuncture and Low-Level Laser Therapy. As a result of qualifying as a veterinary herbalist and becoming a member of the British Association of Veterinary herbalists, Iris enhances or sustains the effects of acupuncture with herbs as well. She combines the scientific approach to herbal medicine with holistic herbal knowledge.  She also has an interest in nutrition and is a member of the Raw Feeding Veterinary Society (RFVS).

Iris has worked in general practice not only treating pets and horse but also cattle and goats holistically with good results. Acupuncture has become her main interest and in October 2012 she left mixed practice to focus on alternative veterinary medicine founding A.P. Vet Ltd in January to facilitate the team approach for the benefit of her patients.


Disclaimer – Where blogs have been created by a guest author, CAM4Animals has reproduced this in good faith but cannot be held responsible for any inaccuracies of information in it or any use you make of this information

This blog may also contain an element of consumer opinionWhilst CAM4animals welcomes positive recommendations for holistic healthcare products, we don’t necessarily endorse the product or the author’s opinion. We acknowledge that each animal is an individual and may react differently to the highlighted product/s. There may also be other products available that produce similarly positive results.

The veterinary Surgeon’s Act 1966 restricts the treatment of animals (usually other than your own*) by anyone other than a qualified vet. Always consult a veterinary surgeon if you are concerned about your animal’s health. *For full details visit the RCVS website