# How does topical (non-systemic) anti-tic/flea dog goop cover the whole coat if applied in 6-8 dabs?

**URL:** <https://boards.straightdope.com/t/how-does-topical-non-systemic-anti-tic-flea-dog-goop-cover-the-whole-coat-if-applied-in-6-8-dabs/717365>\
**Category:** Factual Questions\
**Created:** [April 10, 2015, 8:09pm UTC](https://boards.straightdope.com/t/how-does-topical-non-systemic-anti-tic-flea-dog-goop-cover-the-whole-coat-if-applied-in-6-8-dabs/717365 "2015-04-10T20:09:53Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\
**Post date:** [April 10, 2015, 8:09pm UTC](https://boards.straightdope.com/t/how-does-topical-non-systemic-anti-tic-flea-dog-goop-cover-the-whole-coat-if-applied-in-6-8-dabs/717365/1 "2015-04-10T20:09:53Z")

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See subject.

Shelled out $100 bucks for new formulation that wouldn’t get my dog all itchy and distressed-panting, which required giving him some Benadryl and getting him all sleepy, to cure what I thought was some sort of allergic reaction.

You squeeze a small tube of goop in 6-8 dabs on the skin, burrowing down through the coat as much as possible. I always figured it was absorbed somehow and did it’s stuff, and also that that was what was causing the allergic reaction.

Vet tells me it’s not a systemic med, and it’s “the hair follicles reacting as the medicine moves through the skin cells and spreads throughout the coat, and the dog is just miserable about that,” not a histamine-thing.

“Skin cells shuttling around the med” sounds very :dubious:.

But what’s going on that the topical med apparently works? Leaving aside why it effects my dog’so comfort.

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**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\
**Post date:** [April 10, 2015, 8:15pm UTC](https://boards.straightdope.com/t/how-does-topical-non-systemic-anti-tic-flea-dog-goop-cover-the-whole-coat-if-applied-in-6-8-dabs/717365/2 "2015-04-10T20:15:10Z")

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I found the following. Seems to answer the question:

> [@](#):
>
> Some products are placed on the skin and act on the skin without being absorbed. These range from sprays to many of the ‘spot products’ to collars. The advantage is that these products will repel fleas and kill them before they bite, so they are good for flea allergies. The major disadvantage is that they wash off. Also, it is very important to remember that if a surface acting product is used ‘locally’ (as in a spot product or collar as opposed to spraying the entire dog), there is a ‘concentration gradient’ similar to putting cream in coffee without stirring. The product will be much more concentrated where applied, and less so the further away from the application area. (The ‘lipid-layer’ products like Advantage concentrate in the deeper layers of the skin. They are not actually ‘systemic’ in that they don’t get into the bloodstream - a consideration for clients concerned about ‘giving all those poisons’ to their dog. However, as they are not on the surface, don’t wash off nor give the repellant effect of a surface product, for simplicity we will discuss them as a ‘systemic.’)
> 
> SOURCE: [IDN Poker, Agen Poker Online, Daftar IDN Poker, IDNPLAY APK](http://www.mercyanimalhospitalri.com/fleasandticks.php)

TL;DR: The medicine spreads out from the area of treatment a ways. If you put in 6-8 strategic locations coverage should be pretty good.