Is my dog's Seresto collar safe? What are its chemicals used for?

It is certainly not too much to use a Seresto collar with Sentinel! In my experience, Sentinel alone is not sufficient for proper flea control, but is great for heartworm and intestinal parasite prevention. The Seresto collar will prevent ticks and fleas, which is quite important. To answer your question, yes, use both! :-)

It is ok to use Seresto along with other topical products, just not oral ones. In some pets there can be a little skin irritation, so watch out for that and notify your vet if this happens. Otherwise, you should be fine to go ahead with Seresto to see if this does the trick. I would also recommend using a flea fogger to treat your home, which can be found at your local Home Depot or Lowe's. If you still don't have good results with the Seresto collar, then I would wait at least 2 weeks and consider better products such as Simparica or Nexgard. Best of luck with your flea issue and Nova moving forward. Take care!

Yes you can combine them as they are completely different types of medication. Seresto contains Flumethrin (tick repellent) and Imidacloprid (interferes with the development of fleas and their larvae). Revolution is an avermectin which kills internal parasites such as heartworm and intestinal worms and actually kills fleas.

Yes, Seresto is a good choice. From personal experience I find that swimming reduces the number of months this product works, so best to remove before getting wet, otherwise this is a great product for where you live. Please keep in mind that this does not protect against heartworm.

You can try a seresto collar after the 2 week application of an advantix. It is not for everyone as each bath starts the transcription process again so it decreases the 8 month time frame it is labeled to last. If you are worried above side effects, which can occur with any product, you may want to talk to your vet about monthly tablets or once every 3 month tablets that are for fleas and ticks now.

The Seresto flea/tick collar is the only one on the market that is safe and effective - the others, including Adams, are often dangerously toxic for the dog and not effective at all for fleas in my experience. Advantix is definitely a better choice than PetArmor, but the most effective option available for fleas and ticks currently would be an oral medication like Nexgard or Bravecto. I would recommend getting a prescription from your veterinarian for one of these medications, if possible - this will eliminate the need for any topical medication or flea collars, and will also work much better.

Yes a Seresto collar and Nexgard can be used together, however both Nexgard and Seresto are highly effective against fleas and ticks and therefore it is not necessary to double up. You can just as effectively use either on its own.