Dog owners worry significantly about tick infestations in dogs. There is a reason for this, as a dog is quite a tick magnet due to its height and fur. Mosquitoes, on the other hand, are much less of a concern.
People fear so-called medicinal repellents due to their supposed side effects. The fact that side effects are quite rare does not change this perception. Instead, people seek natural and non-toxic alternatives, forgetting that these do not repel, and some, like tea tree oil, are actually toxic to dogs despite being natural.
This is quite simple. Ticks and mosquitoes are driven by the need to reproduce, and they do not abandon their survival needs based on what kind of air fresheners are hung on a dog. Just because something is toxic to ticks, mosquitoes, and gnats, does not automatically mean the same substance is toxic to dogs or their owners.
There are two things to consider in products touted as natural — they are not even repellents:
- their effectiveness does not need to be proven or demonstrated
- Fimea supervises medicines, not such over-the-counter products
A manufacturer in Finland is marketing synthetic fragrance and flavoring as a natural repellent suggests that the permit required by chemical safety authorities is proof that the substance repels. It is not. That certificate is needed because industrial chemicals are used in the manufacturing process. The certificate ensures that the manufacturing process does not kill workers or harm customers. Quite a different matter.
Between products perceived as medicinal and those claimed to be natural are repellents not considered toxic: mosquito and tick scarves.
Because the repellent is in the clothing, it is not viewed the same way as if you poured a pipette on the neck, pushed a pill down the throat, or sprayed off into the fur. Yet they are entirely equivalent repellents, but the repellent is hidden in the fabric.
Permethrin is most often used, but for dog products — at least by one or two manufacturers — a synthetic compound IR3939 is used.
Although tick/mosquito scarves have not been on the market for long, the concept is already 30 years old on the human side — so it is not a completely outdated concept.
Repellent Clothing for Humans
Permethrin-protected clothing was first introduced in the United States in the early 1990s. They were expensive to manufacture — which is likely always the case with U.S. military procurements — and the protection could not be renewed once it wore off.
The technology developed and became more affordable, and ready-made permethrin-treated clothing entered the consumer market after the 2000s. Tick and mosquito scarves and sleeping pads for dogs began appearing in advertisements about 10 years later.
The repellent used varies, but is most often permethrin. Probably because DEET can be more irritating to the skin, and permethrin has slightly lower environmental impacts. Later, IR3939 also entered the market, mainly due to licensing by its developer, Merck.
The Repellent is in the Fabric
There are several ways to get the repellent into the fabric. The material may be simply treated with the repellent. It may be in the fabric as a polymer-protected or microencapsulated form. Or the repellent is sprayed on afterward, but this is quite different from what the manufacturer does.
The method affects how well the repellent in the fabric withstands sunlight’s UV rays and washing — or rain. Especially the sun quickly destroys the protection, but actual evaporation also occurs. Therefore, protection applied directly to the skin or dog’s fur generally repels for only 2 – 8 hours, at least when it comes to mosquitoes.
Washing and Sunlight Diminish the Repellent
Richards et al. (20171) investigated at the laboratory level — which can be considered theoretical compared to more rigorous practice — the effectiveness of permethrin added to the fabric during manufacturing against mosquitoes, taking into account washing, sunlight, and temperature variations on jeans and work shirts.
Freshly unpacked jeans had the most effective protection, which is perhaps expected. However, protection against mosquitoes quickly collapsed when washing and sun exposure were included.
Connally et al. (20192) tested how washing and wear affect tick protection.
Four test subjects wore permethrin-treated clothing and shoes twice a week for eight weeks. The clothes, except for the shoes, were washed after each use. Then pieces of the clothing were cut and tested for their effectiveness as repellents under laboratory conditions.
In the laboratory test, as in this study, a piece of fabric is placed at a 45-degree angle or on a flat surface, and the activity or unusual behavior of ticks is observed. They never test whether the ticks have an appetite after crossing the repellent-treated surface. Or whether they die.
Use and washing had significantly weakened the protection, but some repellent effect remained.
- the amount of permethrin had decreased by 50 – 90% in washed clothes
- in the test, 31 – 67% of ticks moved normally even an hour after exposure, whereas normally the percentage without repellent is around 90
So in the worst case, there was hardly any permethrin left after use and washing, and more than two out of three ticks were not repelled.
