Thank you for the additional information.

Sorry to hear that she is so itchy at this time. Based on what you are describing, the Trifexis should be killing the adult fleas that could be near her, but unfortunately if she did get a flea on her she could have been bit before the flea died. One flea bite can cause dogs to be very itchy if they are allergic to flea bites. The main reason I am concerned that she may have been bit by a flea is that the flat worms that you are seeing are called tapeworms. These worms come mainly from fleas on dogs. She may have been biting or licking at her fur and ingested an actual flea. The tapeworms then came from the flea that she ingested.

The tapeworms are very easy to get rid of but the most important part is controlling the fleas so that she does not get more tapeworms. You can purchase a medication from your vet called Droncit or drug name praziquantel. One dose will help remove all of the tapeworms from her. You can actually buy this medication online also. More then likely your cat may have carried the fleas into house which got on to Bella. If you are not already treating your cat with a flea preventive I would recommend treating your cat. Be careful with many of the over the counter flea preventives for cats though. I would recommend using either Advantage or even safer would be Frontline Plus for cats. These are much better products then the other flea preventives in cats.

For Bella's itching you can give her some Benadryl. This may help reduce some of the itchiness. The dose is about 1 mg per pound every 12 hours by mouth. If this is not helping you may have to ask your vet about a stronger medication such as prednisone or a different anti histamine.

Overall I would definitely make sure all of the animals are protected against the fleas otherwise this may be an ongoing problem for Bella.

Hope this helps -please feel free to reply if you have any questions.