Thank you Denise for taking the time to reach out to us regarding our products. We understand your concerns regarding the health of your rotties. When it comes to our insect products, we have developed them to be able to be used as often as needed depending on how intense the insect population is. Typically with the wipe-on oil version you only need to apply every 1-2 days right before your animal is exposed to insects.
The scent of the oil helps to confuse the insects and makes them want to leave your pet alone and feed on something else. You can also combine this product with our insect repellent spray so that you don't have to use as much oil.
I hope this helps, but if you have any further questions please feel free to reach out to us.