The American consumer organization Consumer Report tested four repellent-treated shirts priced at about $80, or about 75 euros depending on the exchange rate, against mosquitoes (20163). Manufacturers promised that the garment would protect against mosquitoes for 70 washes. The organization washed the shirts 25 times, put them on volunteers, and placed them in a cage with mosquitoes.
None of the shirts, which were supposed to be only halfway through their lifespan, were effective against mosquitoes. And interestingly, each of the four manufacturers also advised using a separate mosquito repellent with the mosquito-repelling shirt.
The common factor in all methods, regardless of how the repellent was added to the clothing, is that once the repellent is gone from the fabric, it is gone. And the disappearance of the protection is not only due to use and washing but also to storage time and display conditions.
When half a dozen consumer products were examined, none met the requirements set by the military for mosquito and tick protection (Faulde et al. 20164). Whether consumer products need to provide as good protection as military gear is another matter.
When a dog’s mosquito/tick scarf is hanging on a rack in the store as it is, you can be reasonably sure that there is not much protection left, if any. It has evaporated into the store’s indoor air and onto curious fingers. So if you buy one, take a scarf from the back for yourself.
As a side note. Several manufacturers advertise that the World Health Organization (WHO), a United Nations agency, recommends some repellent. In fact, this does not mean that the product repels domestic ticks, mosquitoes, gnats, and midges.
It means two things:
- the product repels malaria mosquitoes with some effectiveness
- the repellent does not pose a poisoning risk to humans and the environment
Therefore, DDT is not recommended by WHO, even though it is perhaps among the most effective at killing malaria mosquitoes.
Tick Repellent for Clothing
To claim that treated clothing repels and occasionally kills ticks, there should be evidence for the claim. Of course, some research has been done on repelling, especially concerning mosquitoes and other flying insects, but the evidence should be public and specifically address ticks.
DEET, along with Bayer’s 1990s development of Icaridin (known as picaridin in North America), effectively repels mosquitoes but is weaker against ticks. IR3939 is even more complicated, as although it is accumulating promising evidence, the studies appear to be strongly linked to the pharmaceutical company Merck, and the research settings are favorable to it.
There is little publicly available research data on the benefits of repellents added to clothing. They repel mosquitoes if there is any repellent in the clothing at all. Spraying the entire outfit with Off during mosquito season is not a new idea. But does it help against ticks? It seems that it might.
How does this relate to dog tick scarves? Unfortunately, only theoretically. Research indicates that repellent can be attached or added to clothing. But studies do not provide any information on the benefits of tick scarves, and in fact, everything known strongly argues against the use of tick scarves.
Sawyer’s Advertisement
Sawyer, perhaps better known for water filtration for hikers, also manufactures insect repellents. One such product is permethrin spray for clothing. Sawyer states in their advertisements that the repellent effect lasts either six weeks or six washes, whichever comes first5.
Sawyer promises hikers 73.6 times better protection if their spray is used to protect shoes and socks. The number is impressive, but it doesn’t mean anything by itself. One would need to know how many tick bites would occur without it. In reality, this number means that about one in three ticks crossed the permethrin-treated area in laboratory tests or got stuck in a permethrin-treated drum. And the fact that one in three ticks doesn’t care doesn’t sound quite as good.
Now we’re straying a bit from the topic, but one should also know how many ticks jump on from a blade of grass, and then find out how many give up the attempt because of permethrin. You get one guess how many such studies have been done… Exactly. There aren’t any.
But we’re interested in dogs. According to Sawyer, permethrin treatment protects dogs against fleas and lice for 35 days and against ticks for the same magical six weeks as humans. So a slightly longer protection against ticks than other external parasites.
However, Sawyer does not advise using permethrin on gear, as with humans, but directly on the fur in the traditional way6. So the manufacturer, which specifically advises treating the owner’s clothing, does not suggest scarves for dogs or sleeping pads. The reason is clear. The repellent does not spread to the dog’s fur from a neck accessory, and ticks can still hitch a ride on legs, belly, sides — or head.
