How can one get rid of a recurring whisper in the soul that Satan is an animal when remembering Allah or supplicating?

We ask Allah to grant you well-being from the whispers (waswas) you are suffering from. We advise you to strive against yourself to get rid of them, because they are a serious illness. The best treatment for them is complete avoidance and not going along with them, and asking Allah for well-being and seeking refuge in Him from their evil, along with frequent remembrance (dhikr) and supplication (du'a), and occupying your time with learning and serving yourself and your family, and avoiding isolation.