Miller et al. 2011
The 73.6 times better protection against tick bites promised by Sawyer when shoes and socks are protected with permethrin is not pulled out of thin air. The claim is based on the study by Miller et al. (20117).
It examined the overall effectiveness of permethrin when applied to clothing, and indeed it worked. It has long been known that permethrin is reasonably effective at repelling ticks. Although the study compared manufacturer-applied permethrin saturation with self-sprayed, the study focused specifically on whether permethrin helps when applied to clothing. Not whether there are differences between manufacturers’ techniques. These are two different things.
In the study by Miller et al., there were 15 people who dressed in a summer style, i.e., light cotton t-shirts, shorts, and Converse sneakers (of course Converse, what else).
The clothes were either treated with Sawyer spray two days before the study or pre-treated with the manufacturing technique of Insect Shield company. The sneakers were always treated with Sawyer’s product a day before the study.
A new set of clothes was used on both days of the study, not those used the previous day.
So the group was divided into three, with five people in each. In the study, no one used the same repellent or none the next day, so each test had 10 person-uses.
The test subjects were not exposed to tick-borne diseases, but a bred strain was used. Each was placed with 10 nymphs per test in different places and observed how many progressed, bit, and either gave up or died.
Each was placed with 10 ticks in three different places:
- on the shoelace of the left foot
- above the right knee
- above the left elbow
Since the test was conducted over two days, 300 tick nymphs were used per test.
The subjects sat on a chair under which was a white flannel cloth. This made it easy to find fallen ticks.
The ticks were placed in a cotton pad, model makeup, and it was attached above the knee and elbow. The ticks were transferred directly to the shoelaces. After 15 minutes, the pads were removed, and if a tick had not moved to the skin, it was assisted with tweezers directly to the target.
The test subjects sat for another 10 minutes, and then some physical activity was introduced. They sat, stood, walked in place, and stretched for 5 minutes. This was repeated every 20 minutes until 2 hours were up.
Every tick that fell to the flannel on the floor was classified as unattached, one that had not bitten.
Attached ticks were removed, and the bite location was recorded. At the same time, it was determined whether the tick was alive or dead — this decision was always made by the same person by looking through a magnifying glass to see if the legs moved. If there was movement, the tick was considered alive. If not, it was counted as dead.
On the first test day, most of the attached ticks in the permethrin groups were dead. This was mentioned anecdotally, but I would have been interested in at least some speculation as to why the number of dead attached ticks was lower on the second day with the same treatment.
The results in repellent effectiveness are interesting. Let’s forget this time how many times more something was than something else, and look at the direct numbers. Generally, probabilities should be discussed, not coefficients, but that is, of course, a matter of taste.
10 people and a total of 300 ticks. There were thus 100 ticks at each of the three attachment sites. Let’s see how many ticks bit:
| Without protection | Spray | Cloths | |
|---|---|---|---|
| Shoes (+socks) | 27 | 1 | - |
| Knee (shorts) | 55 | 17 | 24 |
| Elbow (t-shirt) | 64 | 56 | 34 |
Shoes were not a comfortable surface for ticks. First, they had to navigate the shoelaces to the top of the shoe and then along the sock to the bare skin.
People who were untreated got bitten by just under one in three ticks. But two out of three ticks gave up.
When permethrin was sprayed on the shoes, only one out of a hundred ticks reached the target. This then leads to the 73.6 times better protection advertised by Sawyer.
From this, one could quickly conclude that protecting the shoes would be the most effective. Of course, according to the study, it is, but ticks rarely lie in wait so close to the ground.
The researchers suggested that the ticks received an immediate dose of permethrin, which had an effect. Others received a dose of permethrin at the earliest after moving off the makeup pad, which easily took 15 minutes.
It may be that the explanation lies in both factors, the material and direct exposure to permethrin. But other tests have directly tested permethrin, and there has not been such a large difference. So monitoring from knee height may be closer to the truth, or reality.
When ticks were placed immediately above the knee, i.e., they were bothered by the shorts’ protection, the situation became more interesting.
Without repellent, slightly more than half bit into the skin. So according to the study, it is a coin toss, slightly weighted with heads and tails, whether you get a tick or not.
The permethrin added to the fabric by the manufacturer did better, with only one in four sinking its head into the skin. But if it is stated that despite expensive and high-quality permethrin-containing shorts, one in four ticks crawls to a meal along the warm thigh, it doesn’t sound quite as pleasant.
Sprayed permethrin performed slightly better than the manufacturer’s woven: 17 out of a hundred ticks bit. Or slightly less than two out of ten.
Hands usually flail a bit too high for ticks, but they can still pick up hitchhikers. When crawling through tall grass or bushes, without protection, two out of three managed to get under the t-shirt for a meal.
In terms of numbers, a tight, smooth-surfaced long-sleeved t-shirt would be the best protection if considering clothing alone. But there may be a similar distortion affecting shoes as well.
The tick wants to get to a meal as high up as possible in a sheltered and warm place where there are blood vessels nearby. Then from elbow height, the shortest distance to the feeding point reduces the risk of falling along the way.
When permethrin was included, the repellent effect was not as overwhelmingly great as one might have expected.
When permethrin was sprayed on the clothing, slightly more than half of the ticks managed to bite. The difference from being without protection was not very large.
One can guess that when a permethrin-sprayed t-shirt does not prevent much under the shirt. But if the shirt has not been soaked through, the spray does not repel underneath the shirt either.
When the solution packaged by the clothing manufacturer was used, the effectiveness was somewhat better. About one in three ticks bit.
The reason may be inversely the same as why sprayed Sawyer’s permethrin was not effective. When the repellent is encapsulated in the fabric’s weaves, it is released in all directions — including inside.
But why was the t-shirt still significantly worse than the shorts? Now one would need to know the clothing models. Because if the shorts were of the cycling type, and the t-shirts more open hip-hop style, then the freer routes for ticks explain a lot.
Why Scarves Don’t Help Dogs?
If we forget that scarf manufacturers do not disclose how the repellent is applied, often not even the amount, the ineffectiveness of a dog tick scarf comes from the same reason as in human clothing. The repellent embedded in the fabric does not spread.
It is exactly the same as swiping off behind the ear like a bicep and firmly believing that the ankles won’t get bitten.
Tick scarves benefit the dog only in the neck area, nowhere else. The same applies to mosquito scarves. However, dogs get their ticks from their limbs, belly, tail, ears, and snout — and these are unprotected.
This applies just the same as to all other alternative reality products. If a dog uses fragrances or a tick scarf, mosquito scarf, or even a mosquito-protective sleeping pad, then the owner should also wrap a bandana around their neck, swipe a dab of lavender behind the ear, chew a clove of garlic, and then venture into the heather with a bare bottom — then we can discuss again whether naturalness is a better option than industrial chemistry.
Even the white amanita is immensely natural. And the lily of the valley. And daphne.
- Richards, Stephanie & Balanay, Jo Anne & Harris, Jonathan & Banks, Victoria & Meshnick, Steven. Residual Effectiveness of Permethrin-Treated Clothing for Prevention of Mosquito Bites Under Simulated Conditions. Journal of environmental health 2017. 79. 8-15.[↩]
- Neeta P Connally, Dominic A Rose, Nicole E Breuner, Robert Prose, Amy C Fleshman, Karen Thompson, Lisa Wolfe, Corey D Broeckling, Lars Eisen, Impact of Wearing and Washing/Drying of Permethrin-Treated Clothing on Their Contact Irritancy and Toxicity for Nymphal Ixodes scapularis (Acari: Ixodidae) Ticks, Journal of Medical Entomology, Volume 56, Issue 1, January 2019, Pages 199–214[↩]
- https://www.consumerreports.org/insect-repellents/permethrin-treated-clothing-mosquito-bites/ status 8.6.2022[↩]
- Faulde MK, Pages F, Uedelhoven W: Parasitology Research, 2016, vol. 115, n 4, p. 10.[↩]
- https://www.sawyer.com/products/permethrin-fabric-treatment status 8.6.2022[↩]
- https://www.sawyer.com/page/dogs-and-permethrin-insect-repellent status 8.6.2022[↩]
- Miller NJ, Rainone EE, Dyer MC, González ML, Mather TN. Tick bite protection with permethrin-treated summer-weight clothing. Journal of Medical Entomology. 2011 Mar;48(2):327-333.[↩]